Energy Balance

1
Chapter 8

• Energy Balance
• and
• Body Composition

2
I. Energy Balance (kcal)

• A. Body Energy Energy In - Energy Out
• 1. Energy in energy out 8 body energy
• a. 8 body energy 8 body fat (weight)
• b. 3500 kcals 1 lb body fat
• 2. Energy in
• a. 9 body energy 9 body weight

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Energy Balance
4
Weight loss (cont)

• b. weight loss - Rule of 10 (10 kcals/lb
  weight)
  
• 1. Example
• Female, 160 lbs., 5' 4", 19 y/o
• A caloric intake of 1600 kcal should result
  in weight loss (Caloric requirement is
  actually 2350 kcal see pg. 241)
  
• 3. Recommended weight loss is 1 lb/week

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Weight loss (cont)

• B. Quick weight loss does not mean loss of fat
• 1. Lean body tissue
• a. Contains water
• 2. Weight loss includes lean body tissue and
  water

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II. Energy In Food Calories

• A. Food Composition
• 1. Energy yielding macronutrients (CHO,
  protein, fat)
  
• a. Bomb calorimeter
• 1. Direct measurement
• 2. burn a food and measure heat
  production
  

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Bomb Calorimeter
8
Energy yielding macronutrients (cont) (CHO,
protein, fat)

• b. Mathematic correction
• 1. Corrects for inefficiency in human
  metabolism
  
• a. CHO 4 kcals/gram
• b. Protein 4 kcals/gram
• c. Fat 9 kcals/gram
• d. Alcohol 7 kcals/gram
• 2. Values slightly lower than that derived
  from the bomb calorimeter

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Energy In Food Calories (cont)

• B. Determinants of Food Intake
• conscious and unconscious factors involved
• 1. Control
• a. Hunger
• 1. Physiological stimuli
• a. Absence of food in GI system
• b. Hormonal signals (GI hormones,
  insulin)
  
• 2. Empty stomach
• a. Pressure change sends signal to
  brain

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Energy In Food Calories (cont)

• b. Appetite
• 1. Psychological stimuli
• a. Eating food when not hungry
• b. Not eating food when hungry
• c. Satiety
• 1. Physiological stimuli
• a. Presence of food in the stomach
• 2. Full stomach
• a. Pressure change sends signal to
  brain

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III. Energy Out Calories the Body Expends

• A. Generation of heat (thermogenesis)
• 1. 50 of energy derived from food is
  released as heat
  
• 2. 50 of energy from food captured in the
  form of ATP
  
• a. 50 of energy derived from ATP is
  released as heat
  

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Generation of heat (thermogenesis) (cont)

• 3. Overall 75 of energy derived from food is
  released as heat
  
• a. Maintenance of body temperature

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Energy Out Calories the Body Expends(cont)

• B. Measuring Energy Out
• 1. Direct
• a. Measure body heat
• 1. Expensive
• 2. Indirect
• a. Measure oxygen consumption
• 1. Metabolic cart
• a. Measures the amount of oxygen
  into the body and the output,
  difference is indicative of energy
  expenditure

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BMR and Surface Area
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Energy Out Calories the Body Expends(cont)

• C. Components of Energy Expenditure
• 1. Basal Metabolic Rate (BMR)
• basal thermogenesis
• a. 2/3 of total energy used by the body
• b. varies among individuals
• 1. tall, thin people 8 BMR
• c. increased BMR (life circumstances)
• 1. growing children
• 2. Pregnancy
• 3. stress

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Basal Metabolic Rate (BMR) (cont)

• 4. Overactive thyroid gland
  (hyperthyroidism)
  
• a. Thyroxine (T4), triiodothyronine (T3)
• 5. Extreme environmental temperatures
• 6. lean tissue mass
• a. 8 muscle mass
• d. decreased BMR
• 1. old age
• 2. loss of lean tissue mass
• 3. fasting/starvation
• 4. Malnutrition
• 5. underactive thyroid gland (hypothyroidism)

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Components of Energy Expenditure (cont)

• 2. Activity
• exercise-induced thermogenesis
• a. Most variable factor (table 8-2)
• 1. depends on body weight
• 2. depends on intensity of activity
• 3. depends on kind of activity

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Components of Energy Expenditure (cont)

• 3. Thermic effect of food
• diet-induced thermogenesis
• a. Not usually included in energy
  determination
  
• b. 10 of energy expenditure
• c. Energy required to eat
• 1. chewing food
• 2. digesting food
• 3. absorbing nutrients
• 4. transporting nutrients
• 5. storing excess nutrients
• 6. excreting waste

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Components of Energy Expenditure (cont)

