Chapter 6 Body Comp

7/29/2019 Chapter 6 Body Comp

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Body Composition

Forrest Dolgener, Ph.D.


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Body Composition Definitions

% Fat - percentage of total body weight that

is fat weight

Fat Weight - the weight of all the fat in the

body

Fat-Free Weight - the weight of everthing

that is not fat

Ideal Weight - the body weight at the

ideal % fat


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Body Weight = Fat Weight + Fat-Free Weight


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Computational Example

Weight = 200 lbs; % fat = 20%;

Fat Weight = 200 x .20 = 40 lbs Fat-Free Weight = 200 - 40 = 160 lbs


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Computing Ideal Weight

Ideal Weight = FFW / Ideal % FFW

Example

Body Wt = 180; %fat = 20%; What is ideal

body weight at 10% fat?

FW = 180 lbs x .20 = 36 lbs

FFW = 180 - 36 = 144 lbs

IBW = 144 / .90 = 160 lbs


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Components of Fat-Free Weight

Muscle

Bone

Organ Systems


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Components of Fat Weight

Essential Fat

most is non-visibleassociated with deeper body structures

Non-essential or Storage FatBeneath the skin and visible

Adipose tissue fat


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Gender Differences

Females are absolutely fatter than males

Female sex hormones promote fat deposition

Male sex hormones promote muscle growth

Most of the females increase in fatness is

due to an increase in the essential fat stores

Males and females have similar levels of

non-essential fat


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Gender Differences in Body Composition

Males Females

Body Weight 150 115

Total Fat 15% (22.5 lb) 25% (28.8 lb)

Essential Fat 3% (4.5 lb) 12% (13.8 lb)

Storage Fat 12% (18 lb) 13% (15 lb)


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15-18% 8-10%


11/254-6% 4-6%


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Methods of Determining

Body Compostion Body Mass Index

Underwater Weighing (Hydrodensitometry)

Skinfolds

Bioelectric Impedance

Infrared Interactance


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Body Mass Index

BMI = (704.4 X weight)/(height in inches)2

A BMI between 16-25 is considered healthy

As BMI > 25, health risk increases


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Problems With BMI

Weight = 280 lbs

Height = 77 inches

%fat = 30% (obese)

BMI = 33 (obese)

Weight = 280 lbs

Height = 77 inches

%fat = 15% (healthy)

BMI = 33 (obese)


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Interpreting % Fat Values

All methods of measuring % fat have a

certain amount of inaccuracy! This

inaccuracy is determined by the StandardError of Estimate (SEE).

The SEE tells you the amount of deviation

from the true % fat you can expect from aparticular method.


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There is a 67% probability that the true %

fat is within + or - one SEE from themeasured value.

Example: Measure % fat = 20%;

SEE = 3 % units of body fat

There is a 67% probability that the

true % fat is between + or - one SEEor 3 % units of fat. or between 17 -

23 %.


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There is a 95% probability that the true %

fat is withing + or - two SEE from the

measured value.

Example: Measured %fat = 20%

SEE = 3 %There is a 95% probability that the

true %fat is within + or - two SEE or

6% of the measured value or 14 - 26%.


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SEE of Common Methods

Skinfolds - 3%

Bioelectric Impedance - 3%

Infrared Interactance - 5%


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Healthy Values for %Fat

Reasonable & Healthy %fat Range

Males: 10 - 20%

Females: 15 - 30%

Chapter 6 Body Comp

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