Ch. 7 Energy Balance (still updating)

What is energy balance?

The state in which energy intake equals energy expended through basal metabolism, physical activity, and thermic effect of food

What is positive energy balance?

Energy intake exceeds expenditure, leading to weight gain

What is negative energy balance?

Energy expenditure exceeds intake, leading to weight loss

How is caloric content of food measured?

Using a bomb calorimeter that burns food to measure heat released; 1 kcal raises temperature of 1 kg water by 1°C

What are the three main components of total energy expenditure?

Basal metabolism, physical activity, and digestion/absorption/processing of food

What is thermogenesis?

The metabolic process of burning calories to produce heat

What is adaptive thermogenesis (AT)?

Heat production in response to changes such as cold exposure or diet; includes shivering

What is brown adipose tissue and what is its role?

A metabolically active fat tissue that releases energy as heat instead of ATP; important in thermogenesis

What is basal metabolic rate (BMR)?

Minimum calories required to maintain vital body functions in a fasting, resting, warm, quiet state

What proportion of total energy needs does basal metabolism account for?

Approximately 60%–80% of total energy needs

What is resting metabolic rate (RMR)?

Slightly higher than BMR, measured when not fasting

How does very low-calorie intake affect basal metabolism?

Decreases it by 10%–20% (≈150–300 kcal/day) as the body conserves energy

How does metabolism change across the lifespan?

Peaks at about 1 year of age, declines until 20, stabilizes from 20–60, declines again in older adulthood

What is the most significant contributor to basal metabolic rate?

Lean body mass (LBM)

What is NEAT (non-exercise activity thermogenesis)?

Energy burned for unplanned daily activities such as fidgeting, walking to the kitchen, climbing stairs

What is EAT (exercise-activity thermogenesis)?

Energy burned during planned exercise such as running, cycling, lifting weights

What is the thermic effect of food (TEF)?

Energy used to digest, absorb, and metabolize food; ≈8%–15% of total energy intake

Which macronutrient has the highest TEF?

Protein (followed by carbohydrate, then fat)

What is direct calorimetry?

Measures body heat output in an insulated chamber; accurate but expensive

What is indirect calorimetry?

Estimates energy expenditure by measuring oxygen consumed and carbon dioxide produced

What is the Estimated Energy Requirement (EER)?

Average dietary energy intake predicted to maintain energy balance based on age, sex, weight, height, and activity level

What is the EER for a 25-year-old active male, 175 cm tall, 70 kg?

≈ 2989 kcal/day

What is a healthy body weight?

Weight determined with a health professional considering BMI, medical history, fat distribution, activity, diet, family history, and current health

What is BMI and how is it calculated in metric units?

BMI = weight (kg) ÷ height² (m²)

What is BMI using U S units?

BMI = [weight (lbs) × 703] ÷ height² (in²)

What are the BMI categories for adults?

Underweight < 18.5; Normal 18.5–24.9; Overweight ≥ 25; Obese ≥ 30 (Class I = 30–34.9; Class II = 35–39.9; Class III ≥ 40)

What is average healthy body-fat percentage?

Females 25%–31%, males 18%–24%

What body-fat percentage is considered obese?

Females > 32%, males > 25%

How does underwater weighing (hydrostatic) assess body composition?

Compares body weight in air vs. underwater to calculate body density; fat is less dense than lean tissue

What is Bod Pod® (air-displacement) densitometry?

Measures air displaced in a sealed chamber to estimate body density and composition

What does skinfold measurement assess?

Thickness of subcutaneous fat at several sites using calipers to estimate total body fat

What is bioelectrical impedance analysis (BIA)?

Sends a low-level electrical current through the body; resistance correlates with body-fat percentage

What is dual-energy X-ray absorptiometry (DXA)?

Highly accurate scan for body-fat percentage and bone density; minimal radiation exposure

What waist circumference indicates elevated health risk?

40 inches for males, > 35 inches for females

How does fat distribution affect health risk?

Upper-body (android) fat is linked to higher risk of obesity-related diseases than lower-body (gynoid) fat

Name five factors that encourage excess body fat.

