Body Composition Assessment

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Chapter 4
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• Body Composition Assessment

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Key Terms
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• 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 persons 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)

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Key Terms
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• 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

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Typical Body Composition of an Adult Man and Woman
4.1

• Essential fat constitutes about 3 of the total
  weight in men and 12 in women

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Critical Thinking
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• Jessica is a gymnast whose coach has asked her to
  decrease her total body fat to 7. Can Jessicas
  performance increase at this lower percent body
  fat?
• How would you respond to this coach?

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Assessing Body Composition
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• Research/medical facility techniques
• Dual energy X-ray absorptiometry (DEXA)
• Magnetic resonance imaging (MRI)
• Computed tomography (CT)
• Total body electrical conductivity (TOBEC)

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Assessing Body Composition
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• More common techniques
• Hydrostatic weighing
• Air displacement
• Skinfold thickness
• Girth measurements
• Bioelectrical impedance

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DEXA
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• 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

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Hydrostatic Weighing
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• Underwater weighing
• Most common technique used for decades
• A persons 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

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Hydrostatic Weighing Drawbacks
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• 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

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Air Displacement
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• 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

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Skinfold Thickness
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• Based on the principle that approximately half of
  the bodys 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

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Anatomical Landmarks for Skinfold Measurements
4.3
Chest
Abdomen
Suprailium
Triceps
Thigh
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Skinfold Thickness
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight
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Skinfold Technique Percent Fat Estimates for
Women
4.1
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Skinfold Technique Percent Fat Estimates for Men
under 40
4.2
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Girth Measurements
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• 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

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Girth Measurement Conversion Constants to
Calculate Body Density for Women
4.4
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Girth Measurement Estimated Percent Body Fat for
Men
4.5
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Bioelectrical Impedance
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• 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

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Body Composition Classification according to
Percent Body Fat
4.10
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Body Mass Index (BMI)
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• 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

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Disease Risk according to BMI
4.7
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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

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Overweight and Obesity Trends inthe United States
4.7
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Waist Circumference
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• Predicts disease risk according to the way people
  store fat (waist versus other areas)

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Waist-to-Hip Ratio
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• Predicts disease risk according to apple or
  pear shape

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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

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Recommended Body Weight Determination
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• 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 formulaRBW LBM (1.0 DFP)

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Recommended Body Weight Determination Example
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• Sex female
• Age 19
• BW 160 lbs
• F 30 (.30 in decimal form)

• FW BW x FFW 160 x .30 48 lbs
• LBM BW FWLBM 160 48 112 lbs
• DFP 22 (.22 in decimal form)
• RBW LBM (1.0 DFP)RBW 112 (1.0
  .22)RBW 112 .78 143.6 lbs

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Critical Thinking
Essential andStorage Fat
Techniques to Assess Body Composition
Determining Recommended Body Weight

• 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?

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Effects of a 6-Week AerobicsExercise Program on
Body Composition
4.9

• Loss of lean body mass can be offset or
  eliminated by combining a sensible diet with
  physical exercise

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End of Chapter