Nutrition

Test 1

Chapter 1 — The Science of Nutrition: Factors That Influence Health

1. What Is Nutrition?

Nutrition

• Science of food

• Studies:

  • Nutrient actions

  • Nutrient interactions

  • Nutrient balance

  • Relationship between nutrients, health, and disease

• Includes:
  Ingestion → Digestion → Absorption → Transport → Utilization → Excretion

• Food provides nutrients needed to:

  • Fuel cells

  • Build cells

  • Maintain cells

Why nutrition matters

Many leading causes of death in the U.S. are influenced by:

• Poor diet

• Excessive energy intake

• Inadequate physical activity

2. Nutrients

Nutrient

A chemical substance found in food that the body uses to:

• Grow

• Survive

• Reproduce

• Provide energy

• Maintain life

Essential nutrient

A nutrient that:

1. Has a specific biological function

2. The body cannot make or cannot make enough of

3. Not getting enough causes a decline in normal function

4. Adding it back can restore normal function before permanent damage occurs

6 Classes of Essential Nutrients

1. Carbohydrates

2. Proteins

3. Lipids (fats)

4. Water

5. Vitamins

6. Minerals

Macronutrients vs. Micronutrients

3. Carbohydrates

Main facts

• Made of carbon, hydrogen, and oxygen

• Main sources:

  • Fruits

  • Vegetables

  • Grains

  • Beans

• Provide 4 kcal/g

• Major energy source for most cells

Types

Simple carbohydrates

• Table sugar (sucrose)

• Blood glucose

Complex carbohydrates

• Starch

• Glycogen

• Fiber

Important terms

• Monosaccharides = single sugars

• Disaccharides = two sugars

• Polysaccharides = many sugars

4. Lipids

Main facts

• Made mostly of carbon, hydrogen, and oxygen

• Insoluble in water

• Provide 9 kcal/g

• More energy-dense than carbohydrates and protein

Fat vs. Oil

• Fat: mostly saturated fatty acids → usually solid at room temperature

• Oil: mostly unsaturated fatty acids → usually liquid at room temperature

Triglycerides

The major form of fat in food and the body.

Functions:

• Major energy source

• Major form of stored energy

Structure:

• 3 fatty acids + 1 glycerol backbone

Saturated fats

• Usually solid at room temperature

• Mostly from animal sources

• Can raise blood cholesterol

• Associated with cardiovascular disease

Unsaturated fats

• Usually liquid at room temperature

• Mostly from plant sources

• Generally considered healthier than saturated fats

Remember:

Carbs = 4 kcal/g
Protein = 4 kcal/g
Fat = 9 kcal/g

5. Protein

Main facts

• Made of carbon, oxygen, hydrogen, and nitrogen

• Made of chains of amino acids

• Provides 4 kcal/g

Functions

Proteins are important structural/functional components of:

• Bone

• Muscle

• Blood

• Cell membranes

• Enzymes

• Immune factors

Amino acids

• 20 amino acids are found in food

• 9 are essential

6. Vitamins

What do vitamins do?

• Help chemical reactions occur

• Some help release energy from carbohydrates, fats, and proteins

• Vitamins do NOT directly provide energy

13 vitamins → 2 groups

Fat-soluble vitamins

A, D, E, K

• Dissolve in fat

• More likely to accumulate in the body

• Greater potential for toxicity

Memory trick: ADEK

Water-soluble vitamins

Vitamin C + B vitamins

• Dissolve in water

• More readily excreted from the body

• More likely to be destroyed by cooking

Example

Vitamin C → helps with collagen synthesis

7. Minerals

Main facts

• Inorganic substances

• Do not contain carbon atoms bound to hydrogen

• Not destroyed by cooking

• Provide no energy

• Needed for normal body functions

Important roles:

• Nervous system

• Skeletal system

• Water balance

Two groups

Major minerals

• Needed in gram amounts

• Examples:

  • Sodium (Na)

  • Potassium (K)

  • Chloride (Cl)

  • Calcium (Ca)

  • Phosphorus (P)

Trace minerals

• Needed in amounts less than 100 mg/day

• Examples:

  • Iron (Fe)

  • Zinc (Zn)

  • Copper (Cu)

  • Selenium (Se)

8. Water

Important facts

• Nutrient needed in the largest quantity

Functions

• Solvent

• Lubricant

• Transports nutrients to cells

• Regulates body temperature

Sources

• Food

• Drinks

• Byproduct of metabolism

9. Phytochemicals & Zoochemicals

These are physiologically active compounds that provide health benefits but are not essential nutrients.

Phytochemicals

Come from plants:

• Fruits

• Vegetables

• Whole grains

• Legumes

Example:

• Glucosinolates in broccoli may help protect against cancer.

Zoochemicals

Come from animals.

Example:

• Lutein and zeaxanthin in eggs may slow macular degeneration.

Important

Multivitamins/mineral supplements contain few or none of these compounds.

Idea: It's better to get nutrients and beneficial compounds from whole foods when possible.

10. Energy

What does the body use energy for?

Energy allows the body to do work, including:

1. Build new compounds

2. Perform muscular movements

3. Promote nerve transmissions

4. Maintain ion balance:

   • Within cells

   • Between cells

   • In blood

Energy is NOT a nutrient

Energy itself is not a nutrient.

11. Calories & Kilocalories

Calorie (cal)

Amount of heat needed to raise the temperature of 1 gram of water by 1°C.

Kilocalorie (kcal)

Amount of heat needed to raise the temperature of 1,000 grams of water by 1°C.

• 1 kcal = 1,000 cal

• Food labels use kilocalories, although they usually just say "Calories."

Energy from macronutrients

12. North American Diet

Acceptable Macronutrient Distribution Ranges (AMDR)

Example from the slide:

• 50% carbohydrates

• 33% fat

• 16% protein

Problems with the North American diet

Common characteristics include:

• Too many calories

• Too much protein from animal sources (60%)

• Too many carbohydrates from simple sugars (50%)

• Too much fat from animal sources/saturated fat

General recommendations

Increase:

• Vitamin A

• Vitamin E

• Potassium

• Iron

• Calcium

• Fruits

• Vegetables

• Whole grains

• Reduced-fat dairy

Decrease/moderate:

• Sodium

• Sugary soft drinks

• Fatty foods

13. What Influences Food Choices?

We eat to satisfy:

• Hunger

• Social needs

• Psychological needs

Hunger

• Physiological/internal need for food

Appetite

• Psychological/external desire to eat

Food choices can be influenced by many factors, including social and psychological factors.

14. Nutritional Health Status

Desirable nutritional status

• Optimal health status

• Nutrients are available in amounts needed for normal body function

Malnutrition

Includes both:

• Undernutrition

• Overnutrition

Undernutrition

• Nutrient intake does not meet the body's needs

• Nutrient stores become depleted

Subclinical deficiency

• Early stage of nutrient deficiency

• Symptoms may not be detectable yet

Overnutrition

• Consuming more nutrients than the body needs

• Most common form in industrialized countries = excess energy intake

• Can lead to obesity

15. Assessing Nutritional Status

Nutrition assessment helps determine nutritional fitness.

6 areas of assessment

1. Anthropometric
Measures body size/composition:

• Height

• Weight

• Skinfold thickness

• Arm muscle circumference

• Body composition

2. Biochemical
Looks at:

• Bloodwork

• Urine

3. Clinical
Physical examination:

• Skin

• Eyes

• Tongue

• Ability to walk

4. Dietary
Looks at:

• Usual food intake

• Food allergies

• Supplements

5. Environmental
Looks at:

• Education

• Economic background

• Marital status

• Number of people in household

• Housing conditions

6. Medical/Familial history
Includes:

• Current/past diseases

• Surgeries

• Weight history

• Medications

• Family medical history

Limitations

Signs/symptoms aren't always specific.

For example:

• Diarrhea

• Skin conditions

• Fatigue

These could have causes unrelated to nutrition.

Also, deficiencies can take years to show their effects.

Example:

• Calcium deficiency during teen years may contribute to osteoporosis later in life.

16. Scientific Research & Nutrition

Why use the scientific method?

The scientific method is a systematic and objective approach used to:

• Discover facts

• Generate knowledge

• Reduce/eliminate errors

Why it matters in nutrition

It helps:

• Create evidence-based dietary guidelines

• Identify relationships between diet and disease

• Replicate and verify findings

• Develop scientific theories/laws

17. Hypothesis

A hypothesis is a proposed explanation that can be tested through research.

James Lind & Scurvy

• Sailors on long voyages often developed scurvy

• James Lind noticed sailors ate fewer fruits and vegetables

• He hypothesized that something missing from their diet caused scurvy

• He tested different substances, including citrus juice

• Citrus prevented/cured scurvy

• We now know vitamin C prevents scurvy

18. Experimental Designs

In vitro

Means "in glass."

• Experiments performed outside a living organism

• Often use cells or parts of living organisms

• Example: test-tube experiments

In vivo

Means "in life."

• Experiments performed on whole living organisms

• Examples:

  • Rats

  • Humans

19. Animal Research

Laboratory animals may be used when a hypothesis cannot ethically or practically be tested on humans.

Before animal studies:

• Researchers need approval from the Institutional Animal Care and Use Committee (IACUC)

Why use animal models?

• Animals can develop conditions that mimic human diseases

• Helps researchers understand:

  • Causes

  • Diagnosis

  • Safety/effects of treatments

20. Human Experimental Research

Human studies investigate health outcomes from dietary practices.

Before a human study:

• Researchers need approval from an Institutional Review Board (IRB).

Gold standard

Randomized controlled trial (RCT)

The slides describe an ideal design as:

• Randomized

• Double-blinded

• Cross-over

• Placebo-controlled

Double-blind

• Neither participants nor researchers know who is in each group.

Cross-over

• Participants receive both treatments being compared, such as treatment and placebo.

Placebo

• A fake treatment that resembles the real treatment.

• Example: sham pill.

21. Epidemiological Studies

Study:

• Occurrence

• Distribution

• Causes of health problems in populations

Case-control study

Compares:

• People with a health condition

• Similar people without the condition

Example:

• People with lung cancer vs. people without lung cancer

Cohort study

• Measures variables in a group of people over time

22. Types of Cohort Studies

Prospective

Think: FORWARD

• Starts with healthy people

• Follows them into the future

• Looks for factors that may contribute to changes in health

Retrospective

Think: BACKWARD

• Looks at people's past exposures

• Used to understand why some people developed a condition and others didn't

Memory trick:
Prospective = forward
Retrospective = backward

23. Correlation

Epidemiological studies can establish correlation.

Correlation

Two variables change during the same period.

Positive/direct correlation

Both variables move in the same direction.

Example:

• As X increases → Y increases

Negative/inverse correlation

Variables move in opposite directions.

Example:

• As X increases → Y decreases

🚨 VERY IMPORTANT:

Correlation does NOT imply causation.

Epidemiological studies cannot establish cause-and-effect relationships by themselves.

Two things may change together because of:

• Coincidence

• Another factor

• A third variable

Spurious correlation

A relationship that appears to exist between two variables but does not represent a true cause-and-effect relationship.

24. Follow-Up Studies

One experiment is NOT enough to accept a hypothesis.

Researchers need:

• More experiments

• Replication

• Consistent results

The more evidence supporting a hypothesis, the more likely it is to be true.

This creates cumulative evidence.

25. Scientific Journals

Scientific journal

A publication containing original scientific articles that are:

• Written by scientists

• Peer-reviewed

• Evaluated by experts in the same field

Why scientific journals matter

They:

• Provide real data

• Use expert peer review

• Improve quality and credibility

• Help inform dietary guidelines

• Help combat misinformation

Examples:

• JAMA

• Nutrition Reviews

• Journal of the Academy of Nutrition and Dietetics

• The BMJ

• British Journal of Nutrition

26. Evaluating Nutrition Claims

When you see a nutrition claim, ask:

🚩 Warning signs

Be cautious if the claim:

• Only discusses advantages

• Claims a new/"secret" breakthrough

• Claims to cure a disease

• Sounds too good to be true

• Is extremely biased against the medical community

• Uses dramatic testimonials

Ask about the research:

• What are the person's scientific credentials?

