Chapter 8 Energy Balance and Body Composition

Bomb Calorimeter How Do We Know How Much Energy Comes From A Food? Calorimetric Values versus Physiological Fuel Values

Physiological Influences - empty stomach & gastric contractions - absent of nutrients & GI hormones - endorphins (brain’s pleasure compounds) Cognition Influences - presence of others (social occasions) - perception of hunger or time of day - abundance of food or free food Hunger Satiation Seek Food Continue Meal Ends Postingestive Influences - presence of food triggers stretch receptors - nutrient in intestine elicit hormones such as CCK Postabsorptive Influences - nutrients in blood signal brain - as nutrients diminish, satiety diminishes and hunger develops Satiety

Message Central Hypothalamus - involved in controlling water balance, regulation of body temperature and appetite control e.g. Leptin - protein hormone produced by adipose cells - acts on the hypothalamus - promotes negative energy balance by suppressing appetite & increasing energy metabolism

So we know where Energy Imput comes from but….. Where Does the Energy Go? Basal Metabolism: - energy to run activities such as: -- maintaining body temperature -- keeping autonomic systems (lungs, heart, kidneys, blood cells production, etc)

Factors That Affect BMR - Height - Age and Body Composition - Growth Rates - Fever - Stresses - Environmental temperature - Fasting / Starvation - Malnutrition - Nicotine and Caffeine - Sleep

©2001 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning ™ is a trademark used herein under license. BMR (Basal Metabolic Rate) BMR varies with body size and shape due to surface area

Factors That Affect BMR - Height - Age and Body Composition - Growth Rates - Fever - Stresses - Environmental temperature - Fasting / Starvation - Malnutrition - Nicotine and Caffeine - Sleep

So we know where Energy Imput comes from but….. Where Does the Energy Go? Physical Activity Thermic Effect of Food

BMI (The Body Mass Index)

BMI values Obese Over weight Healthy Under weight Pounds (without clothes) Height (without shoes)

Body Compositions Compared FatMuscleBoneOrgans % Body Mass

Healthy and Obese Body Compositions Compared % Body Mass FatMuscleBoneOrgans % Body Mass FatMuscleBoneOrgans WomenMen Healthy Obese Healthy Obese

% Body Mass Mortality Body Mass Index versus Mortality

Health Risks Associated with Body Weight and Body Fat Underweight - depends on the reason why an individual is underweight - individuals can be underweight and healthy - however, often underweight is due to malnutrition, smoking habits, or illness.

Health Risks Associated with Body Weight and Body Fat Overweight - diabetes, hypertension, cardiovascular disease and stroke, apnea, osteoarthritis, cancer, and complications during surgery or pregnancy.