Nutrition V
Chapter 8 Introduction
Potential energy= stored/waiting to happen
Kinetic energy= in motion
Potential in- carbs, lipids, proteins, alcohol
Turns into thermal energy/heat
1 kcal= 1000 calories
Kilojoule (kj) 1 kcal= 4.18 kj
Nutrition facts label
Chapter 8 The Atom
Atoms- fundamental unit of matter composed of protons and neutrons and electrons
Protons and neutrons- form the nucleus while electrons orbit in electron cloud
Energy and stability of atoms
-atoms are the most stable when electrons orbit in pairs
-chemical bonds form when atoms share or exchange electrons to get stability
Chemical reactions and Free radicals
chemical reactions- movement of electrons between atoms
Free radicals- (e.g. superoxide) are atoms or molecules with unpaired electrons, highly reactive and damaging to cells
Metabolism Overview:
-metabolism- encompasses all chemical reactions needed for cellular functions
-catabolism- breaking down molecules to release energy
-anabolism- building larger molecules and requires energy
Nutrient Catabolism Stages
-glycolysis- breakdown of glucose into pyruvate, yielding ATP
-citric acid cycle- acetyl-CoA, enters cycle, producing NADH, FADH2, and ATP equivalents
- electron transport chain- electron transfer generates ATP via oxidative phosphorylation
Energy Efficiency and Heat Production
-catabolism 30-40% efficient- some energy released as heat
-heat production- vital for maintaining body temperature
Anabolism and Macromolecule Synthesis
-anabolic pathways- use intermediates from catabolic processes to build macromolecules like proteins, RNA, DNA, and energy storage molecules
Regulation of Metabolic Pathways
-regulated by energy status, hormones
-excess nutrients can be stored as glycogen or fat, depending on energy needs
Clinical Relevance
-marasmus-severe malnutrition leading to muscle wasting and compromising bodily functions due to energy deficiency
-gluconeogenesis- synthesis of glucose from amino acids during fasting to maintain blood glucose levels
Storage of Energy
-excess glucose is stored as glycogen in liver and muscles
-further excess is converted to fat (lipogenesis) stored in adipocytes
Chapter 8: Weight Management
Obesogenic Environment
- environment promoting increased food intake, unhealthy foods and no activity
-2009 33% of adults 16% kids were obese
Health Consequences
-increased risks: cardiovascular disease, type 2 diabetes, certain cancers
Factors Contributing to Obesity
-fast food industry
-portion sizes- increasing since 1960’s: 1990’s trend “supersize”
-technological changes- increase in vehicles and sedentary lifestyles
-environmental influences- urbanization and less walkable cities
Combat Obesity
-individual level: whole foods, smaller portions, more activity, low calorie options
-community level: support local farms, community clean ups
-national level: support policies for walkability, campaigns against obesity, subsidies for healthy foods
Understanding Energy Balance
-calories consumed should equal calories expended to maintain body weight
-Estimated Energy Requirement(EER)- calculated based on age, sex, weight, height, physical activity level. Used to estimate daily energy needs for weight maintenance
Factors Influencing Total Energy Expenditure (TEE)
-basal metabolic rate (BMR)- energy expended at rest to maintain basic bodily functions
-influenced by body size, age, sex, and genetics
-thermic effect of food- 10% of TEE
-physical activity- 15-30% of TEE
Chapter 8 Factors Affecting Energy Intake
Physiological regulation of appetite
-appetite is controlled by the hypothalamus in the brain, influenced by hormonal and neural signals
-hunger and satiety are communicated through mechanical and chemical signals from the periphery
-stomach contractions and expansions send signals to the hypothalamus, influencing feelings of hunger and fullness
Role of hormones in appetite regulation
-leptin, produced by fat tissue signals satiety to the hypothalamus
-overweight people could be leptin resistant reducing it effects
-hormones from the stomach communicate fullness of hunger to the brain
Nutrients and appetite
-nutrient levels in the blood affect hunger and satiety centers in the hypothalamus
-cravings for salty and sweet foods have physiological roots linked to nutrient levels
Genetic and environmental influences
-genetics influence body fatness and weight, affecting food intake
-interaction between genetics and environment plays a role in obesity
Chapter 8 Factors Impacting Energy Expenditure
Difficulty in weight management
-set point theory
-each person has a “set point” for body fatness regulated by the brain
-changes in energy intake are triggered to maintain body fat in target range
-after dieting most people return to original weight due to “set point”
-settling point system
-considers obesogenic environments role in weight gain
-body fatness adjusts to energy intake, increased food availability or sedentary behaviors can lead to weight gain
-criticized for overgeneralizing individual responses to diet and exercise changes
Genetics and environment interaction
-prenatal nutrition can impact later in life weight and disease risk
-sedentary behavior and weight
-energy expenditure less than 1.5 times resting energy while sitting
-common in North America, contributes to reduced energy expenditure
Social factors affecting energy expenditure
-modern conveniences (elevators/cars)
-office jobs and high stress jobs limit exercise time
-modernization, urbanization, industrialization linked to rising obesity rates
Health risks
-over 25 BMI= risk of heart disease, type 2 diabetes, stroke and cancers
-increased intake of energy dense foods
Chapter 8 Recommendations for Weight Management
Healthy eating pattern that accounts for all foods and beverages within an appropriate calorie level includes:
-fat free/low fat dairy
-oils
-variety of protein foods
-variety of fruits and whole fruits
-grains in which half are whole grains
-variety of vegetables from all subgroups
A healthy eating pattern limits
-sodium
-added sugars
saturated/trans fats
Other recommendations to help limit:
-consume alcohol in moderation 1 drink per day for women 2 drinks for men
-consume less than 2,300 mg sodium per day
-consume less than 10% of calories per day from saturated fats
-consume less than 10% of calories from added sugars
Moderate activities
-ballroom dancing/line dancing
-biking (level ground)
-canoeing
-gardening
-baseball/softball/volleyball
Vigorous activities
-aerobic dance
-biking (more than 10 mph)
-heavy gardening (digging and hoeing)
-swimming
-fast dancing
Small amounts of aerobic activity are most beneficial
Chapter 12 Understanding Dietary Reference Intakes
Dietary Reference Intake (DRI)
Purpose: recommendation levels for certain nutrients. An umbrella term for four reference values
Function: used as a guide for planning, assessing, and setting nutritional recommendations for the majority of the healthy population
Adequate Intake (AI)
Purpose: created for nutrients when there is insignificant consistent scientific evidence to set EAR for entire population
Function: used as a nutrient-intake goals for a given nutrient
Tolerable Upper Intake Levels (UL)
Purpose: Made to help distinguish healthful and harmful nutrients. Developed in part as a response to growing usage of dietary supplements.
Function: Indicates highest level of continuous intake of a certain nutrient that may be taken without causing health problems.