• How much research exists?

• How large was the study?

• How long did it last?

• What type of study was conducted?

27. Reliable Nutrition Information

Good sources include:

• Scientific books

• Government organizations

• Professional organizations

• Educational organizations

• Consumer organizations

• Scientific journals

• Qualified consultants

Websites

Generally:

• .gov → government

• .edu → educational institutions

• .org → organizations

Be more cautious with:

• .com websites

A website ending doesn't automatically make information true, but it can help you identify the type of source.

28. Dietary Supplements

Examples:

• Vitamins

• Minerals

• Amino acids

• Herbal remedies

Under the Dietary Supplement Health and Education Act (DSHEA) of 1994, these products are classified as foods, not drugs.

Important

Supplements are:

• Less regulated than medications

• Not all thoroughly evaluated by scientists

According to the slides:

• The FDA must generally establish that a product is unsafe to remove it from the market rather than manufacturers having to prove safety before distribution.

29. Being a Savvy Consumer

When buying nutrition-related products:

1. Read and scrutinize labels

2. Look for scientific evidence

3. Don't use products for purposes not listed on the label

4. Be skeptical of exaggerated health claims

5. Look for FDA disclaimers on certain health claims

NUTR 2360 — Chapter 2: Tools of a Healthy Diet

1. Planning a Healthy Diet

To plan a healthy diet and reduce disease risk, use:

• Dietary Reference Intakes (DRIs)

• Dietary Guidelines for Americans

• Food labels

• Nutrient databases

• Knowledge of nutrient density and energy density

• Healthy eating principles:

  • Variety

  • Balance

  • Moderation

  • Nutrient density

  • Energy density

2. Dietary Reference Intakes (DRIs)

What are DRIs?

DRIs = recommendations for how much of a nutrient people need for optimal health.

• Set for almost 40 nutrients

• Developed by the Food and Nutrition Board

• Apply to the U.S. and Canada

• Differ based on:

  • Age

  • Gender (after age 9)

  • Pregnancy

• Should be considered using average intake over several days, not just one day.

⭐ 5 DRI standards

1. EAR = Estimated Average Requirement

2. RDA = Recommended Dietary Allowance

3. AI = Adequate Intake

4. UL = Tolerable Upper Intake Level

5. EER = Estimated Energy Requirement

⚠ Also know:

AMDR = Acceptable Macronutrient Distribution Range

It is related to DRIs but is NOT technically a DRI.

3. EAR — Estimated Average Requirement

Definition:

The daily nutrient intake estimated to meet the needs of 50% of healthy people in a specific life-stage group.

• Set for 17 nutrients

• Used mainly for evaluating groups, NOT individuals.

• Requires an accurate way to measure whether the body is functioning properly.

• These measurements are called functional markers.

Example:

If 100 people need a certain amount of Vitamin X:

• EAR meets the needs of about 50 people

• The other 50 may need more.

⭐ Remember:

EAR = 50%

4. RDA — Recommended Dietary Allowance

Definition:

The daily nutrient intake sufficient to meet the needs of 97–98% of healthy individuals.

• Based on the EAR

• Can only be established when an EAR exists

• Generally:

RDA ≈ EAR × 1.2

Important:

RDA is higher than the average person's actual requirement.

If someone regularly consumes less than the RDA, it does not automatically mean they are deficient.

However, regularly consuming below the EAR increases the concern for deficiency.

⭐ Remember:

RDA = 97–98%

5. AI — Adequate Intake

Definition:

A recommended intake used when there is not enough research to establish an EAR/RDA.

Based on observed or experimentally supported estimates of intake needed to maintain good health.

Examples of what researchers may look at:

• Bone health

• Normal body function

Important:

• Intended to cover the needs of about 97–98% of people

• Can be used for individuals

• Used when an EAR cannot be determined

⭐ Remember:

AI = used when there isn't enough evidence to establish an EAR.

6. UL — Tolerable Upper Intake Level

Definition:

The highest daily nutrient intake that is unlikely to cause harmful effects in 97–98% of healthy people.

• Applies to chronic/regular daily intake

• Protects against toxicity

• It is a ceiling, NOT a goal.

⭐ Remember:

UL = don't regularly go above it.

7. EER — Estimated Energy Requirement

Definition:

The average amount of energy/calories needed each day for a specific life-stage group.

EER depends on:

• Age

• Gender

• Height

• Weight

• Physical activity/energy expenditure

Purpose:

Helps promote and maintain a healthy body weight.

Important:

Excess energy can be stored as body fat.

8. DRI Quick Comparison ⭐

Easy memory trick:

EAR → 50%
RDA → 97–98%
UL → Upper limit
EER → Energy

9. How to Use DRIs

DRIs are useful for:

• Planning diets

• Making sure nutrient needs are met

• Evaluating nutrient intake

• Avoiding excessive intake

For diet planning:

✅ Try to meet the RDA or AI
✅ Stay below the UL
❌ Don't intentionally aim for the UL

Important limitation:

DRIs are designed for healthy people.

They are not appropriate for people who are undernourished or have certain diseases/health conditions without appropriate professional guidance.

10. AMDR — Acceptable Macronutrient Distribution Range

AMDR is NOT a DRI.

It gives recommended percentages of calories from:

• Carbohydrates

• Protein

• Fat

Purpose:

Help reduce the risk of nutrition-related chronic diseases.

11. Nutrient Density ⭐

Definition:

Nutrient density = how much nutrition a food provides compared with how much energy (calories) it provides.

A food is nutrient dense when it provides a large amount of nutrients for relatively few calories.

Example:

An orange provides a lot of vitamin C for relatively few calories → nutrient dense.

Calculating Nutrient Density

Step 1:

Calculate the percentage of the nutrient's RDA:

Nutrient in serving ÷ RDA × 100

Step 2:

Calculate the percentage of daily calories:

Calories in serving ÷ EER × 100

Step 3:

Compare the two percentages.

If the % of nutrient needs is greater than the % of calorie needs, the food is nutrient dense.

Example: Orange

• 70 mg vitamin C

• RDA = 65 mg

• 65 calories

• EER = 1,800 calories

Vitamin C:

70 ÷ 65 × 100 = 108%

Calories:

65 ÷ 1,800 × 100 ≈ 4%

So the orange provides about:

• 108% of vitamin C needs

• 4% of calorie needs

➡ Very nutrient dense

12. Energy-Dense / Empty-Calorie Foods

These foods provide lots of calories but relatively few nutrients.

Usually high in:

• Sugar

• Fat

Examples:

• Sugared soft drinks

• Chips

• Cookies

• Candy

⭐ Difference:

Nutrient dense → lots of nutrients, relatively few calories

Energy dense → lots of calories, relatively few nutrients

13. Daily Values (DVs)

What are DVs?

Daily Values are general standards developed by the FDA for food labels.

They are found on the Nutrition Facts label.

DVs vs DRIs

DRIs:

• More specific

• Depend on age, gender, pregnancy, etc.

DVs:

• General standards

• Designed to be practical for food labels

• Usually apply to people over age 4

⭐ Important:

The Daily Values on most food labels are for people over 4 years old.

Exceptions:

• Infants

• Toddlers

• Pregnant/lactating women

when the product is specifically marketed for those groups.

14. RDI — Reference Daily Intake

RDI = standards used for vitamins and most minerals on food labels.

For people over age 4, the RDI generally uses the highest value needed among different life-stage groups.

Example:

If adolescent females and adult women have the highest iron requirement of 18 mg/day, the RDI for iron may be based on that value.

15. DRV — Daily Reference Value

DRVs are standards used for:

Energy-producing nutrients:

• Fat

• Saturated fat

• Carbohydrates

• Protein

• Fiber

Also:

• Cholesterol

• Sodium

Important:

For energy-producing nutrients, the FDA uses 2,000 calories/day as the reference amount for calculating %DV.

⭐ Remember:

RDI → vitamins + most minerals

DRV → fat, carbs, protein, fiber, etc.

16. Nutrition Facts Labels

Food labels provide information about:

• Product name

• Manufacturer

• Amount of food in package

• Ingredients

• Allergens

• Nutrition Facts

Ingredients list:

Ingredients are listed in descending order by weight.

➡ The ingredient present in the greatest amount is listed first.

17. Nutrition Facts Panel

The Nutrition Facts panel gives nutrient information based on a serving size.

Serving sizes are:

• Specified by the FDA

• Based on typical amounts Americans eat

Nutrients commonly required on labels:

• Calories

• Total fat

• Saturated fat

• Trans fat

• Cholesterol

• Sodium

• Total carbohydrates

• Fiber

• Total sugars

• Added sugars

• Protein

• Vitamin D

• Calcium

• Iron

• Potassium

⚠ Protein:

For foods intended for people over age 4, listing the %DV for protein is not mandatory because protein deficiency is not considered a major public health concern in the U.S.

18. Nutrients Americans Often Get Too Much/Little Of

Many people get TOO MUCH:

• Fat

• Saturated fat

• Trans fat

• Cholesterol

• Sodium

• Sugar

Many people DON'T GET ENOUGH:

• Fiber

• Calcium

• Iron

• Potassium

• Vitamin D

⭐ This explains why many of these nutrients appear prominently on Nutrition Facts labels.

19. Claims on Food Labels

Food package claims must follow FDA regulations.

There are 3 major types:

1. Nutrient content claims

2. Health claims

3. Structure/function claims

Nutrient Content Claims

Describe the amount or level of a nutrient in a food.

Examples include claims such as:

• Low fat

• High calcium

• Good source of fiber

➡ FDA regulates/approves these claims.

Health Claims

Describe a relationship between:

A food/nutrient ↔ a disease or health condition

Health claims must meet FDA requirements.

They must have significant scientific agreement supporting them.

⭐ Remember:

Health claim = food/nutrient + disease relationship

Structure/Function Claims

Describe how a nutrient affects the:

• Structure of the body

• Function of the body

Important:

The FDA does not approve or authorize these claims in the same way it approves health claims.

The manufacturer is responsible for making sure the claim is accurate and not misleading.

⭐ Easy difference:

Health claim → disease

Structure/function → body function/structure

20. Nutrient Databases

Nutrient databases allow us to:

• Estimate calories in foods

• Estimate nutrient amounts

• Compare intake with dietary recommendations

Limitations:

They cannot fully account for:

• Factors that change nutrient levels in foods

• How nutrients are absorbed and used by the body

➡ Database values are estimates, not always exact amounts.

21. Dietary Guidelines for Americans (DGA)

The Dietary Guidelines for Americans are the U.S. government's foundation for:

• Nutrition policy

• Nutrition education

• Healthy eating recommendations

Developed by:

• USDA

• DHHS (Department of Health and Human Services)

They are based on current scientific evidence about:

• Nutrition

• Physical activity

• Healthy lifestyle choices

22. Goals of the Dietary Guidelines

The guidelines aim to meet nutrient needs while reducing risk of:

• Obesity

• Hypertension

• Cardiovascular disease

• Type 2 diabetes

• Osteoporosis

• Alcohol-related problems

• Foodborne illness

⭐ Main idea:

Nutrient needs should be met primarily through food.

23. 2025–2030 Dietary Guidelines

Your slides say the 2025–2030 Dietary Guidelines emphasize:

• Eat the right amount for you

• Prioritize protein foods at meals

• Consume dairy

• Eat vegetables and fruits throughout the day

• Include healthy fats

• Focus on whole grains

• Limit highly processed foods

• Limit added sugars

• Limit refined carbohydrates

• Limit alcoholic beverages

⭐ Main theme:

Choose nutrient-dense foods and limit foods that provide lots of calories with fewer beneficial nutrients.

24. MyPlate / Food Pyramid

Historical progression:

1947 → 7 food groups

⬇

1992 → Food Guide Pyramid

⬇

2005 → MyPyramid

⬇

2011–2025 → MyPlate

⬇

2025–2030 → New Food Pyramid

MyPlate:

Previously emphasized 5 food groups:

• Fruits

• Vegetables

• Grains

• Protein

• Dairy

Its purpose was to help people visualize what a healthy plate could look like.

