Chapter 8
Energy Balance and Body Composition
How Do We Know How Much Energy
Comes From A Food?
Bomb
Calorimeter
Calorimetric Values
versus
Physiological Fuel
Values
Physiological Influences
Hunger
Seek
Food
Continue
Meal
Satiation
- 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
Postingestive Influences
- presence of food triggers stretch receptors
- nutrient in intestine elicit hormones such as CCK
Meal
Ends
Postabsorptive Influences
Satiety
- nutrients in blood signal brain
- as nutrients diminish, satiety diminishes and
hunger develops
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
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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)
Weight (kg)
BMI =
[Height (m)]^2
18.5
25
30
Healthy
Over
weight
Obese
Height (without shoes)
BMI values
Under
weight
Pounds (without clothes)
% Body Mass
Body Compositions Compared
Fat
Muscle
Bone
Organs
Women
Men
Healthy
Obese
% Body Mass
% Body Mass
Healthy
Obese
Fat
Muscle
Bone
Organs
Fat
Muscle
Bone
Organs
Healthy and Obese Body Compositions Compared
versus
Mortality
Body Mass Index
% Body Mass
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.