Body composition is commonly referred to as body fat percentage. You'll find assessment tools like hand-held devices and scales for assessing body fat percentage at your local fitness facility. You're more likely to hear the term BMI (body mass index) at your doctor's office. BMI is easily calculated with measurements of height and weight. Both terms refer to body fat, but they are different.
The Facts
Body composition is a term used to describe the percentage of lean mass to fat mass that contributes to an individual's total body weight. Health and fitness professionals use different tools to assess body composition.
Body mass index is a weight-for-height ratio used to estimate body fat. BMI is calculated by dividing weight in kilograms by height in meters squared. According to the CDC, BMI is not a direct measure of body composition, but it correlates to the body's fatness.
Disease Risk
Higher BMIs and body composition percentages are associated with being overweight or obese. According to the Texas Heart Institute, carrying extra weight is thought to increase total cholesterol, blood pressure and increase the risk of developing coronary artery disease. Researchers also found that obese and overweight individuals are less likely to exercise, and therefore are more likely to suffer a heart attack when compared to individuals that participate in regular exercise.
Measurement
BMI is calculated by dividing weight in kilograms by height in meters squared. An easier conversion is weight in pounds divided by height in inches squared multiplied by 704.5. Standard ratios exist for men and women to determine body fatness based on height and weight ratios.
Body composition is determined by various assessments. Healthcare and fitness professionals use underwater weighing, bio-electrical impedance analysis and skin fold assessment to determine body composition. Body composition values are different for men and women and individuals are put in percentile categories based on body composition instead of categories of obesity.
Warning
Individuals with BMIs that fall into the overweight and obese categories, and individuals with higher percentages of body composition, are at increased risk of certain diseases and health conditions. The list of diseases and conditions include hypertension, hyperlipidemia, type 2 diabetes, stroke, osteoarthritis, gallbladder disease, coronary heart disease and cancer, to name a few.
Considerations
Though BMI is used to assess disease risk, it is not a good indicator of body fat percentage. Individuals with increased musculature and skeletal mass may be classified as obese, even though they are not. Anyone can assess BMI as long as height and weight measurements are available.
Assessing body composition is the best way to determine body fat percentage. The most widely used assessment tool available to determine body composition is skinfold measurement. The most accurate tools available to assess body composition are DEXA technology followed by underwater weighing. Some universities and research facilities have DEXA machines and underwater weighing equipment.
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