Important for your class: Your slides specifically state that MyPlate was discontinued as of 2026 and the 2025–2030 guidelines use a Food Pyramid instead.

25. Concerns About the New Guidelines

The Academy of Nutrition and Dietetics supports:

• Nutrient-dense foods

• Fruits and vegetables

• Whole grains

• Limiting highly processed foods

• Limiting added sugars

• Keeping saturated fat below 10% of total calories

• Prioritizing healthier fats

• More attention to fiber and microbiome health

Concerns raised by the Academy:

• Emphasis on butter, beef tallow, red meat, and full-fat dairy

• Lack of consideration for people who don't consume dairy

• Recommendations concerning low-calorie non-nutritive sweeteners

• Synthetic food dyes and the need for more research

⭐ For your test:

Know that these are concerns expressed by the Academy, not necessarily facts that the entire nutrition field agrees upon.

26. Putting Dietary Guidelines Into Action

A healthy eating plan should:

1. Consider your current health

Think about:

• Current health

• Family history

2. Identify changes

Figure out what parts of your diet need improvement.

3. Make a plan

Choose realistic changes you can incorporate.

4. Evaluate

See whether the changes are actually helping.

NUTR 2360 — Chapter 4: Human Digestion and Absorption

1. Organization of the Human Body

The body is organized from smallest to largest:

Cells → Tissues → Organs → Organ Systems

Cells

The cell is the smallest functional unit of the body.

Cells can:

• Grow

• Absorb nutrients

• Use energy

• Perform metabolic/physiological functions

• Remove waste

Cells need:

• Energy → carbohydrates, proteins, lipids → converted into ATP

• Water

• Building materials → such as amino acids

• Chemical regulators → such as vitamins

⭐ ATP

ATP (adenosine triphosphate) = usable energy for cells.

2. Four Types of Human Tissue

⭐ Remember:

Tissues combine to form organs.

3. Digestive Organ System

The digestive system:

• Digests food

• Absorbs nutrients

• Removes waste

• Makes nutrients available for cells

• Helps regulate the body

• Helps with immune function

• Houses beneficial bacteria called microbiota

Major organs of the GI tract:

1. Mouth

2. Esophagus

3. Stomach

4. Small intestine

5. Large intestine

6. Anus

Accessory organs:

• Liver

• Gallbladder

• Pancreas

⭐ Important:

Accessory organs help digestion but food does NOT pass through them.

4. Sphincters

Sphincters = ring-like muscles that open and close to control movement through the GI tract.

They prevent contents from moving the wrong direction.

⭐ Know where the major sphincters are located.

Important ones include:

• Lower esophageal sphincter (LES) → between esophagus and stomach

• Pyloric sphincter → between stomach and small intestine

• Sphincter of Oddi → controls bile/pancreatic secretions entering the duodenum

5. GI Motility

GI motility = coordinated contraction and relaxation that moves and mixes food through the digestive tract.

Peristalsis

• Wave-like contractions

• Pushes food forward

• Helps move food through the GI tract

Think:

Peristalsis = propulsion

Segmentation

• Back-and-forth contractions

• Breaks up and mixes food

• Occurs mainly in the small intestine

• Helps nutrients contact the intestinal wall

Think:

Segmentation = mixing

Mass Movements

• Large areas of the intestine contract at once

• Occur in the large intestine

• Move feces toward the rectum

Normal transit time:

A meal typically takes about 24–60 hours to travel through the GI tract.

6. Digestive Enzymes

Digestive enzymes = proteins that speed up digestion.

They break large food molecules into smaller molecules that can be absorbed.

They work through:

Hydrolysis

Hydrolysis uses water to break chemical bonds.

Enzymes act on:

• Carbohydrates

• Proteins

• Fats

Produced by:

• Salivary glands

• Stomach

• Pancreas

• Small intestine

⭐ Most digestive enzymes are produced by the pancreas.

7. What Happens if You Don't Produce Enough Enzymes?

Insufficient enzyme production can cause:

Incomplete digestion → undigested food reaches large intestine → bacteria break it down → gases/acids → bloating and abdominal distention

It can also cause limited nutrient absorption.

This can happen when the:

• Small intestine is diseased

• Pancreas is diseased

• Person is malnourished

👄 8. Digestion Begins in the Mouth

Teeth

• Tear and grind food

• Chewing increases surface area

• More surface area = enzymes can work more effectively

Saliva

Food mixes with saliva and forms a bolus.

Bolus = chewed food mixed with saliva.

9. Saliva

Salivary glands produce about 1 liter (4 cups) of saliva per day.

Important components:

Lysozyme

• Helps destroy bacteria

Mucus

• Lubricates food

• Holds the bolus together

Amylase

• Begins digestion of starch

• Breaks starch into smaller sugars

Lipase

• Begins fat digestion

⭐ Remember:

Amylase → carbohydrates/starch

Lipase → fat

10. Esophagus

The esophagus is a muscular tube connecting the:

Pharynx → stomach

Swallowing

Moves the bolus from the mouth into the esophagus.

Epiglottis

A flap that helps prevent food from entering the:

Trachea (windpipe)

Instead, food is directed toward the esophagus.

🥣 11. Stomach

The stomach acts like a mixing tank.

Food enters through the:

Lower esophageal sphincter (LES)

LES problem:

If the LES doesn't work properly → stomach contents can move upward → heartburn/reflux

Stomach functions:

• Stores food

• Mixes food with gastric secretions

• Begins significant protein digestion

• Produces substances needed for digestion

Limited absorption occurs here:

The stomach can absorb:

• Water

• Some fat

• About 20% of alcohol

12. Gastric Juice

The stomach produces about 8 cups of gastric juice per day.

Gastric juice contains:

Hydrochloric acid (HCl)

• Helps destroy bacteria and viruses

• Helps dissolve minerals

• Denatures/inactivates proteins

• Activates pepsinogen into pepsin

Intrinsic factor

• Produced by parietal cells

• Important for vitamin B12 absorption later in the small intestine

Pepsinogen

• Inactive protein-digesting enzyme

• Produced by chief cells

• Activated into pepsin

Gastric lipase

• Helps digest fat

13. Protein Digestion in the Stomach ⭐

Know this sequence:

Gastrin → HCl + pepsinogen released

⬇

HCl converts pepsinogen → pepsin

⬇

Pepsin breaks proteins → peptides

⭐ Pepsin = protein digestion

14. Gastrin

Gastrin = hormone produced in the stomach.

It:

• Stimulates release of HCl

• Stimulates release of pepsinogen

• Stimulates stomach motility

Gastrin levels are highest at the beginning of a meal and decrease as the meal continues.

15. Ghrelin

Ghrelin = hormone that increases appetite and food intake.

⭐ Remember:

Ghrelin → hunger/appetite increases

16. Stomach Protection

The stomach produces mucus.

Mucus:

• Lubricates the stomach

• Protects the stomach lining from HCl and pepsin

Prostaglandins

Help support mucus production.

NSAIDs

Examples include aspirin and other nonsteroidal anti-inflammatory drugs.

They can reduce prostaglandin production.

⬇

Less mucus protection

⬇

Stomach lining becomes more vulnerable to acid damage.

17. Chyme

When food enters the stomach, it mixes with stomach secretions.

Bolus → stomach → mixed with gastric secretions → chyme

Chyme:

Partially digested, acidic food mixture.

It leaves the stomach through the:

Pyloric sphincter → small intestine

Timing:

It generally takes about 1–4 hours for stomach contents to move into the small intestine.

18. Small Intestine ⭐⭐⭐

The small intestine is the major site of digestion and absorption.

About 95% of food energy is digested/absorbed here.

Three sections:

1. Duodenum

2. Jejunum

3. Ileum

Easy memory trick:

DJI

Duodenum
Jejunum
Ileum

19. What Does the Small Intestine Absorb?

The small intestine absorbs:

• Glucose

• Amino acids

• Fat

• Vitamins

• Minerals

• Water

• Alcohol

⭐ Major takeaway:

Most nutrient absorption happens in the small intestine.

20. Villi and Microvilli ⭐

The small intestine has structures that greatly increase surface area.

Villi

Finger-like projections lining the small intestine.

Microvilli

Tiny projections on the surface of intestinal cells.

Together they create a huge surface area for absorption.

Enterocytes

Enterocytes = intestinal cells that absorb nutrients.

They have a brush border containing microvilli.

The brush border also contains enzymes.

Why is surface area important?

More surface area → more contact with nutrients → more efficient absorption

21. Segmentation Helps Absorption

Segmentation:

• Mixes chyme

• Moves chyme back and forth

• Slows its movement

• Brings nutrients into contact with the villi

➡ This helps absorption.

🟢 22. Liver + Gallbladder + Bile

Liver

Produces bile

Gallbladder

Stores bile

Bile

Helps with fat digestion and absorption.

It emulsifies fat.

Emulsification:

Breaks large fat globules into much smaller droplets, making fat easier to digest and absorb.

⭐ Remember:

Liver = makes bile

Gallbladder = stores bile

Bile = helps digest/absorb fat

23. Enterohepatic Circulation

Bile is recycled.

Bile → small intestine → reabsorbed in ileum → returned to liver

A small amount that isn't reabsorbed leaves the body in feces.

⭐ Important:

Ileum = major site of bile reabsorption

24. Pancreas

The pancreas produces pancreatic juice.

It contains:

Sodium bicarbonate

• Neutralizes acidic chyme coming from the stomach

Pancreatic amylase

• Digests starch/carbohydrates

Pancreatic lipase

• Digests fat

Proteases

• Digest proteins

25. Sphincter of Oddi

The:

Bile duct + pancreatic duct

come together and empty into the:

Duodenum

The sphincter of Oddi controls this release.

⭐ Know:

Sphincter of Oddi → duodenum

26. Digestive Hormones ⭐⭐⭐

This table is VERY test-worthy:

27. The Big 3 Hormones to Know ⭐⭐⭐

If you don't have time to memorize everything, focus on:

Gastrin

Food in stomach → HCl + pepsinogen

CCK

Fat → pancreatic enzymes + bile

Secretin

Acidic chyme → bicarbonate

Easy memory trick:

CCK = fat → enzymes + bile

Secretin = acid → bicarbonate

28. Nutrient Absorption

After digestion, nutrients must cross the intestinal wall and enter the body.

There are 4 major absorption methods:

1. Passive diffusion

2. Facilitated diffusion

3. Active transport

4. Endocytosis

29. Passive Diffusion

Nutrients move:

High concentration → low concentration

No energy required.

Examples:

• Fats

• Water

• Some minerals

⭐ Think:

Passive = naturally moves down the concentration gradient

30. Facilitated Diffusion

Nutrients move:

High concentration → low concentration

BUT they need a carrier protein to cross the membrane.

Example:

• Fructose

⭐ Difference:

Passive diffusion = no carrier

Facilitated diffusion = carrier protein

Both move high → low.

31. Active Transport

Nutrients move:

Low concentration → high concentration

This requires:

• Energy

• Carrier proteins

Examples:

• Glucose

• Amino acids

⭐ Remember:

Active = energy required

32. Endocytosis

The cell engulfs a substance and forms a vesicle around it.

Think:

Cell membrane surrounds nutrient → brings it into cell

33. Absorption Isn't Only in the Small Intestine

The small intestine is the major site, but it is NOT the only place where absorption occurs.

For example, the stomach can absorb:

• Water

• Some fat

• Some alcohol

The large intestine also absorbs certain substances, especially:

• Water

• Some electrolytes

Test 2

Chapter 10 — Energy Balance & Weight Management

1. Energy Balance

Energy Balance

• Energy balance = relationship between energy intake and energy expenditure.

• Energy intake = calories consumed from food and beverages.

• Energy expenditure = calories the body uses.

Three States of Energy Balance

Positive Energy Balance Can Be Normal

Positive energy balance is appropriate during periods of growth:

• Pregnancy

• Infancy

• Childhood

• Adolescence

Negative Energy Balance

• Can be desirable for adults whose body fat is above healthy levels.

