According to the CDC, calculating body mass index (BMI) is one of the best methods for population assessment of overweight and obesity. BMI is calculated from your weight and height (weight(kg)/[height(m)]2). Despite the positive aspects of BMI measurements, there are also some drawbacks. BMI does not distinguish between fat mass and lean mass, rather your entire mass is measured as a whole. The only way to differentiate between the two masses is to undergo a body composition assessment. Skinfold measurements are the cheapest, easiest way to get reasonably accurate results.
Step 1
Visit a personal trainer or other trained professional to have a skinfold assessment performed. The professional will calculate your measurements and provide you with a body fat percentage.
Step 2
Use your body fat percentage to calculate your lean mass percentage. For example, if you have a body fat percentage of 15, then you will have a lean mass percentage of 85.
Step 3
Convert your lean mass percentage to actual fat-free weight. For example, if you weigh 70 kilograms (154 lbs) and have a lean mass percentage of 85, then your lean mass weight is 59.5 kilograms (130.9 lbs).
Step 4
Compare your lean mass weight to your BMI. You may find that your BMI assessment falsely placed you in an unhealthy category. A 5-foot-5-inch female weighing 154 lbs. would have a BMI of 25.7, which would place her in the overweight category. However, according to her body composition, the majority of her weight is lean mass, which poses no health risk.
Tips and Warnings
- Lean mass is made up of muscle, bone, connective tissue and organs. There is no true way to establish the weight of muscle alone. There are do-it-yourself monitors and scales on the market that will measure your body fat percentage if you are uncomfortable going to a professional. Keep in mind, however, that these methods are less accurate.
Things You'll Need
- Body composition assessment
- Calculator
References
- ACSM's Guidelines for Exercise Testing and Prescription", Seventh Edition; Lawrence Armstrong, PhD, FACSM, Gary J. Balady, MD, Michael J. Berry, PhD, FACSM, Shala E. Davis, PhD, FACSM, Brenda M. Davy, PhD, RD, LC, Kevin P. Davy, PhD, FACSM, et al; 2006
- CDC: Healthy Weight, BMI
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