Energy Balance and Body Composition

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Chapter 8

• Energy Balance and Body Composition

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How Do We Know How Much Energy Comes From A Food?
Bomb Calorimeter
Calorimetric Values versus Physiological Fuel
Values
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Physiological Influences - empty stomach
gastric contractions - absent of nutrients
GI hormones - endorphins (brains pleasure
compounds)
Hunger
Seek Food
Cognition Influences - presence of others
(social occasions) - perception of hunger
or time of day - abundance of food
or free food
Continue Meal
Satiation
Postingestive Influences - presence of food
triggers stretch receptors - nutrient in
intestine elicit hormones such as CCK
Meal Ends
Postabsorptive Influences - nutrients in blood
signal brain - as nutrients diminish, satiety
diminishes and hunger develops
Satiety
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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
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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)
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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
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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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So we know where Energy Imput comes from but..
Where Does the Energy Go?
Physical Activity
Thermic Effect of Food
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BMI (The Body Mass Index)
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18.5
25
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BMI values
Over weight
Under weight
Obese
Healthy
Height (without shoes)
Pounds (without clothes)
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Body Compositions Compared
Body Mass
Fat
Muscle
Bone
Organs
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Women
Men
Healthy
Healthy
Obese
Obese
Body Mass
Body Mass
Fat
Muscle
Bone
Organs
Fat
Muscle
Bone
Organs
Healthy and Obese Body Compositions Compared
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Body Mass Index versus Mortality
Mortality
Body Mass
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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.
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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.