• Not recommended during growth stages.

2. Energy Intake

Measuring Energy in Food

Energy can be:

• Directly measured using a bomb calorimeter

• Estimated using nutrient databases

Calories from Macronutrients

• Carbohydrates = 4 kcal/g

• Protein = 4 kcal/g

• Fat = 9 kcal/g

3. Energy Expenditure

The body uses energy mainly for:

1. Basal metabolism (BMR)

2. Physical activity

3. Thermic effect of food (TEF)

A smaller contribution comes from:

• Thermogenesis

4. Basal Metabolic Rate (BMR)

BMR

BMR = minimum amount of energy needed to keep a resting, awake body alive.

Requires:

• Fasting

• Resting/awake state

BMR accounts for about 60–75% of total energy expenditure.

BMR Includes Energy Used For:

• Heart beating

• Breathing

• Brain and other organs functioning

• Maintaining basic body functions

RMR

Resting Metabolic Rate (RMR) is often used instead of BMR.

• RMR is about 6% higher than BMR.

• Used when a person has not been fully fasting or rested.

Estimated BMR

• Women: ~0.9 kcal/kg/hour

• Men: ~1.0 kcal/kg/hour

5. Factors Affecting Metabolic Rate

Metabolic rate is influenced by:

• Thyroid hormones

• Body composition

• Sex

• Body surface area

• Age

• Calorie intake

• Fever

• Stimulant drugs

• Pregnancy

• Lactation

• Recovery after exercise

6. Physical Activity

Physical activity can increase energy expenditure by about 25–40%.

Examples:

• Taking stairs instead of an elevator

• Walking instead of driving

• Standing instead of sitting

Important

Physical activity/inactivity has a major effect on total energy expenditure.

Inactivity is one factor contributing to increasing obesity rates.

7. Thermic Effect of Food (TEF)

TEF

Energy used to digest, absorb, transport, store, and metabolize food.

Usually accounts for about 5–10% of energy consumed.

TEF by Macronutrient

Meal Size

• Larger meals → higher TEF

8. Adaptive Thermogenesis

Adaptive Thermogenesis

• Production of heat by the body.

• Makes a small contribution to total energy expenditure.

• Includes involuntary physical activity.

Can be triggered by:

• Extreme cold

• Overfeeding

• Trauma

• Starvation

Examples:

• Fidgeting

• Shivering

• Maintaining muscle tone

• Holding the body upright

9. Measuring Energy Expenditure

Energy expenditure can be measured using:

Direct Calorimetry

• Measures the heat released by the body.

• Person is placed in an insulated chamber surrounded by water.

• Changes in water temperature show how much energy was used.

• About 60% of energy used by the body leaves as heat.

Indirect Calorimetry

• Measures oxygen consumed and carbon dioxide produced.

• There is a predictable relationship between gas exchange and energy use.

• Can estimate the energy cost of different activities.

Energy Expenditure Can Also Be Estimated Using:

• Height

• Weight

• Physical activity

• Age

10. Estimated Energy Requirements (EER)

EER estimates how much energy a person needs each day.

Important Conversions

• Pounds → kilograms: lbs × 0.4536

• Inches → meters: inches × 0.0254

EER Variables

• Age = years

• PA = physical activity

• WT = weight in kg

• HT = height in meters

11. Body Mass Index (BMI)

BMI

BMI = weight relative to height.

It is:

• Convenient

• Used for both men and women

• A general indicator of weight-related health risk

BMI Formula

Using kg and meters:

BMI = weight (kg) ÷ height² (m)

Using pounds and inches:

BMI = [weight (lb) × 703] ÷ height² (in)

BMI Classifications

Limitations of BMI

BMI:

• Does not directly measure body fat.

• Is not enough by itself to predict health or risk of death.

• Can be a marker of overweight without necessarily meaning excess body fat.

BMI is not appropriate for everyone, including:

• Children

• Teens

• Older adults

• Pregnant women

• Lactating women

12. Body Fat

Desirable Body Fat

Men: 8–24%

• Over 24% = considered obese

Women: 21–35%

• Over 35% = considered obese

• Women need more body fat partly because of reproductive functions.

13. Body Fat Distribution

Abdominal/Android Obesity

Excess fat around the abdomen is associated with increased risk of:

• Cardiovascular disease

• Hypertension

• Type 2 diabetes

Associated with:

• Males

• High-glycemic-load diets

• High alcohol intake

• Smoking

Waist Measurements

Increased risk when waist circumference is:

• Men: >40 inches

• Women: >35 inches

14. Measuring Body Fat

Highly Accurate Methods

Underwater weighing

• Measures body weight in water and in air.

• Uses body density to estimate body fat.

Air Displacement Plethysmography (BOD POD)

• Measures the amount of space the person's body occupies.

• Uses body density to estimate body fat.

DEXA

Dual-energy X-ray absorptiometry (DEXA)

• Considered the most accurate method listed in the notes.

• Estimates:

  • Body fat

  • Fat-free soft tissue

  • Bone minerals

Other Methods

Skinfold thickness

• Uses calipers to measure the fat layer under the skin.

Bioelectrical impedance

• Sends a small electrical current through the body.

• Greater electrical resistance = more adipose tissue.

15. Causes of Overweight & Obesity

Many factors can contribute:

• Eating behavior

• Gut microbiota

• Food composition

• Genetics

• Disease/medical conditions

• Medications

• Environment

• Neurodivergence

• Self-esteem

• Emotions

• Societal pressure

16. Hunger vs. Appetite

Hunger

Physiological drive to eat.

Controlled by:

• Hormones

• Nervous system

Appetite

Psychological desire to eat.

Can be influenced by:

• Social customs

• Time of day

• Mood

• Memories

• Sights and smells

• Environment

Important Difference

Hunger = physical need to eat
Appetite = psychological desire to eat

17. Satiety

Satiety

The feeling of being satisfied after eating and no longer having the drive to eat.

Internal and external signals work together to regulate eating.

We can also override these signals, such as:

• Ignoring hunger

• Eating dessert even when full

18. Hypothalamus

The hypothalamus is a key integration center for regulating hunger and satiety.

It communicates with:

• Endocrine system

• Nervous system

It responds to:

• Blood glucose levels

• Hormones

• Nervous system signals

When Signals Stimulate:

• Satiety center → stop eating

• Feeding centers → eat more

19. Hormonal Control of Satiety

Short-Term Hormones That Reduce Hunger

Released during digestion:

• PYY = Peptide YY

• GLP-1 = Glucagon-like peptide-1

• CCK = Cholecystokinin

After several hours:

• Macronutrient levels decrease.

• Satiety decreases.

Hormones That Stimulate Hunger

• Ghrelin

• Cortisol

Long-Term Satiety

Long-term satiety is influenced by:

• Body composition

• Amount of body fat

Leptin

• Produced by adipose tissue.

• Helps reduce food intake.

• Associated with body fat regulation.

20. Genetics & Obesity

More than 100 genes are associated with body weight.

About 20–30 "obesity genes" can affect:

• Eating

• Energy expenditure

• Energy storage

Genetic Risk

Approximate risk from notes:

• No obese parents → 10%

• One obese parent → 40%

• Two obese parents → 80%

Genetics Can Affect:

1. Body type

2. Metabolic rate

3. Hunger and satiety

Genes may account for approximately 40–70% of differences in body weight.

Thrifty Metabolism

A theory that some people may:

• Use energy more efficiently

• Store fat more readily

21. Environment & Obesity

Our genes haven't changed much over the past 50 years, but obesity has increased significantly.

Environment can influence:

• When we eat

• What foods we choose

• How much we eat

• Physical activity

Obesogenic Environment

An environment that makes it easier to:

• Consume excess calories

• Be physically inactive

Examples:

• Easy access to highly processed foods

• Advertising

• Limited access to healthy foods

• Limited safe spaces for physical activity

Genetic + Environmental Interaction

• Genetic predisposition does not guarantee obesity.

• Environment and lifestyle can influence how genetic tendencies are expressed.

22. Global Hunger & Malnutrition

Global agriculture produces about 2,940 kcal/person/day, theoretically enough to feed everyone.

However:

• About 820 million people are undernourished.

• About 2 billion experience micronutrient deficiencies.

• This is sometimes called "hidden hunger."

Most Affected

• Young children

• Women

23. Double Burden of Malnutrition

Overnutrition

• About 2 billion people worldwide are overweight or obese.

• Roughly 39% of adults.

Nutrition Transition

As countries become more Westernized, diets often shift toward:

• More meat

• Dairy

• Sugar

• Fat

• Alcohol

• Processed foods

And less:

• Whole grains

• Fruits

• Vegetables

Double Burden

Undernutrition + food insecurity + overnutrition + chronic disease can exist at the same time.

24. Food Security

Food Security

Having access to enough food for an active, healthy life at all times.

Food Insecurity

Not having consistent access to enough food for an active, healthy life.

Food insecurity can lead to:

• Poorer-quality diets

• Nutrient deficiencies

• Poor health

• Increased chronic disease risk

Levels

High food security

• No food-access problems.

Marginal food security

• Anxiety about food or possible shortages.

• Little/no change in food intake.

Low food security

• Reduced quality, variety, or desirability of diet.

Very low food security

• Disrupted eating patterns.

• Reduced food intake.

25. Food Insecurity in the U.S.

In 2023:

• 13.5% of U.S. households were food insecure.

• Almost 5% experienced very low food security.

Factors associated with food insecurity:

• Low-paying jobs

• Unemployment

• Lack of healthcare benefits

• High housing costs

• Family breakups

• Catastrophic illness

• Poverty

Important Connection

Food insecurity can sometimes increase obesity risk because people may rely on less expensive, less nutritious foods.

26. Health Consequences of Malnutrition

Insufficient energy intake can cause:

• Decreased physical and mental activity

• Slowed or stopped growth

• Muscle and fat wasting

• Weakened immune system

• Increased susceptibility to disease

27. Government Food Programs

SNAP

Supplemental Nutrition Assistance Program

• Provides food benefits through EBT cards.

WIC

Special Supplemental Nutrition Program for Women, Infants, and Children

• Helps low-income pregnant, breastfeeding, and postpartum women

• Infants

• Children up to age 5

Other Programs

• National School Lunch Program

• School Breakfast Program

• Child and Adult Care Food Program

• Meals for seniors

• Meals on Wheels

• Food distribution/emergency food programs

28. Global Undernutrition

Progress

• Undernutrition has decreased in developing regions.

• Underweight children decreased by nearly 50% in 20 years.

Ongoing Problems

• Millions of children remain underweight.

• Stunted growth remains common.

• Malnutrition increases vulnerability to:

  • Disease

  • Learning problems

29. Food Waste

About 1/3 of food produced worldwide is lost instead of eaten.

In the U.S., about 40% of food is wasted annually.

Causes

1. Farms lose food to pests/disease.

2. Imperfect food gets discarded during processing.

3. Stores throw away unsold perishables.

4. Restaurants prepare too much.

5. Consumers misunderstand food-date labels.

30. Treating Overweight & Obesity

Problem With Extreme Dieting

A common cycle is:

Drastic changes → quick results → difficult to maintain → willpower decreases → weight regained → repeat

Better Approach

Focus on long-term lifestyle changes.

A successful weight-loss program includes:

1. Sustainable control of energy intake

2. Regular physical activity

3. Control of problem behaviors

Successful Weight Loss

A program is considered successful when weight is:

• Lost and

• Maintained

31. Weight Cycling

About 1/3 of weight loss may be regained within a year after a diet ends.

Potential negative effects of repeated weight cycling include:

• Increased upper abdominal fat

• Lower self-esteem

• Lower HDL

• Reduced immune function

• Impaired thyroid function

32. Energy Intake & Weight Loss

Adipose tissue contains approximately 3,500 kcal/lb.

The notes give the traditional example:

To lose about 1 lb/week:

• Reduce energy intake by about 500 kcal/day, OR

• Increase activity by about 500 kcal/day, OR

• Combine both approaches.

