Body Composition

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Body Composition
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Body frame-size (BFS)

• Female
• 10.357Ht. (biacromial bitrochanteric)
• Male
• 8.239Ht. (biacromial bitrochanteric)

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Body frame-size (BFS)
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BFS Limitations

• Unvalidated estimates of body frame size
• Developed primarily from white population
• Focus on mortality data - not obesity related
  comorbidities
• No assessment of body composition

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BMI

• Body mass (kg) ? height (m2)
• optimal range 20 -25
• ? or ? from optimal range ? ? of disease
• CAD, HTN, CVA, DM, CA, etc.

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BMI

• Determine the BMI for
• Male
• weight 100 kg
• height 2 m

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BMI

• Limitations
• fails to consider composition of body
• fat

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BMI

• Generally related to body composition
• Highly correlated w/ relative body fat
• probably provides a better estimate of obesity

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BMI

• Overweight (1998)
• males ? 27.8 ? 25
• females ? 27.3 ? 25
• obese gt 30

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BMI
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BMI
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Population Overweight
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Population Overweight

• 1976-80
• 25 of all US adults ? 20
• 1988-91
• 33.4
• 47.2 Mexican-American women
• 48.6 African-American women

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Leanness in Women

• Active low weight women are at risk of
• delayed onset of menstruation
• irregular menstrual cycle (oligomenorrhea)
• cessation of menses (amenorrhea)

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Leanness in Women

• Hypotheses
• Exercise Stress (disruption of hypothalamic-pituit
  ary-adrenal)
• Energy Availability
• energy reserve inadequate to sustain pregnancy
• lt 17 cessation / 22 normal cycle

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Body Composition Models
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Body Composition

• Total Body-Fat (Fat-Mass) Essential Fat
  Storage Fat
• Essential Fat (survival)
• CNS
• Bone Marrow
• Organs (heart, liver, kidneys, spleen, etc.)

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Fat-Free Mass vs. LBM

• LBM includes essential fat
• LBM Body Mass - Storage Fat
• FFM excludes essential fat
• FFM Body Mass - Total Body Fat

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Behnke Model Males
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Behnke Model Females
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Body Composition

• 100 kg male w/ 20 body fat
• Body mass 100 kg
• Storage Body Fat 100 .20 20 kg
• Lean Body Mass 100 - 20 80 kg
• - includes 5 essential fat

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Body Composition

• Fat Free Mass Body Mass - Total Fat Mass
• Total Fat Mass 20 kg 4 kg (essential fats)
• Fat Free Mass 100 - 24 76 kg

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Importance of Body Fat
Diet
Exercise
Combination
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Importance of Body Fat
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Measuring Body Fat

• Direct
• chemical analysis
• dissection
• Indirect

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Measuring Body Fat

• Hydrostatic Weighing / Densitometry
• body volume loss of weight in H20 (scale wt. -
  underH2O wt)
• gold standard
• based on assumptions

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Measuring Body Fat

• Skinfolds/Fatfolds
• Girth Measurements
• Bioelectrical Impedance Analysis (BIA)
• conduction is better thru non-fat
• ? H20 ? ? impedance ? ? body fat

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Measuring Body Fat

• Near-Infrared Interactance (NIR)
• Futrex-5000
• fiber optic
• biceps of dominant arm
• validity????

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Measuring Body Fat

• US
• Arm X-Ray (3 site)
• CT scan
• MRI
• DEXA (Dual-energy X-Ray Absorptiometry)
• - bony mineral content
• - r 0.91 - 0.92

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Desirable Body Mass

• Males
• strive for 15
• lt 20
• Females
• strive for 25
• lt 30

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Desirable Body Mass

• 200 lbs. individual
• Wants to reduce body fat from 20 ? 10
• What is this individuals desirable weight?

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Desirable Body Mass

• Desirable Body Mass (DSB)
• fat-free body mass / (1.00 - desired fat)
• Current fat-free body mass
• 200 - (200 0.20)
• 160 lbs.

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Desirable Body Mass

• Desirable Body Mass (DSB)
• fat-free body mass / (1.00 - desired fat)
• DSB (160 / (1.00 - 0.10)
• 160 lbs. / .90
• 178 lbs.

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Desirable Body Mass

• What is the loss in body weight?
• 200 lbs. - 178 lbs. 22 lbs.

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General Guidelines for Weight Loss- Athlete

• lt 2 lbs./week --gt preserve FFM
• 200 - 500 kcal lt daily energy expenditure
• ? resistance and endurance training