• 4. Adaptation
• adaptive thermogenesis
• a. Not included in energy determination
• b. Energy required during adaptation to a
  situation
  
• 1. Stress
• 2. Temperature extreme
• 3. Injury

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Components of Energy Expenditure
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Components of Energy Expenditure (cont)

• C. Estimating Energy Requirements
• 1. Basal metabolism
• a. body weight (kg) x estimated kcals/kg/day
• b. Table 8-3 and pg. 239
• c. Example 110 lb., Female, 19 y/o
• 110 lbs. 50 kg Factor 14.7
• 49650 x 14.7 496
• 1231 kcal/day
• or
• 1 kcal (50 kg) (24 hrs.) 1200 kcal/day

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Estimating Energy Requirements (cont)

• 2. Voluntary activity
• a. use daily activity factor (table 8-4)
• b. Example female, moderate activity
• BMR 1231, Activity Factor 1.6
• Activity factor (x BMR) 1.6 x 1231
• 1970 kcal
• 3. Quick calculation for Daily Energy with
  Activity Factored
  
• a. Example 50 kg (38 kcal/kg/day) 1900
  kcal

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IV. Body Weight and Body Composition

• A. Body weight
• 1. body weight fat lean tissue water
• 2. Ideal Body Weight (IBW)
• a. Table 8-5 (criticized for not separating
  sexes)
  
• 1. Weight/height
• 2. Considerations
• a. (Sex), frame size and age
  dependent
  
• 3. based on insurance data

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Ideal Body Weight (IBW) (cont)

• b. Example calculate IBW
• Height 5'2", weight 110 lbs., female, 19 y/o,
  medium frame size
  
• IBW Weight/Ideal Weight x 100
• 110/120 92 IBW
• c. Quick calculation for IBW
• Female 100 lbs. 5' plus 5 lbs. for each
  inch over
  
• Height 5'2", so IBW 100 (2 x 5) 110
  lbs.
  
• d. Utility is debatable

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Body Weight (cont)

• 3. Body weight and standards
• a. 10-20 IBW overweight
• b. 8 20 IBW obese
• c. 10 9 IBW underweight
• B. Body Mass Index (BMI)
• 1. Weight relative to height
• 2. Weight in kg/height in M2
• a. Example 110 lbs., 5'2"(110/2.2) 50 kg
• (62" x 2.54) 157.5 cm or 1.58 M, 1.582
  2.5 BMI 50 / 2.5, BMI 20

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Body Mass Index
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Body Mass Index (BMI) (cont)

• b. Height doesnt change much in a adulthood
  so as weight increases BMI increases
  
• 3. 8 BMI associated with 8 in disease
• C. Body Fat and Its Distribution
• 1. Body fat percentage
• a. Male 10-25
• b. Female 18-32
• 2. No single criteria for Optimal Health
• a. Some people may have a little more some
  less
  
• b. individual's health important
• c. increased obesity leads to decreased
  exercise

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Body Fat and Its Distribution (cont)

• 3. Fat distribution
• a. Central obesity (android obesity)
• 1. Fat accumulation around the abdomen
  (apple)
  
• 2. Associated with increase in disease
• 3. Associated with men
• b. Lower body fat (gynoid obesity)
• 1. Fat accumulation around the hips (pear)
• 2. Not associated with increase in disease
• 3. Associated with women

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Android Obesity
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Body Fat and Its Distribution (cont)

• 4. Measurement of fat
• a. fatfold measurements
• 1. Uses calipers to measure subcutaneous
  fat
  
• 2. Measures subscapular and triceps fat
• 3. good estimate of body fat (5)
• 4. easy to use
• b. waist to hip ratio
• 1. fat location

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Triceps Skinfold
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Waist to Hip Ratio
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Measurement of fat (cont)

• c. other measurements
• 1. underwater weighing
• 2. total body water determination
• 3. magnetic resonance imaging
• 4. bioimpedance

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V. Health Risks Associated with Body Weight and
Fat

• A. Underweight
• 1. Further compromises status during
  disease
  
• a. Particular problem in wasting diseases
  such as cancer, and AIDS
  
• 2. Changes in physiology
• a. Women cease menstruating when body fat 12

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Health Risks Associated with Body Weight and Fat
(cont)

• B. Overweight
• 1. Coronary heart disease 8
• a. Especially with central obesity
• 2. Diabetes
• a. Non-insulin dependent diabetes 3x 8
• 3. Cancer
• a. Obesity is associated with various
  cancers
  
• 1. Breast
• 2. Colon
• 4. Hypertension (high blood pressure)

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Health Risks Associated with Body Weight and Fat
(cont)

• C. BMI and disease
• 1. Figure 8-5

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BMI and Mortality
38
Hunger
39
Appetite