Helpful Eating Pattern

Lower-energy-density foods tend to emphasize:

• Lower fat

• Higher fiber

33. Physical Activity & Weight Management

Burning an additional 100–300 kcal/day can contribute to steady weight loss.

Important factors:

• Duration

• Regularity

• Resistance exercise

Exercise can also improve:

• Bone density

• Self-esteem

• Sleep

Best approach: choose activities that are enjoyable and sustainable.

34. Controlling Problem Behaviors

Chain-Breaking

Separate behaviors that usually happen together.

Stimulus Control

Change the environment to reduce triggers for eating.

Cognitive Restructuring

Change the way you think about eating.

Contingency Management

Prepare for situations that might trigger overeating.

Self-Monitoring

Track:

• Food eaten

• When you eat

• Why you eat

• How you feel

• Physical activity

• Body weight

35. Fad Diet Red Flags 🚩

A diet may be a fad diet if it:

1. Promises a quick fix.

2. Claims one product/regimen is dangerous.

3. Sounds too good to be true.

4. Makes overly simple conclusions from complex research.

5. Is based on only one study.

6. Is rejected by scientific organizations.

7. Labels foods as simply "good" or "bad."

8. Relies heavily on testimonials.

9. Uses studies without proper peer review.

10. Ignores differences between people/groups.

36. Low-Carbohydrate Diets

Examples:

• Atkins

• South Beach

Why Rapid Weight Loss Happens Initially

Reducing carbohydrates causes:

• Less glycogen storage

• Less water stored with glycogen

• Initial weight loss is largely water, not just body fat.

Potential Concerns

Some high-fat versions may increase LDL cholesterol.

Long-term weight-loss results are not necessarily better than other balanced approaches.

37. Very Low-Fat Diets

Examples:

• Pritikin Diet

• Ornish's "Eat More, Weigh Less"

Characteristics:

• About 5–10% of energy from fat

• High carbohydrate

Limitations:

• Can be difficult to follow.

• Some people become bored.

• No significant advantage in weight loss.

38. Professional Treatment

Registered Dietitian (RD)

Doctors can refer patients to a registered dietitian for nutrition counseling.

Weight-Loss Medications

Some medications may:

• Reduce hunger by affecting brain chemicals.

• Reduce fat digestion.

Gastroplasty

• Reduces stomach capacity.

• May be recommended for people with morbid obesity (BMI >40).

39. Disordered Eating vs. Eating Disorders

Disordered Eating

Milder, short-term changes in eating patterns.

Can occur because of:

• Stress

• Illness

• Desire to change diet/body

May cause:

• Changes in body weight

• Nutritional problems

Usually does not require professional treatment.

Eating Disorders

More severe disturbances in eating behavior that can become life-threatening.

Common eating disorders:

• Anorexia nervosa

• Bulimia nervosa

• Binge-eating disorder

• OSFED

40. Eating Disorder Risk Factors

Causes can include:

• Genetics

• Cultural influences

• Psychological factors

• Stress

• Lack of coping skills

• Dysfunctional family relationships

• Drug abuse

About 85% develop during adolescence or early adulthood.

Without treatment, eating disorders can cause serious health complications.

41. Anorexia Nervosa

Characteristics

• Severe restriction of food intake

• Distorted body image

• Intense fear of gaining weight

• Extremely low body weight

• May deny or minimize the seriousness of the condition

Often begins during adolescence/young adulthood.

Physical Effects

Can include:

• Low body weight

• Low body temperature

• Slower metabolism

• Decreased heart rate

• Fatigue

• Anemia

• Dry/cold skin

• Low white blood cell count

• Hair loss

• Constipation

• Low potassium

• Menstrual changes

• Muscle/bone problems

42. Bulimia Nervosa

Main Pattern

Binge eating → compensatory behaviors

Compensatory behaviors can include:

• Vomiting

• Laxatives

• Diuretics

• Enemas

• Excessive exercise

People with bulimia may recognize that their behavior is problematic.

They may be at a normal or slightly above-normal weight, so it can be harder to recognize.

Possible Effects

• Tooth damage

• Low potassium

• Swollen salivary glands

• Digestive problems

• Damage to the esophagus

43. Binge-Eating Disorder (BED)

Characteristics include:

• Eating unusually large amounts of food

• Eating rapidly

• Eating even when not hungry

• Feeling uncomfortably full

• Often eating alone

• Feeling distress afterward

Possible triggers:

• Stress

• Depression

• Anxiety

Important

Binge-eating disorder and obesity are not automatically the same thing.

44. Treatment of Eating Disorders

Treatment may involve a multidisciplinary team, including:

• Physicians

• Registered dietitians

• Psychologists

• Other healthcare professionals

Goals include:

• Restore healthy eating patterns

• Address nutritional deficiencies

• Improve relationship with food

• Develop coping skills

• Correct misconceptions about food

• Improve body acceptance

• Regain control of daily life

Family therapy may also be helpful.

45. Preventing Eating Disorders

Discourage

• Restrictive dieting

• Skipping meals

• Fasting

• Weight-related negative comments

• Excessive focus on the scale

• Misconceptions about food

Encourage

• Eating when hungry

• Balanced nutrition

• Physical activity

• Family meals

• Self-acceptance

• Respect for different body types

• Healthy emotional expression

• Supportive environments

• Independence and responsibility

Chapter 5 — Carbohydrates

1. Carbohydrates Overview

What are carbohydrates?

• Organic compounds the body uses for energy.

• Made of:

  • Carbon

  • Hydrogen

  • Oxygen

• Plants make carbohydrates through photosynthesis.

• Carbohydrates provide 4 kcal/g.

Main Forms

• Sugar

• Starch

• Fiber

Main Energy Source

• Blood: glucose

• Liver & muscle: glycogen

AMDR

45–65% of daily calories should come from carbohydrates.

Food Sources

• Fruits

• Vegetables

• Dairy

• Cereals

• Bread

• Pasta

• Grains

• Desserts/sweets

2. Classification of Carbohydrates

Carbohydrates are classified by the number of sugar units.

Easy way to remember:

Mono = 1
Di = 2
Oligo = 3–10
Poly = many

3. Monosaccharides

Monosaccharides = one sugar unit.

Main ones:

• Glucose

• Fructose

• Galactose

Glucose

• Most abundant monosaccharide.

• Known as blood sugar.

• Basic unit of complex carbohydrates.

• Linked with other sugars in foods.

Fructose

• Found in:

  • Fruits

  • Vegetables

  • Honey

  • High-fructose corn syrup

• Sweetest monosaccharide.

Galactose

• Usually combined with glucose to form lactose.

• Found in milk sugar.

4. Sugar Alcohols

Examples:

• Sorbitol

• Mannitol

• Xylitol

Characteristics:

• Derived from monosaccharides.

• Provide fewer calories than regular sugar.

• Used in:

  • Sugar-free gum

  • Sugar-free foods

  • Diabetic foods

Sugar alcohols provide about 1.5–3 kcal/g.

5. Pentoses

Pentoses

• Monosaccharides containing 5 carbon atoms.

• Examples:

  • Ribose

  • Deoxyribose

They are not normally supplied by the diet.

Important:

• Ribose → RNA

• Deoxyribose → DNA

6. Disaccharides

Disaccharides = 2 monosaccharides linked together.

They are formed through a condensation reaction:

• Water is formed.

• A bond connects the sugars.

Three Important Disaccharides

Memorize:

Maltose → Maltase
Sucrose → Sucrase
Lactose → Lactase

7. Alpha vs. Beta Bonds

Alpha (α) bonds

• Usually digestible.

• Found in:

  • Starch

  • Glycogen

Beta (β) bonds

• Generally indigestible by human digestive enzymes.

• Found in:

  • Fiber

  • Some oligosaccharides

Key concept:

The type of bond helps determine whether a carbohydrate can be digested.

8. Oligosaccharides

Oligosaccharides

• 3–10 sugar units

• Examples:

  • Raffinose

  • Stachyose

Found in:

• Onions

• Cabbage

• Broccoli

• Whole wheat

• Legumes

Why can they cause gas?

• Contain beta bonds that humans cannot easily digest.

• They pass into the large intestine.

• Bacteria ferment them.

• This produces intestinal gas.

Beano

• Helps break down indigestible oligosaccharides.

9. Polysaccharides

Polysaccharides

• Complex carbohydrates.

• Made of hundreds to thousands of glucose molecules.

Three important types:

1. Starch

2. Glycogen

3. Fiber

10. Starch

Starch

• Major digestible polysaccharide.

• Main storage form of glucose in plants.

• Contains alpha bonds.

Two Types

Amylose

• Unbranched chain of glucose.

Amylopectin

• Highly branched.

• Branches allow enzymes to work more quickly.

• Can cause a faster increase in blood glucose.

Sources

• Potatoes

• Beans

• Bread

• Pasta

• Rice

• Legumes

11. Glycogen

Glycogen

• Storage form of carbohydrate in animals/humans.

• Made of glucose.

• Has alpha bonds.

• More highly branched than amylopectin.

• Can be broken down quickly for energy.

Main Storage Locations

• Liver

• Muscles

Easy comparison:

Plants → starch
Humans/animals → glycogen

12. Fiber

Total Fiber

Includes:

• Dietary fiber → naturally found in foods

• Functional fiber → added to foods

Fiber is an indigestible polysaccharide.

Because of its beta bonds, it passes through the small intestine mostly undigested.

In the large intestine:

• Bacteria ferment some fiber.

• Produces:

  • Short-chain fatty acids

  • Gas

13. Soluble vs. Insoluble Fiber

Insoluble Fiber

Does NOT dissolve in water.

Examples:

• Cellulose

• Hemicellulose

• Lignins

Sources:

• Seeds

• Whole grains

Main effects:

• Adds bulk to stool.

• Helps move material through the digestive tract.

• Helps prevent constipation.

Easy memory:

Insoluble = intestinal movement/bulk

Soluble Fiber

Dissolves in water.

Examples:

• Pectins

• Gums

• Mucilages

• Some hemicelluloses

Sources:

• Oat bran

• Fruits

• Legumes

• Psyllium

Main effects:

• Delays gastric emptying.

• Slows glucose absorption.

• Can reduce cholesterol absorption.

• Fermentable by bacteria.

Easy memory:

Soluble = slows absorption

14. Fiber and Bowel Problems

Insoluble fiber

Helpful for:

• Constipation

• Increasing stool bulk

• Faster intestinal movement

Soluble fiber

Can help slow digestion and absorption.

Remember:

Constipation → think insoluble fiber.

15. Sweeteners

Two major categories:

Nutritive Sweeteners

Provide calories.

Examples:

• Monosaccharides

• Disaccharides

• Sugar alcohols

Non-nutritive/Alternative Sweeteners

Provide little or no energy.

Examples:

• Saccharin

• Aspartame

• Sucralose

• Stevia

16. High-Fructose Corn Syrup (HFCS)

How it is made:

1. Cornstarch is broken down into glucose.

2. Enzymes convert some glucose into fructose.

3. HFCS contains about 55% fructose.

It is similar in sweetness to sucrose but is less expensive.

17. Sugar Alcohols

Examples:

• Sorbitol

• Mannitol

• Xylitol

Characteristics:

• 1.5–3 kcal/g

• Metabolized more slowly than sugars.

• Not easily metabolized by mouth bacteria.

• Do not promote dental caries as much as regular sugars.

Too much can cause:

Diarrhea

18. Alternative Sweeteners

Characteristics:

• Provide little/no energy.

• Do not promote dental caries.

• May be useful for people managing blood glucose or calorie intake.

• Safety is determined by the FDA.

ADI

Acceptable Daily Intake (ADI) = amount considered safe to consume daily.

19. Common Alternative Sweeteners

Saccharin

• About 300× sweeter than sucrose.

• Can have a bitter taste when heated/cooked.

Sucralose

• Made from sucrose.

• About 600× sweeter than sucrose.

• Can be used in cooking.

• Very little is absorbed.

Aspartame

• About 160–200× sweeter than sucrose.

• Made from:

  • Aspartic acid

  • Phenylalanine

• People with PKU should avoid it.

