Nutrition Chapter on Energy Balance

Study Notes

Excess energy is stored as fat.
Fat is used for energy between meals.
Energy balance is when energy in equals energy out.
A change in balance causes changes in weight, impacting fat, fluid, and muscle tissue.
One pound of fat equals 3500 excess kcalories.

Bomb calorimeters measure a food's energy value by measuring the amount of oxygen consumed.
Oxygen consumption is an indirect measure of released energy.
Energy is calculated from carbohydrates, fat, and protein in foods.

Hunger is a physiological response to nerve signals and chemical messengers from the hypothalamus.
Satiety is the feeling of fullness, signaling to stop eating.
Satiation is the feeling of fullness, signaling to stop eating.
Stress eating and external cues like time of day, food availability, and taste, can override hunger and satiety.
Nutrient composition (protein, low-energy density foods, and high-fiber foods) influences satiation/satiety. High-fat foods are strong satiety signals.

Thermogenesis is the generation of heat.
Thermogenesis categories: basal metabolism, physical activity, and food consumption.

Basal metabolism is about two-thirds of daily energy expenditure.
Basal metabolic rate (BMR) varies among and within individuals throughout the day.
Lean tissue is more metabolically active than fat tissue.
Resting metabolic rate (RMR) is also a measure of energy expenditure. (Factors influencing BMR include age, growth, gender, stresses, environmental temperature, fasting, malnutrition, hormones (gender), smoking, caffeine, and sleep).

Physical activity is voluntary skeletal muscle movement.
It's the most variable component of energy expenditure.
Factors influencing energy expenditure include muscle mass, body weight, and activity frequency, intensity, and duration.

The thermic effect of food is the acceleration of gastrointestinal (GI) activity in response to food presence.
This releases heat, and is approximately 10% of energy intake.
It's greater for high-protein foods compared to high-fat foods.

Factors influencing BMR include gender, growth, age, and physical activity, body composition, and height and weight.
BMR declines during adulthood.

Defining healthy body weight is subjective, often based on perceived image versus actual body size and "ideal" standards, rarely corresponding with health.

Information on body fat percentage and distribution is important for disease risk.
The ideal amount of body fat varies per individual, with common values noted for athletes.
Central (visceral) obesity, fat stored around the abdomen, may be a stronger risk factor than subcutaneous fat.
Waist circumference is a good indicator of central obesity.
Ranges for body fat percentage are included by gender.

Body weight and fat correlate with disease risk and life expectancy but are not the direct cause.
Risks associated with underweight include fighting wasting diseases, menstrual irregularities, and infertility, osteoporosis, and bone fractures.
Risks associated with overweight/obesity include obesity as a designated disease, health risks (cardiovascular disease, diabetes (type 2), inflammation, metabolic syndrome, and cancer), disability, costs (lost work and shortened life expentancy).

Cardio-respiratory and muscular fitness play a vital role in health and longevity.
Fitness offers many health benefits independent of body weight and is vital.