Body Fat Measurement

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Body Fat Measurement
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Basics

• With all body composition measurements you want
  to make sure it is done correctly by a qualified
  professional.
• When it comes to measuring body fat
• No method is 100 percent accurate, all forms of
  measurements have potential inaccuracies.
• Use the number as a starting point

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Common Methods

• Underwater weighing (hydrostatic) - considered
  the most accurate method.
• BodPod - similar to underwater weighing, except
  it uses air displacement.
• Skinfold calipers (pinchers)
• Convenient and good for use in a field setting
• Relatively accurate
• invasive
• Bioelectric impedance analysis (BIA)-
• Non invasive
• special scales and hand-held instruments
• relatively accurate if you are hydrated
  appropriately.

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Underwater Weighing(Hydrostatic)

• Subject exhales all the air while submerged in a
  tank of water.
• Does not measure body fat - measures body
  density, which translates mathematically into
  percent fat.
• Errors can happen with an inexperience person
  being weighed.
• Two cups (a half liter) of air can affect
  body-fat measurements by as much as 3 to 5
  percent.

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Bod Pod

• The Bod Pod takes air-pressure measurements that
  determine body volume from air displacement.
• These measurements are then translated into
  percent body fat, using a principle similar to
  underwater weighing.
• Comfortable and easy
• Less stressful than the underwater weighing
• Accuracy is similar to that of underwater
  weighing-within 1 percent.

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Skinfold Calipers

• Skinfold calipers measure the thickness of the
  fat layer on specific body sites.
• Measurements an inch above or below the
  established pinch point can add 5 - 15
  millimeters to the measurement
• Individual fat patterns also contribute to
  inaccurate calculations.
• The measurements from lean athletes should be
  plugged into sport-specific conversion equations.

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Skinfold Calipers

• It is prudent to record skinfold measurements on
  a monthly basis of people losing a significant
  amount of weight.
• Comparing the numbers can help dieters monitor
  changes.
• This use of calipers does not give a 100
  accurate picture -but it shows trends.
• Well trained health professionals are the most
  qualified to us this method
• Use the same technician to measure the client
  each time
• Use the same calipers
• Use the same conversion equations

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Bioelectrical Impedance

• Bioelectrical impedance sends an imperceptible
  electrical current through the body.
• Water in the body affects the opposition to the
  flow of the current (impedance).
• Water is only in fat-free tissue
• the current can be translated into percent body
  fat
• Some models assess regional body composition
• Leg to leg (Tanita scale)
• Hand-held Omron model (arm to arm)

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Disadvantages to Skinfold Calipers

• The body fat of lean athletes is sometimes
  overestimated and the fatness of overweight
  people is sometimes underestimated.
• If you measure after you exercise, youll likely
  have a lower percentage of fat compared with the
  preexercise measurement because hydration affects
  the measurement.
• Other factors that may affect the accuracy of the
  measurement include
• ethnic background
• premenstrual bloat
• food in the stomach
• carbo-loaded muscles