Stevia

• About 250× sweeter than sucrose.

• Comes from the Stevia plant.

20. Recommended Carbohydrate Intake

RDA

130 g/day

Why?

• Provides the minimum glucose needed by the:

  • Brain

  • Central nervous system

• Helps prevent excessive ketone production.

AMDR

45–65% of total calories from carbohydrates.

Best sources:

• Fiber-rich fruits

• Vegetables

• Whole grains

Limit:

• Added sugars

• Excess sweeteners

21. Recommended Fiber Intake

AI

14 g per 1,000 kcal

Other recommendations:

• Women under 50: 25 g/day

• Men under 50: 38 g/day

Fiber may help reduce the risk of:

• Diverticular disease

• Cardiovascular disease

• Other chronic diseases

Food Label Daily Value

28 g/day

22. Added Sugar

Recommendation:
Added sugar should be ≤10% of daily calories.

For a 2,000-calorie diet:

• 10% = 200 kcal

• 200 ÷ 4 = 50 g sugar

Current intake in notes:

About 13%

• 2,000 kcal → about 65 g

Regular 355 mL soda

• About 40 g sugar

23. Actual American Carbohydrate Intake

North Americans get about 50% of their calories from carbohydrates.

Major sources include:

• White bread

• Soft drinks

• Cookies

• Cakes

• Donuts

• Sugars

• Syrups

• Jams

• Potatoes

Problems

• Added sugar ≈ 13% of calories

• Fiber intake is 25–50% below recommendations.

• Only about 5% of the population meets daily fiber recommendations.

24. Functions of Carbohydrates

Digestible Carbohydrates

Broken down into glucose.

Functions:

1. Primary source of energy

2. Spare protein

3. Prevent ketosis

Indigestible Carbohydrates/Fiber

Important for:

• GI health

• Preventing constipation

• Blood glucose control

• Cholesterol management

• Weight management

May reduce risk of:

• Diabetes

• Cardiovascular disease

• Diverticular disease

25. Protein Sparing

Carbohydrates provide energy so the body doesn't have to use protein for energy.

If carbohydrate intake is too low:

Protein can be broken down to make glucose.

This process is called:

Gluconeogenesis = making glucose from non-carbohydrate sources.

26. Ketosis

The body normally needs about 50–100 g of carbohydrates/day to completely break down fats into carbon dioxide and water.

If carbohydrate intake is too low:

1. Insulin decreases.

2. Fatty acids are released from fat tissue.

3. Fat is not completely broken down.

4. Ketone bodies are produced.

5. This results in ketosis.

Can occur with:

• Untreated diabetes

• Very low-carbohydrate/high-fat diets

• Keto diets

• Atkins

• South Beach

27. Fiber Benefits

Fiber can:

• Increase fullness/satiety.

• Slow glucose absorption.

• Improve blood glucose control.

• Reduce cholesterol absorption.

• Add bulk to stool.

• Help prevent constipation.

• Support bowel health.

Soluble fiber

Especially important for:

• Slowing glucose absorption

• Reducing cholesterol absorption

28. Carbohydrate Digestion

Mouth

Salivary amylase

• Begins carbohydrate digestion.

• Breaks starch into:

  • Smaller polysaccharides

  • Disaccharides

Stomach

• Stomach acid inactivates salivary amylase.

Small Intestine

Digestion continues using:

• Pancreatic amylase

• Dextrinase

Then disaccharides are broken down by enzymes from the intestinal cells.

29. Disaccharide Digestion — VERY IMPORTANT

Memorize this!

Maltose → Maltase → 2 glucose

Sucrose → Sucrase → glucose + fructose

Lactose → Lactase → glucose + galactose

30. Large Intestine

Indigestible carbohydrates:

• Cannot be broken down by human digestive enzymes.

• Pass into the large intestine.

• Bacteria ferment them.

Products:

• Acids

• Gases

Some are excreted in feces.

31. Carbohydrate Absorption

Glucose & Galactose

• Absorbed by active transport.

• Transported with sodium (Na⁺).

• Requires ATP to maintain the sodium gradient.

Fructose

• Absorbed by facilitated diffusion.

• Absorbed more slowly than glucose and galactose.

Easy memory:

Glucose + Galactose → active transport

Fructose → facilitated diffusion

32. What Happens to the Sugars?

Fructose

Fructose → glucose
in absorptive cells and liver.

Galactose

Galactose → glucose
in the liver.

Glucose

Used by cells for energy.

If there is excess glucose:

Glucose → glycogen storage

If glycogen storage is full:

Excess glucose → body fat (adipose tissue)

33. Very-High-Fiber Diets

More than about 50–60 g/day may cause problems, especially if fluid intake is low.

Possible effects:

• Hard, dry stools

• Hemorrhoids

• Rectal bleeding

• Intestinal blockage

• Reduced mineral absorption

Potential nutrient deficiencies:

• Zinc

• Iron

34. Diets High in Simple Sugars

High intake can increase risk of:

Weight gain/obesity

Cardiovascular disease

Can contribute to:

• Increased triglycerides

• Increased LDL ("bad" cholesterol)

• Decreased HDL ("good" cholesterol)

Dental caries

Mouth bacteria metabolize sugar → produce acids → damage teeth.

35. Lactose Intolerance

Lactose intolerance = insufficient ability to digest lactose because of low lactase activity.

Lactase production can decrease after early childhood.

Primary Lactose Intolerance

• Insufficient lactase production.

Some people may tolerate:

• Hard cheeses

• Yogurt

• Acidophilus milk

Secondary Lactose Intolerance

• Temporary.

• Caused by damage to the small intestine.

• Damages lactase-producing cells.

36. Blood Glucose

Normal fasting blood glucose

70–100 mg/dL

Hyperglycemia

Blood glucose >126 mg/dL is classified as diabetes in the notes.

Possible symptoms:

• Hunger

• Thirst

• Frequent urination

• Weight loss

Hypoglycemia

Blood glucose <50 mg/dL in the notes.

Possible symptoms:

• Hunger

• Shakiness

• Irritability

• Weakness

• Headache

37. Blood Glucose Regulation

The two most important organs are:

Pancreas

Produces:

• Insulin

• Glucagon

Liver

Controls blood glucose by:

• Storing glucose as glycogen

• Releasing glucose when needed

38. Insulin

When is insulin released?

When blood glucose is high, especially after eating.

Insulin:

• Helps cells take up glucose.

• Promotes glucose use for energy.

• Promotes glucose storage.

• Lowers blood glucose.

Easy memory:

Insulin = glucose INTO cells → blood glucose goes DOWN

39. Glucagon

When is glucagon released?

When blood glucose is low, such as after skipping a meal.

Glucagon:

• Breaks down glycogen.

• Promotes gluconeogenesis.

• Raises blood glucose.

Easy memory:

Glucagon = glucose GOES up

40. Other Blood Glucose Hormones

Epinephrine & Norepinephrine

• Increase gluconeogenesis.

Cortisol & Growth Hormone

• Decrease glucose use by muscle cells.

41. Fed vs. Fasted State

Fed State = High Blood Glucose

Insulin is high.

The body:

• Uses glucose for energy.

• Stores glucose as glycogen.

• Makes fatty acids.

• Stores fat.

Think:

Fed = Store

Fasted State = Low Blood Glucose

Glucagon is high.

The body:

• Breaks down glycogen.

• Makes glucose through gluconeogenesis.

• Mobilizes fatty acids and glycerol for energy.

Think:

Fasted = Use stored energy

42. Metabolic Syndrome

Metabolic syndrome is diagnosed when 3 or more risk factors are present.

Factors include:

• Insulin resistance

• Abdominal obesity

• High triglycerides

• High LDL

• Low HDL

• High blood pressure

• Increased inflammatory proteins

Increases risk of:

• Type 2 diabetes

• Cardiovascular disease

Important

Lifestyle modification is key to reducing metabolic syndrome.

43. Diabetes Mellitus

Main types:

1. Type 1

2. Type 2

3. Gestational diabetes

Diabetes diagnosis can include:

• Fasting blood glucose ≥126 mg/dL

• Hemoglobin A1c ≥6.5%

44. Type 1 Diabetes

What happens?

The immune system destroys the insulin-producing cells of the pancreas.

Therefore:

• Little/no insulin is produced.

• Insulin injections are required.

Often begins in childhood.

Treatment

• Insulin therapy

• Nutrition therapy

• Regular meals/snacks

• Carbohydrate counting

• Individualized carbohydrate, protein, and fat intake

• Lower saturated fat/cholesterol

45. Type 1 Diabetes Complication: Ketosis

Without enough insulin:

• Fat is broken down.

• Ketones are produced.

• Ketones can cause dehydration and electrolyte/ion imbalance.

Severe complications can include:

• Coma

• Death

46. Type 2 Diabetes

Most common type

About 90% of diabetes cases in the notes.

Risk factors include:

• Inactivity

• Obesity

• Genetics

Insulin Resistance

Cells become less responsive to insulin.

Therefore:

• Glucose doesn't enter cells as easily.

• Glucose builds up in the blood.

• Causes hyperglycemia.

Treatment

• Healthy diet

• Physical activity

• Weight management

• Oral medications

• Insulin injections when needed

47. Diabetes Complications

Long-term diabetes can cause:

• Blindness

• Cardiovascular disease

• Kidney disease

• Nerve damage

• Diabetic peripheral neuropathy

48. Glycemic Index (GI)

Glycemic Index

Measures how a food affects blood glucose compared with a standard.

Influenced by:

• Starch structure

• Fiber content

• Food processing

• Protein in the meal

• Fat in the meal

Limitation

GI is based on a serving that provides 50 g of carbohydrate, which may not be the amount people normally eat.

49. Glycemic Load (GL)

Glycemic Load

Takes into account:

• Glycemic index

• Actual serving size

Therefore, GL may better represent the effect of a normal serving of food on blood glucose.

Easy difference:

GI = how quickly a food raises blood glucose

GL = GI + how much carbohydrate is actually eaten

Chapter 6 — Lipids

1. Lipids Overview

• Lipids are generally insoluble in water.

• They are less dense than water.

• They contain mainly carbon, hydrogen, and oxygen.

• Lipids include fats and oils.

• The three major types of lipids are:

  1. Triglycerides

  2. Phospholipids

  3. Sterols

2. Triglycerides

• Triglycerides are the most common lipid in food and the body.

• They are made of:

  • 1 glycerol backbone

  • 3 fatty acids

Diglyceride

• A triglyceride that has lost 1 fatty acid.

Monoglyceride

• A triglyceride that has lost 2 fatty acids.

Esterification

• The process of forming a triglyceride from glycerol and fatty acids.

• Forms ester bonds.

• It is a condensation reaction.

• Water is released.

De-esterification

• Breaks triglycerides apart into free fatty acids.

• It is a hydrolysis reaction.

• Water is used.

3. Fatty Acids

• Fatty acids are long carbon-hydrogen chains.

• One end contains a carboxyl group (COOH).

• The other end contains a methyl group (CH₃).

• Fatty acids differ based on:

  • Number of carbon atoms

  • Number of double bonds

  • Shape of the chain

Chain Length

Short-chain

• Fewer than 6 carbons

• Found in small amounts in butter

Medium-chain

• 6–10 carbons

• Coconut oil and palm oil

Long-chain

• 12+ carbons

• Beef, pork, lamb, and most plant oils

4. Saturated and Unsaturated Fatty Acids

Saturated Fatty Acids

• Have no carbon-carbon double bonds.

• Have the maximum amount of hydrogen.

• Usually solid at room temperature.

• Commonly found in animal fats.

Monounsaturated Fatty Acids

• Have 1 double bond.

• Usually liquid at room temperature.

Polyunsaturated Fatty Acids

• Have 2 or more double bonds.

• Usually liquid at room temperature.

Easy way to remember:

• Saturated = 0

• Monounsaturated = 1

• Polyunsaturated = 2+

5. Cis and Trans Fatty Acids

Cis

• Double bond causes the fatty acid chain to bend/kink.

Trans

• Fatty acid chain is straighter.

• Can be produced during hydrogenation.

