chapter 9 General Nutrition 200

Main health risk of underweight

Increased risk of death during famine or disease due to low fat stores.

Main health risk of excessive body fat

Increased risk of chronic diseases such as diabetes, heart disease, and hypertension.

Percentage of U.S. adults overweight or obese

69%

Percentage of U.S. adults obese

42.4%

Percentage of U.S. adults severely obese (BMI ≥ 40)

9.2%

Percentage of U.S. adults underweight (BMI < 18.5)

1.5%

Percentage of U.S. children and adolescents obese

18%

Body composition

The proportion of muscle, bone, fat, and other tissues in the body.

Adipokines

Hormones produced by fat tissue that regulate inflammation and energy use.

Effect of obesity on adipokines

Increases inflammation and insulin resistance.

Central obesity

Excess fat in the abdomen and around the trunk.

Subcutaneous fat

Fat stored directly under the skin.

Visceral fat

Fat stored within the abdominal cavity around internal organs.

Metabolic syndrome

A combination of central obesity and chronic diseases.

Apple profile of fat distribution

Men and postmenopausal women.

Pear profile of fat distribution

Women in reproductive years.

BMI formula (metric)

BMI = weight (kg) / height (m)²

BMI formula (imperial)

BMI = weight (lbs) × 703 / height (in)²

BMI range for underweight

< 18.5

BMI range for normal weight

18.5 - 24.9

BMI range for overweight

25 - 29.9

BMI range for obesity

≥ 30

Waist circumference risk for men

≥ 40 inches (102 cm)

Waist circumference risk for women

≥ 35 inches (88 cm)

Waist circumference indication

Degree of central obesity and related disease risk.

Indicators for obesity risk

BMI, waist circumference, and disease risk profile.

Main methods to assess body fat

Waist circumference, skinfold test, and DEXA scan.

Skinfold test

Measures thickness of skin and subcutaneous fat.

DEXA

Used for measuring body fat distribution and bone density.

Ideal body fat level

Enough to support health, not for appearance.

Body fat loss improving health risks

5-10% of body weight.

BMI indicating urgent need for weight loss

≥ 30 or 25-29.9 with risk factors.

Common diseases associated with obesity

Type 2 diabetes, heart disease, hypertension, gallstones, stroke.

Relationship between obesity and inflammation

Obesity causes inflammatory adipokines and insulin resistance.

Can a person with obesity be healthy?

Possibly, if metabolic indicators are normal.

Can a person with normal weight be unhealthy?

Yes, if they have metabolic diseases or central fat.

Energy balance

Energy in = Energy out.

When energy in > energy out

Fat storage increases.

When energy in < energy out

Fat stores are used for energy.

Three components of energy out

Basal metabolism, voluntary activity, thermic effect of food.

Basal metabolic rate (BMR)

BMR percentage of total energy

60-70%

Factors affecting BMR

Age, gender, body size, genetics, temperature, hormones, activity level.

Thermic Effect of Food (TEF)

Energy required to digest, absorb, and process food (~10% of meal energy).

Age effect on energy need

BMR decreases about 5% per decade after age 30.

Factors used in estimating energy requirements (EER)

Age, gender, weight, height, and physical activity.

Physical activity levels for EER

Sedentary, moderately active, and active.

Estimating daily calories for men

EER ± 200 calories.

Estimating daily calories for women

EER ± 160 calories.

Hunger hormone

Ghrelin.

Production site of ghrelin

The stomach.

Appetite

The psychological desire for food.

Hunger

The physiological need for food.

Satiation

The feeling of fullness during a meal that leads to stopping eating.

Satiety

The lasting feeling of fullness between meals.

Appetite suppressing hormone

Leptin.

Macronutrient with greatest satiating effect

Protein.

Nutrients promoting longer satiety

Protein, complex carbs, and soluble fiber.

Set-Point Theory

The body resists weight change by adjusting metabolism to maintain a set weight.

Thermogenesis

Generation of heat during metabolism.

Brown Adipose Tissue (BAT)

Fat that burns calories to produce heat.

Intestinal microbiota theory of obesity

Certain gut bacteria affect body weight and fat storage.

Role of gut bacteria in weight

Affect energy extraction, storage, and inflammation.

Genetics contribution to obesity risk

30-70% chance if one parent is obese.

Environmental cues to overeating

Large portions, stress, food availability, and variety.

Neurotransmitter linked to food pleasure

Dopamine.

Physical inactivity contribution

Lower energy expenditure and weight gain.

Food deserts

Areas lacking access to affordable, healthy foods.

National goals to reduce obesity

Promote activity, improve food access, and create healthy environments.

Calculating calorie cost of an activity

Activity factor × weight (lbs) × minutes.

Minutes of moderate activity to prevent weight gain

150-250 minutes.

Minutes per week to maintain weight loss

>250 minutes.

Calories equal to one pound of body fat

3,500 calories.

Recommended rate of weight loss

1-2 pounds per week.

Weight loss improving health outcomes

3-5% of body weight.

Key strategies for healthy weight loss

Balanced diet, physical activity, and behavior modification.

Calorie reduction recommended for BMI ≥ 35

Reduce up to 1000 kcal/day.

Calorie reduction recommended for BMI 25-35

Reduce 500-750 kcal/day.

Safe calorie range for men during weight loss

1500-1800 kcal/day.

Safe calorie range for women during weight loss

1200-1500 kcal/day.

Healthy eating habits for weight loss

Eat more fruits, vegetables, legumes, whole grains, and lean proteins.

Foods to be reduced for weight loss

Saturated fat, sodium, refined grains, and sugary foods.

Why should portion size be controlled?

To prevent excess calorie intake.

Low energy density foods

Foods high in water and fiber, low in fat.

High energy density foods

Foods high in fat and low in water (e.g., fried foods).

Difference between energy density and nutrient density

Energy density = calories per gram; nutrient density = nutrients per calorie.

Snacks for weight control should include

Low solid fats and low added sugars.

Best beverages for weight loss

Water, low-fat milk, unsweetened tea.

How does alcohol affect weight?

Adds empty calories and promotes fat storage.

Calories provided by alcohol per gram

7 kcal/gram.

Nonnutritive sweeteners

Artificial sweeteners that provide few or no calories.

Are nonnutritive sweeteners risk-free?

Effects on gut microbiota and appetite are under study.

Advantages of prepared meal plans

Convenient and support calorie control.

Disadvantage of prepared meal plans

Expensive and may not teach long-term eating habits.

What happens to the body during fasting?

Liver glycogen is used up; body uses protein for glucose.

Why can't fat directly provide glucose?

Fatty acids cannot be converted to glucose.

Ketone bodies

Compounds made from fat during low carb intake or fasting.

How long can an average person survive without food using fat stores?

6-8 weeks.

Side effects of prolonged fasting

Nutrient loss, slowed metabolism, acid-base imbalance, and overeating rebound.

What happens to excess dietary protein?

Converted to fat after removing nitrogen.