NHM 101 Lecture 9: Ch 8 - Energy Balance and Body Composition
2 May 2018
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Chapter 8- Energy Balance and Body Composition
Energy Balance
Intake: Calories from foods
Output: Calories used to maintain body functions and physical activity
Weight Fluctuations
Quick weight gain or loss
Slow weight gain or loss
- Some fat
- Some lean tissues
- MOSTLY fluids
- 75% fat
- 25% lean
Energy Intake
Bomb Calorimeter- how the calories in food is determined
- constant-volume calorimeter used in measuring the heat of combustion of a
particular reaction
How can we determine our individual caloric intake?
- Calculations
- Food records
- Exchange Lists- a grouping of foods in which the carbohydrates, fats, proteins,
and calories are similar for the serving sizes listed
- Dietary analysis programs (e.g. phone apps)
Energy Expenditure
Total Energy Expenditure includes:
● Basal Metabolism (BMR) Energy burned for life-sustaining activities
age
height
rate of growth
gender
body composition
fever
stress
environ. temp
fasting/starving
hormones
smoking
caffeine
sleep
● Physical activity
○ This piece is the most variable
● Thermic Effect of Food (TEF) The amount of energy expenditure above the
resting metabolic rate due to the cost of processing food for use and storage
find more resources at oneclass.com
find more resources at oneclass.com
Why is BMR higher in
infants
than in
adults
?
- The intensity of body functions is much higher in infants
- The rate of growth is much higher and needs more energy to support that
Estimating Energy Expenditure:
● Estimated Energy Requirements- average dietary energy intake that is predicted
to maintain energy balance in healthy, normal weight individuals of a defined age,
gender, weight, height, and level of physical activity consistent with good health
● Harris Benedict Equation- used to estimate an individual's BMR
● Mifflin St. Jeor Equation- used to estimate an individual's BMR
○ *tk + .*Htm ‐ *(ers + = restin ener ependiture
■ (male)
○ *tk + .*Htm ‐ *(ers ‐ = restin ener ependiture
■ (female)
● Determine your own calorie intake
○ Indirect Calorimetry
■ measures respiratory gas exchange from which energy expenditure
can be estimated. Oxygen consumption (VO2) and carbon dioxide
(CO2) production occur during the oxidation of carbohydrate, protein,
and fat. Heat production can be calculated from a measurement of
VO2 consumption or CO2 elimination.
○ Direct Calorimetry
■ measurement of the amount of heat produced by a food item enclosed
within a small chamber
○ Accelerometry
■ uses activity monitors and pedometers to estimate physical activity
Body Weight & Composition
Body Composition: Proportion of muscle, bone, fat, and other tissues that are total weight
- Impossible to directly measure body composition in a living human
- Weight changes alone may NOT be a good picture of body composition changes
Measuring Body Composition:
● Skinfold Measures:
find more resources at oneclass.com
find more resources at oneclass.com