Hydrogenation

• Adds hydrogen to liquid oils.

• Makes fats:

  • More saturated

  • More solid

  • More shelf-stable

• Can change the configuration of double bonds.

• Can create trans fatty acids.

Examples:

• Margarine

• Shortening

• Some processed foods

6. Food Sources of Triglycerides

Foods containing more fat:

• Animal fats

• Vegetable oils

• Coconut

• Avocado

• Nuts

• Seeds

Foods with little or no fat:

• Fruits

• Vegetables

• Fat-free milk

• Fat-free yogurt

• Breakfast cereals

• Yeast breads

7. Functions of Triglycerides

1. Compact energy storage

• Triglycerides are the body's main form of stored energy.

• Excess calories from:

  • Carbohydrates

  • Protein

  • Fat

  • Alcohol

• can be converted into triglycerides.

• They are very energy-dense.

2. Insulation and protection

Subcutaneous fat

• Fat underneath the skin.

• Helps maintain body temperature.

Visceral fat

• Fat around internal organs.

• Helps cushion and protect organs.

3. Fat-soluble vitamin absorption and transport

Fat helps the body absorb and transport:

• Vitamin A

• Vitamin D

• Vitamin E

• Vitamin K

4. Essential fatty acids

• Certain fatty acids are necessary for important functions such as:

  • Brain development

  • Retina development/function

8. Essential Fatty Acids

• Essential fatty acids cannot be made by the body.

• They must come from food.

Omega-3

• ALA (alpha-linolenic acid)

Omega-6

• LA (linoleic acid)

• The body cannot create certain double bonds needed to make these fatty acids.

9. Eicosanoids

Essential fatty acids can be used to make eicosanoids.

Examples:

• Prostaglandins

• Prostacyclins

• Thromboxanes

• Leukotrienes

• Lipoxins

They have many functions, including:

• Blood pressure

• Blood clotting

• Temperature regulation

• Sleep/wake cycle

• Inflammation

Omega-6 eicosanoids

• Can cause blood vessels to constrict.

• Can increase blood pressure.

Omega-3 eicosanoids

• Can cause blood vessels to dilate.

• Can decrease blood pressure.

• Can decrease inflammation.

10. DHA

DHA is an omega-3 fatty acid.

It is especially important during:

• Fetal development

• Infancy

Functions:

• Brain development

• Retina development

• Nerve transmission

• Communication between nerve cells

11. Phospholipids

• Phospholipids are similar to triglycerides.

• One fatty acid is replaced by a phosphate compound.

Structure

Phosphate head

• Hydrophilic = attracted to water

Fatty acid tails

• Hydrophobic = repel water

Easy memory:

Head = likes water
Tails = avoid water

12. Functions of Phospholipids

Cell membranes

• Phospholipids form the cell membrane.

• The membrane:

  • Forms the cell's outer covering.

  • Controls movement of substances into and out of the cell.

Emulsification

• Phospholipids can act as emulsifiers.

• They surround fat droplets and help fats mix with watery substances.

• Important for:

  • Fat digestion

  • Fat transport

Examples:

• Bile

• Lecithin

13. Phospholipid Sources

Phospholipids are:

• Made by the body

• Found in foods

Sources include:

• Egg yolks

• Wheat germ

• Peanuts

• Processed foods

• Ice cream

• Salad dressing

• Mayonnaise

• Creamy sauces

14. Sterols

• Sterols are a type of steroid.

• Their carbon atoms are arranged in multiple rings.

Main example:

Cholesterol

15. Functions of Cholesterol

Cholesterol is used to make:

• Sex hormones

• Active vitamin D

• Adrenal hormones

• Bile

• Cell membranes

Cholesterol in the body

According to your notes, the body produces about 800 mg/day.

Of that:

• About 400 mg → bile

• About 50 mg → steroid hormones

• Remaining cholesterol → plasma/lipoproteins

Dietary cholesterol absorption

• About 40–60% is absorbed.

16. Plant Sterols and Stanols

• Plants make sterols, but they do not make cholesterol.

• Examples:

  • Ergosterol

  • Beta-sitosterol

Sources:

• Fruits

• Legumes

• Nuts

• Vegetables

• Whole grains

Plant sterols/stanols:

• Are poorly absorbed.

• Compete with cholesterol for absorption.

• Can decrease cholesterol absorption.

17. Fat Digestion

Mouth

• Lingual lipase begins fat digestion.

• More important during infancy.

• Plays a smaller role in adults.

Stomach

• Gastric lipase continues fat digestion.

Small intestine

• Main site of fat digestion and absorption.

When fat enters the small intestine:

• It triggers release of CCK.

• CCK causes release of:

  • Bile

  • Colipase

18. Bile and Emulsification

• The liver produces bile.

• Bile helps emulsify fats.

Emulsification

• Breaks large fat droplets into smaller droplets.

• Gives digestive enzymes more surface area to work on.

• Makes fat digestion easier.

19. Fat Absorption

Fat is absorbed at the brush border of the small intestine.

The route depends on fatty acid chain length.

Short- and medium-chain fatty acids

• Enter the bloodstream/portal vein.

• Travel directly to the liver.

Long-chain fatty acids

• Enter the lymphatic system.

• Are re-esterified into triglycerides.

• Packaged into chylomicrons.

• Eventually enter the bloodstream.

20. Lipoproteins

Lipids do not dissolve well in blood, so they must be transported by lipoproteins.

Lipoproteins contain:

• Triglycerides

• Cholesterol

• Phospholipids

• Proteins

Major lipoproteins

Chylomicrons

• Mainly triglycerides.

• Carry dietary fat from the small intestine to body cells.

VLDL

• Mainly triglycerides.

• Carries fat made by the liver to body cells.

LDL

• Mainly cholesterol.

• Carries cholesterol to cells.

HDL

• Highest proportion of protein.

• Helps remove cholesterol from cells and carry it toward the liver.

Easy memory:

Chylomicron = dietary fat
VLDL = liver-made fat
LDL = cholesterol to cells
HDL = cholesterol away

21. Apolipoproteins

• Apolipoproteins are the protein portions of lipoproteins.

Functions:

• Identify lipoproteins.

• Help lipoproteins bind to cell receptors.

• Activate enzymes involved in lipid transport.

• Assist lipid-transfer enzymes.

Apo C-II

• Activates lipoprotein lipase (LPL).

22. Chylomicrons

Chylomicrons carry dietary fat.

Pathway:

Small intestine → lacteals → lymphatic system → bloodstream → body tissues

Lacteals

• Lymphatic vessels located in the small intestine.

Lipoprotein lipase (LPL)

• Located at cell membranes.

• Activated by Apo C-II.

• Breaks triglycerides in chylomicrons into free fatty acids.

• Fatty acids enter cells for:

  • Energy

  • Storage

After triglycerides are removed:

• The chylomicron remnant goes to the liver.

23. VLDL → IDL → LDL

The liver can make fat and cholesterol from:

• Carbohydrates

• Protein

• Fatty acids

The liver packages triglycerides and cholesterol into VLDL.

As VLDL loses triglycerides:

VLDL → IDL → LDL

VLDL

• Mainly triglycerides.

IDL

• Intermediate particle.

• Has lost some triglycerides.

LDL

• Loses additional triglycerides.

• Becomes mainly cholesterol.

24. LDL Removal

There are two main pathways for LDL removal.

1. Receptor pathway

• Cells have LDL receptors.

• The receptor recognizes Apo B-100.

• LDL enters the cell.

• LDL is broken down and its cholesterol can be used.

If a cell already has enough cholesterol:

• LDL receptor activity decreases.

• LDL can remain in the bloodstream.

LDL oxidation

• LDL can become oxidized by free radicals.

• Antioxidants can help protect against oxidation.

25. Scavenger Pathway

• Macrophages can take up LDL.

• Cholesterol can build up inside macrophages.

• These cholesterol-filled cells contribute to plaque formation.

This contributes to:

Atherosclerosis

Risk factors that encourage this process:

• Saturated fat

• Trans fat

• Refined sugars

• Smoking

• Diabetes

• Physical inactivity

26. HDL

HDL has the highest proportion of protein and is the most dense lipoprotein.

HDL is produced by:

• Liver

• Intestine

HDL:

• Travels through the bloodstream.

• Picks up cholesterol from cells.

• Can transfer cholesterol to other lipoproteins.

• Carries cholesterol back toward the liver.

• Helps remove cholesterol from the body.

• Helps protect LDL from oxidation.

• Helps slow development of cardiovascular disease.

27. Recommended Fat Intake

Total fat

20–35% of total calories

Saturated fat

Less than 10% of calories

Trans fat

As low as possible

Goal

• Eat mostly unsaturated fats.

• Limit saturated and trans fats.

28. Fat Grams Based on Calories

29. Essential Fatty Acid Recommendations

Omega-3

AI: 1.1–1.6 g/day

Omega-6

6.4 g/day

Omega-3 food sources

• Cold-water fish

• Walnuts

• Flaxseed

• Chia seeds

• Canola oil

• Soybean oil

• Flaxseed oil

Your notes recommend at least 2 portions of cold-water fish per week.

30. Essential Fatty Acid Deficiency

Possible effects:

• Diarrhea

• Slowed growth

• Delayed wound healing

• Delayed recovery from infections

• Flaky/itchy skin

31. Typical Fat Intake

Many people consume:

Too little:

• Monounsaturated fats

• Polyunsaturated fats

Too much:

• Saturated fat

• Trans fat

Common sources of saturated fat:

• Dairy

• Animal meat

Common sources of trans fat:

• Margarine

• Fried foods

• Baked goods

32. Health Concerns of Fat

High total fat

Associated with:

• Cardiovascular disease

• Obesity

• Some cancers

Excess omega-3

According to your notes, may:

• Impair immune function

• Cause uncontrolled bleeding

• Increase risk of hemorrhagic stroke

Excess omega-6

May:

• Worsen some inflammatory diseases.

• Be problematic when omega-6 intake is high compared with omega-3.

Trans fats

• Raise blood cholesterol.

• Increase cardiovascular disease risk.

• Lower HDL.

• Increase inflammation.

33. Cardiovascular Disease

CVD can begin with damage to a blood vessel.

Causes of inflammation/damage include:

• Smoking

• Diabetes

• Hypertension

• High LDL

• Homocysteine

• Viral/bacterial infections

Atherosclerosis

• Plaque builds up in artery walls.

• Arteries become:

  • Harder

  • Narrower

  • Less elastic

If blood flow becomes blocked, it can lead to:

• Heart attack

• Stroke

34. CVD Risk Factors

Nonmodifiable

• Age

• Sex

• Genetics

• Certain racial/ethnic risk patterns listed in your notes

Modifiable

• Obesity

• Poorly controlled diabetes

• High cholesterol

• High triglycerides

• Hypertension

• Smoking

• Physical inactivity

• Liver/kidney disease

• Low thyroid function

Numbers from your notes:

• Age >65 = risk factor

• Total cholesterol >200 mg/dL with LDL >160 mg/dL

• Triglycerides >150 mg/dL

35. Cholesterol Recommendations

General recommendation

≤300 mg/day

For CVD prevention

<200 mg/day

Desirable total cholesterol

≤200 mg/dL

36. CVD Prevention

Your notes recommend:

• Total fat: 20–35%

• Saturated fat: <10%

• Trans fat: as low as possible

• Polyunsaturated fat: <10%

• Monounsaturated fat: <20%

• Plant stanols/sterols: 2 g/day

• Cholesterol: <200 mg/day

• Soluble fiber: 20–30 g/day

• Maintain a healthy body weight.

• Get regular physical activity.

• Moderate simple sugar intake.

• Eat fruits and vegetables.

• Eat nuts.

• Use plant oils.

• Consume antioxidants such as vitamins C and E.

NUTR 2360 STUDY GUIDE

Chapters 10 & 3.1, 5, and 6

CHAPTER 10 & 3.1 — ENERGY BALANCE

1. Energy Balance

Energy balance = relationship between energy intake and energy exp enditure.

Energy equilibrium

• Energy intake = energy expenditure

• Body weight is generally maintained.

