Download Body Composition

Body Composition
Body Composition
• The amount of fat, and fat-free mass in the body
– Fat
– Fat-free mass
• Muscle
• Bone
• Body composition assessed in a variety of ways
– Advantages for each method
– Disadvantages for each method
• Cost, availability, complexity, user/equipment error,
quality/quantity of information, accuracy
Scale Weight
• Provides information on
amount body mass
• Advantages and
disadvantages
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Cost
Availability
Complexity
User/equipment error
Quality/quantity of
information
– Accuracy
Height and Weight Charts
• Provides information
based on person’s height,
weight, frame size
• Advantages &
Disadvantages
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Cost
Availability
Complexity
User/equipment error
Quality/quantity of
information
– Accuracy
Body Mass Index
• Person’s weight divided
by square of height
• Provides information on
disease risk
• Advantages &
Disadvantages
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Cost
Availability
Complexity
User/equipment error
Quality/quantity of
information
– Accuracy
Circumferences
• Specific areas on body are
measured with measuring
tape
• Advantages &
Disadvantages
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Cost
Availability
Complexity
User/equipment error
Quality/quantity of
information
– Accuracy
Waist to Hip Ratio
• Two circumferences: waist and hip
• Measures provide CV disease risk
information
– Men: 0.90-1.0+ = “high risk”
– Women: 0.75-0.85+ = “high risk”
Waist to Hip Ratio
• Abdominal fat related to
cardiovascular disease risk
• Advantages &
Disadvantages
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Cost
Availability
Complexity
User/equipment error
Quality/quantity of
information
– Accuracy
Near Infrared Interactance
• Method based on light
absorption, reflectance
• Probe is placed on body
part, typically biceps
• Probe emits infrared light,
passing through tissue,
reflected back into probe
– Fat absorbs more infrared
light than fat-free mass
– The more light absorbed,
the higher the fat mass
Near Infrared Interactance
• Advantages & Disadvantages
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Availability
Complexity
User/equipment error
Quality/quantity of information
Accuracy
Skinfolds
• Specific instruments,
“calipers” used to assess
amount of fat under skin
at specific sites on body
• Since approximately 50%
of body fat is located
under skin, predictions can
be made about total body
fat
Skinfolds
• Advantages & Disadvantages
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Availability
Complexity
User/equipment error
Quality/quantity of information
Accuracy
Bioelectrical Impedance Analysis
• A small, painless electrical
current passes through
body
• Based on current
difference between
starting and ending points,
percent fat can be
estimated
– Fat impedes/resists current
more than fat-free mass
– High impedance values will
reflect higher fat mass
Bioelectrical Impedance Analysis
• Advantages &
Disadvantages
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Cost
Availability
Complexity
User/equipment error
Quality/quantity of
information
– Accuracy
Hydrostatic Weighing
• Person weighed in regular
environment, and under
water
• Based on difference, can
eventually estimate body
volume
• From volume, one
calculates body density
• From body density, fat
percentage calculated
• Higher density = leaner
subject (bone, muscle are
denser than fat)
Hydrostatic Weighing
• Advantages & Disadvantages
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Complexity
User/equipment error
Quality/quantity of information
Accuracy
Air Displacement
• Similar to hydrostatic
weighing
• Device measures air
displacement to determine
body volume
• From volume one can
calculate body density
• From body density, fat
percentage is calculated
Air Displacement
• Advantages &
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Cost
Availability
Complexity
User/equipment error
Quality/quantity of
information
– Accuracy
Dual Energy X-Ray
Apsorptiometry (DEXA)
• Low-radiation dose of
dual-energy x-ray
beams pass over body
• Based on attenuation
of x-ray, measures of
fat, bone and soft lean
tissue can be made
• Based on these
measures, fat mass can
be calculated
DEXA
• Advantages & Disadvantages
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Cost
Availability
Complexity
User/equipment error
Quality/quantity of information
Accuracy
What is Average?
• Body Fat Ranges for Standard Adults
(NIH/WHO BMI Guidelines)
• Percent Body Fat Norms for Men and
Women (American Council on Exercise)