Age, low BMR, genetics, physical inactivity, and high ratio of fat to lean tissue (others include menopause, social and behavioral factors)

What do twin studies suggest about nature’s role in obesity?

Identical twins raised apart still show similar weight-gain patterns and fat distribution

What environmental factors (nurture) contribute to obesity?

Learned eating behaviors, low activity, poverty, stress, excess screen time, sleep loss, energy-dense foods, eating out, lack of care

What is weight bias and how can it harm health?

Negative attitudes toward higher-weight individuals; linked to depression, stress-hormone increase, avoidance of medical care, social isolation

What is the average daily calorie need for females and males?

Females ≈ 1800–2400 kcal/day; males ≈ 2400–3000 kcal/day

How many calories are stored in 1 pound of fat?

≈ 3500 kcal

What daily energy deficit is typically needed to lose 1 pound of fat per week?

≈ 500 kcal/day

What eating pattern is most successful for long-term weight management?

Primarily plant-based, high-fiber dietary patterns

List two strategies to control hunger.

Eat high-fiber snacks and lean-protein foods; eat slowly and drink water between meals

What is the initial pattern of weight loss during a program?

Faster at first due to loss of water and some fat; slows as lean mass increases with exercise

What is calorie creep?

Gradual increase in calorie intake after initial restriction that can halt weight loss

Name three ways to avoid calorie creep and break plateaus.

Monitor diet, vary exercise intensity/type, and watch for gradual return of old habits

What are benefits of regular physical activity for weight management?

Improves self-esteem, quality of life, bone health, maintains/increases lean mass, supports fat use

What is the physical-activity recommendation for weight management?

150–300 min/week moderate-intensity aerobic activity plus muscle-strengthening at least 2 days/week

What are key Dietary Guidelines to support healthy weight?

Limit added sugars and saturated fat to < 10% of calories, sodium < 2300 mg/day, limit alcohol to ≤ 2 drinks/day (males) or ≤ 1 drink/day (females)

What weight-loss goal is considered clinically meaningful?

Loss of 5%–10% of baseline weight over ≈ 6 months at 1–2 lb/week

What are SMART goals in weight management?

Specific, Measurable, Achievable, Relevant, Time-bound behavior-change goals

Give two examples of behavioral tactics to aid weight loss.

Plan meals/snacks ahead and eat slowly to avoid overeating

Name two strategies to reduce triggers for overeating.

Store food out of sight and eat only in designated dining areas

Give one holiday/party strategy to support weight management.

Eat a high-fiber snack beforehand and alternate water with alcoholic drinks

Name one portion-control tactic in restaurants.

Ask server to pack half the entrée to-go before it’s served

What percentage of baseline weight loss is often enough to yield major health benefits?

5%–10%

What characteristics define a sound weight-loss plan?

Balanced, flexible, socially supportive, promotes slow/steady loss, encourages physical activity, adapts to individual needs

List two red flags of a fad diet.

Promises rapid weight loss and severely restricts food choices

Name three top-ranked diets for weight management and health.

Mediterranean, DASH, and Flexitarian diets

Give one example of a weight-loss medication and its mechanism.

Orlistat (Xenical/Alli) – blocks fat absorption in intestine

Name one common side effect of Orlistat.

Gastrointestinal issues such as oily stools and diarrhea

Which weight-loss drug mimics a gut hormone to reduce appetite and increase satiety?

Liraglutide (Saxenda) or Semaglutide (Wegovy)

What are key eligibility criteria for bariatric surgery in adults?

BMI ≥ 40 or ≥ 35 with comorbidity, after failed diet/medication attempts

What is a very-low-calorie diet (VLCD) and when is it used?

< 800 kcal/day under strict medical supervision for severe obesity; causes ≈ 2–4 lb/week loss, mostly water/lean tissue

Name two common types of bariatric surgery.

Gastric bypass and sleeve gastrectomy

What BMI defines underweight and what are some causes?

BMI < 18.5; may be due to illness, excessive dieting, genetics, metabolic or satiety-signal irregularities

What is the general approach to healthy weight gain?

Combine a nutrient-dense diet (protein, healthy fats, complex carbs) with strength-training exercise