Positive energy balance

• Energy intake > energy expenditure

• Usually results in weight gain.

• Can be normal/necessary during:

  • Pregnancy

  • Infancy

  • Childhood

  • Adolescence

Negative energy balance

• Energy intake < energy expenditure

• Results in weight loss.

• Can be desirable for adults with excess body fat.

• Not recommended during periods of growth.

Easy memory:

Positive = more IN → weight UP
Negative = less IN → weight DOWN
Equilibrium = IN = OUT

2. Energy Intake

Energy intake = energy obtained from food and beverages.

How is it measured?

• Bomb calorimeter can directly measure the energy in food.

• Nutrient databases can estimate energy content.

Energy from nutrients

3. Energy Expenditure

The 3 primary uses of energy are:

1. Basal metabolic rate (BMR)

• About 60–75% of total energy expenditure.

• Largest component.

2. Physical activity

• About 25–40%.

• Varies greatly between people.

3. Thermic effect of food (TEF)

• About 5–10%.

• Energy used to digest, absorb, transport, store, and metabolize nutrients.

Adaptive thermogenesis

• Smaller contribution.

• Includes things like:

  • Fidgeting

  • Shivering

  • Maintaining muscle tone

  • Staying upright

TEF by nutrient

• Protein: 20–30%

• Carbohydrate: 5–10%

• Fat: 0–3%

Must remember:

BMR = 60–75%
Physical activity = 25–40%
TEF = 5–10%

4. BMR vs. RMR

BMR — Basal Metabolic Rate

The minimum energy needed to keep the body alive while:

• At complete rest

• Awake

• Fasting

Includes energy needed for:

• Heart

• Lungs

• Brain

• Other organs

RMR — Resting Metabolic Rate

• Similar to BMR.

• Usually about 6% higher than BMR.

• Conditions are less strict than BMR.

Easy:

BMR = stricter measurement
RMR = similar but slightly higher

5. Factors That Affect BMR

BMR is influenced by:

• Thyroid hormones

• Body composition

• Sex

• Body size/surface area

• Age

• Calorie intake

• Fever

• Stimulants

• Pregnancy

• Lactation

• Recovery after exercise

What increases BMR?

• More lean body mass

• Fever

• Pregnancy

• Lactation

• Stimulants

• Increased thyroid hormone activity

• Recovery after exercise

What decreases BMR?

• Aging

• Reduced calorie intake/starvation

• Loss of lean tissue

• Reduced thyroid activity

6. EER

EER = Estimated Energy Requirement

It estimates how much energy a person needs each day.

You do NOT need to memorize the formula.

Know the information needed:

• Age

• Sex

• Weight

• Height

• Physical activity level

Conversions

• Pounds → kilograms: lb × 0.4536

• Inches → meters: in × 0.0254

7. Hunger, Appetite, and Satiety

Hunger

A physiological drive to eat.

Appetite

A psychological desire to eat.

Satiety

The feeling of satisfaction that tells you to stop eating.

8. Regulation of Eating

The hypothalamus is the key integration site for regulation of satiety.

It receives signals from:

• Hormones

• Blood glucose

• Nervous system

Hormones that decrease hunger/increase satiety:

• PYY - Peptide YY

• GLP-1 - Glucagon-like peptide-1

• CCK - Cholecystokinin

Hormones that stimulate hunger:

• Ghrelin

• Cortisol

Long-term regulation:

Leptin

• Produced by adipose tissue.

• Helps decrease food intake.

• Signals information about body fat stores.

9. BMI

Formula

BMI = weight (kg) ÷ height (m²)

Or:

BMI = [weight (lb) × 703] ÷ height (in²)

Classifications

Important:

BMI does not directly measure body fat.

It is not appropriate as the main measure for:

• Children

• Teens

• Pregnant/lactating women

10. Body Fat: Men vs. Women

Desirable body fat

Men: 8–24%

Women: 21–35%

Women naturally require more body fat because of reproductive functions.

Obesity according to your notes:

• Men: >24%

• Women: >35%

11. Abdominal/Android Obesity

Abdominal obesity = excess fat around the abdomen.

It is associated with increased risk of:

• Cardiovascular disease

• Hypertension

• Type 2 diabetes

Waist circumference

Men: >40 inches

Women: >35 inches

12. Measuring Body Fat

Underwater weighing

• Measures body density.

• Uses the difference between body weight on land and underwater.

BOD POD

• Measures body density using air displacement.

DEXA

• Measures:

  • Body fat

  • Fat-free soft tissue

  • Bone mineral

• Most accurate method in your notes.

Skinfold calipers

• Measures thickness of subcutaneous fat at specific body sites.

Bioelectrical impedance

• Sends a small electrical current through the body.

• Fat resists electrical flow more than lean tissue.

• Greater resistance = more adipose tissue.

13. Factors Affecting Body Composition

Body composition can be influenced by:

Genetics

• More than 100 genes are associated with body weight.

• Genes influence:

  • Body type

  • Metabolic rate

  • Hunger

  • Satiety

Eating behavior

• What, when, and how much a person eats.

Food/environment

An obesogenic environment encourages:

• High-calorie food intake

• Physical inactivity

Gut microbiota

• Gut bacteria can influence energy use and body weight.

Disease and medications

• Some illnesses and medications can affect body weight/body composition.

Emotions and self-esteem

• Stress and emotions can influence eating behavior.

Neurodivergence/social environment

• Can influence eating patterns and activity.

Important:

Genetic predisposition is NOT destiny.

14. Food Security

Food security = having consistent access to enough food for an active, healthy life.

Food insecurity

= lack of consistent access to enough food.

Levels

High

• No problems accessing food.

Marginal

• Anxiety about food running out.

• Little/no change in intake.

Low

• Reduced quality/variety of food.

• Little/no reduction in amount eaten.

Very low

• Eating patterns are disrupted.

• Food intake is reduced.

15. Effects and Contributors of Food Insecurity

Food insecurity can contribute to:

• Poor nutrition

• Malnutrition

• Greater obesity risk

• Reduced physical/mental functioning

Contributors:

• Low wages

• Unemployment

• Lack of healthcare benefits

• High housing costs

• Family breakups

• Catastrophic illness

Populations especially affected:

• Low-income households

• Young children

• Women

• People experiencing poverty/food insecurity

16. Weight Loss

Adipose tissue

1 pound of adipose tissue ≈ 3,500 kcal

Traditional calculation:

• 500 kcal/day deficit ≈ 1 lb/week

Ways to create a deficit:

• Reduce energy intake.

• Increase physical activity.

• Combine reduced intake + activity.

Your notes also mention:

• 100–300 extra kcal/day burned through activity can contribute to steady weight loss.

17. Reliable Weight Loss

Successful long-term weight management involves:

• Sustainable energy intake control

• Regular physical activity

• Changing problem behaviors

• Self-monitoring

• Stimulus control

• Cognitive restructuring

• Enjoyable activities

• Maintaining the weight loss

Important:

Success = losing weight AND maintaining the loss.

18. Fad Diet Red Flags

Be suspicious of diets that:

• Promise extremely rapid weight loss

• Claim a "quick fix"

• Say results are guaranteed

• Use "too good to be true" claims

• Make overly simplistic conclusions

• Rely on one study

• Use testimonials instead of scientific evidence

• Promote good/bad food lists

• Ignore individual differences

• Use non-peer-reviewed research

• Have been rejected/refuted by scientific organizations

19. Low-Carb and Very-Low-Fat Diets

Low-carb diets

Examples:

• Atkins

• South Beach

Initial rapid weight loss is often partly water loss because glycogen stores decrease.

Approximately:

1 g glycogen → 3 g water

Very-low-fat diets

Examples:

• Pritikin

• Ornish

Usually:

• 5–10% of calories from fat

• High carbohydrate

Can be difficult to maintain long-term.

20. Disordered Eating vs. Eating Disorders

Disordered eating

• Less severe.

• Often temporary.

• Can result from:

  • Stress

  • Illness

  • Appearance concerns

  • Health concerns

Eating disorders

• More severe.

• Involve serious distortions in eating/body image.

• Can be life-threatening.

• Usually require professional treatment.

21. Causes/Risk Factors of Eating Disorders

Possible factors:

• Genetics

• Cultural pressure

• Psychological factors

• Stress

• Poor coping skills

• Dysfunctional family relationships

• Substance abuse

• Restrictive dieting

Your notes say many begin during adolescence or early adulthood.

22. Anorexia Nervosa

Characteristics:

• Severe restriction of food intake.

• Intense fear of gaining weight.

• Distorted perception of body size/shape.

• Significant weight loss.

• Denial or difficulty recognizing the seriousness of the condition.

Physical effects

Can affect:

• Heart

• Bones

• Hormones/reproductive function

• Immune system

• Normal growth and development

Treatment

Usually requires a multidisciplinary team, such as:

• Physician

• Registered dietitian

• Mental health professional

• Family/support system

Goals:

• Restore adequate nutrition.

• Restore healthy body function.

• Address distorted thoughts about food/body.

• Develop healthier coping skills.

23. Bulimia Nervosa

Characteristics:

• Repeated episodes of binge eating.

• Followed by compensatory behaviors.

• Body weight may be normal or slightly above normal.

Physical effects

Can include:

• Dental problems

• Electrolyte abnormalities

• Digestive problems

• Salivary gland enlargement

• Damage to the digestive tract

Treatment

• Multidisciplinary treatment.

• Restore regular eating patterns.

• Address binge/compensatory behavior.

• Psychological treatment.

• Nutrition counseling.

24. Binge-Eating Disorder

Characteristics:

• Repeated episodes of eating unusually large amounts.

• Feeling unable to control eating.

• Eating rapidly.

• Eating when not hungry.

• Eating until uncomfortably full.

• Often eating alone.

• May be associated with stress, anxiety, or depression.

Important:

Binge-eating disorder is not the same as simply overeating occasionally.

Treatment

• Nutrition counseling

• Psychological treatment

• Regular eating patterns

• Coping strategies

• Addressing triggers

🟩 CHAPTER 5 — CARBOHYDRATES

1. What Are Carbohydrates?

Carbohydrates are organic compounds used primarily for energy.

They contain:

• Carbon

• Hydrogen

• Oxygen

Forms:

• Sugar

• Starch

• Fiber

Energy:

4 kcal/g

2. Simple vs. Complex Carbohydrates

Simple carbohydrates

• Monosaccharides

• Disaccharides

Complex carbohydrates

• Oligosaccharides

• Polysaccharides

3. Monosaccharides

One sugar unit.

Glucose

• Main blood sugar.

• Most abundant monosaccharide.

• Basic building block of complex carbohydrates.

Fructose

• Found in:

  • Fruits

  • Vegetables

  • Honey

  • High-fructose corn syrup

• Sweetest monosaccharide.

Galactose

• Combines with glucose to form lactose.

• Mainly found as part of milk/lactose.

4. Disaccharides

Two sugar units.

Maltose

Glucose + glucose

Enzyme:
Maltase

Sucrose

Glucose + fructose

Enzyme:
Sucrase

Lactose

Glucose + galactose

Enzyme:
Lactase

Must memorize:

5. Oligosaccharides

• 3–10 sugar units

• Examples:

  • Raffinose

  • Stachyose

Found in:

• Onions

• Cabbage

• Broccoli

• Whole wheat

• Legumes

They contain beta bonds, which humans cannot digest.

Bacteria in the large intestine ferment them → gas.

6. Polysaccharides

Many sugar units.

Examples:

• Starch

• Glycogen

• Fiber

Starch

Main storage carbohydrate in plants.

Glycogen

Storage carbohydrate in animals/humans.

Fiber

Mostly indigestible carbohydrate.

7. Amylose vs. Amylopectin

Both are forms of starch.

Amylose

• Unbranched

• Mostly straight chain.

Amylopectin

• Highly branched

• Branching gives enzymes greater access.

• Can cause a faster rise in blood glucose.

Both contain alpha bonds.

8. Glycogen

• Main carbohydrate storage form in animals.

• Stored mainly in:

  • Liver

  • Muscles