1. Body Composition Assessment
CHAPTER
OUTLINE
Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Chapter 4
Body Composition Assessment

2. Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Key Terms
Body composition: The fat and nonfat components of the human body; important in assessing recommended body weight
Percent body fat: Proportional amount of fat in the body based on the person’s total weight; includes both essential and storage fat
Lean body mass: Body weight without body fat
Recommended body weight: Body weight at which there seems to be no harm to human health (healthy weight)

3. Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Key Terms
Overweight: Excess body weight against a given standard such as height or recommended percent body fat; less than obese
Obesity: A chronic disease characterized by excessive body fat in relation to lean body mass; usually at least 30% above recommended body weight
Essential fat: Minimal amount of body fat needed for normal physiological functions; constitutes about 3% of total weight in men and 12% in women
Storage fat: Body fat in excess of essential fat; stored in adipose tissue

4. Typical Body Composition of an Adult Man and Woman
4.1
Typical Body Composition of an Adult Man and Woman
Essential fat constitutes about 3% of the total weight in men and 12% in women

5. Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Critical Thinking
Jessica is a gymnast whose coach has asked her to decrease her total body fat to 7%. Can Jessica’s performance increase at this lower percent body fat?
How would you respond to this coach?

6. Assessing Body Composition
Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Assessing Body Composition
Research/medical facility techniques
Dual energy X-ray absorptiometry (DEXA)
Magnetic resonance imaging (MRI)
Computed tomography (CT)
Total body electrical conductivity (TOBEC)

7. Assessing Body Composition
Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Assessing Body Composition
More common techniques
Hydrostatic weighing
Air displacement
Skinfold thickness
Girth measurements
Bioelectrical impedance

8. DEXA Procedure is simple; takes only 15 minutes to administer
Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
DEXA
Procedure is simple; takes only 15 minutes to administer
Not readily available to most fitness participants
Dual energy X-ray absorptiometry (DEXA)
Frequently used by research and medical facilities
Considered by many as the standard technique for body composition assessment
Uses low-dose beams of X-ray energy
Measures fat mass, fat distribution pattern, and bone density

9. Hydrostatic Weighing Underwater weighing
Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Hydrostatic Weighing
Underwater weighing
Most common technique used for decades
A person’s “regular” weight is compared with underwater weight
Fat is more buoyant than lean tissue
Almost all other indirect techniques have been validated against hydrostatic weighing

10. Hydrostatic Weighing Drawbacks
Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Hydrostatic Weighing Drawbacks
Time consuming
Not feasible to test large number of people
Requires measurement of residual lung volume (if unknown, can be estimated)
Difficult to perform on the aquaphobic

11. Air Displacement Individual sits inside small chamber
Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Air Displacement
Individual sits inside small chamber
Computerized pressure sensors determine the amount of air displaced by the person
Body volume is calculated by subtracting the air volume with the person inside the chamber from the volume of the empty chamber (air in the lungs is taken into consideration)
Body density and percent body fat are then calculated
Less cumbersome to administer
Takes only about 5 minutes

12. Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Skinfold Thickness
Based on the principle that approximately half of the body’s fatty tissue is directly beneath skin
Reliable measurements of this tissue give a good indication of percent body fat
Skinfold test is done with pressure calipers
Several sites are measured and percent fat is estimated from the sum of the three sites using Tables 4.1 (women) and 4.2 or 4.3 (men)
All measurements should be taken on the right side of the body

13. Anatomical Landmarks for Skinfold Measurements
4.3
Chest
Abdomen
Suprailium
Triceps
Thigh

14. Skinfold Thickness Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Skinfold Thickness

15. Skinfold Technique: Percent Fat Estimates for Women
4.1

16. Skinfold Technique: Percent Fat Estimates for Men under 40
4.2

17. Girth Measurements Requires a standard measuring tape
Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Girth Measurements
Requires a standard measuring tape
Women: Upper arm, hip, and wrist measurements (cm)
Look up constants on Table 4.4 based on measurements and determine body density and percent fat according to predicting equations
Men: Waist and wrist measurements (inches)
Use Table 4.5 for percent body fat estimate

18. Girth Measurement: Conversion Constants to Calculate Body Density for Women
4.4

19. Girth Measurement: Estimated Percent Body Fat for Men
4.5

20. Bioelectrical Impedance
Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Bioelectrical Impedance
Simpler to administer, but accuracy is questionable
Sensors are applied to the skin and a weak electrical current is run through the body to estimate body fat, lean body mass, and body water
Based on the principle that fatty tissue is a less-efficient conductor of an electrical current
The easier the conductance, the leaner the individual
Body weight scales with special sensors on the surface may also be used to perform this procedure

21. Body Composition Classification according to Percent Body Fat
4.10

22. Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Body Mass Index (BMI)
Incorporates height and weight to estimate critical fat values at which disease risk increases
BMI = Body Weight (lbs) x 705 ÷ (height in inches)2
Example
Body Weight = 172 lbs Height = 67 inches
BMI = 172 x 705 ÷ (67)2
BMI = 27

23. Disease Risk according to BMI
4.7

24. Disease and Mortality Risk Based on BMI
4.6
Even though the risk for premature illness and death is greater for those who are overweight, the risk also increases for individuals who are underweight

25. Overweight and Obesity Trends in the United States
4.7

26. Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Waist Circumference
Predicts disease risk according to the way people store fat (waist versus other areas)
Disease Risk according to WC
4.8

27. Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Waist-to-Hip Ratio
Predicts disease risk according to “apple” or “pear” shape
Disease Risk according to Waist-to-Hip Ratio
4.9

28. Body Composition Changes for Adults in the U.S
15.8
Because of the typical reduction in physical activity, each year the average person gains 1.5 lbs of body fat and loses a half a pound of lean tissue

29. Recommended Body Weight Determination
Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Recommended Body Weight Determination
Determine pounds of body weight that are fat (FW): multiply body weight (BW) by current percent fat (%F) (FW = BW x %F)
Determine lean body mass (LBM): subtract weight in fat from total body weight (LBM = BW – FW)
Select a desired body fat percentage (DFP) based on health or high fitness standards given in Table 4.9
Compute recommended body weight (RBW) according to the formula RBW = LBM ÷ (1.0 – DFP)

30. Recommended Body Weight Determination: Example
Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Recommended Body Weight Determination: Example
Sex: female
Age: 19
BW: 160 lbs
%F: 30% (.30 in decimal form)
FW = BW x %F FW =160 x .30 = 48 lbs
LBM = BW – FW LBM =160 – 48 = 112 lbs
DFP: 22% (.22 in decimal form)
RBW = LBM ÷ (1.0 – DFP) RBW =112 ÷ (1.0 – .22) RBW =112 ÷ .78 = lbs

31. Essential and Storage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
Critical Thinking
How do you feel about your current body weight and what influence does society have on the way you perceive yourself in terms of your weight?
Do your body composition results make you feel any different about the way you see your current body weight and image?

32. Effects of a 6-Week Aerobics Exercise Program on Body Composition
4.9
Loss of lean body mass can be offset or eliminated by combining a sensible diet with physical exercise

33. End of Chapter