Measuring body composition or “body fat percentage” estimates the proportion of fat to fat-free mass--muscles, bones, etc.—in a person’s body. The recommended body fat level for men is lower than that of women because of physiological differences between the sexes, leading to proportionally more muscle and less fat in men.
Methods
The most accurate methods for estimating body fat measure the amount of water or air that a person’s body displaces through hydrodensiometry and plethysmography, respectively. However, these methods are expensive and require specialized equipment. More commonly, trained professionals estimate body fat by taking skinfold measurements at a man’s tricep, chest, and thigh or below his shoulder blade. According to the American College of Sports Medicine, or ACSM, skinfold measurements are accurate to within 3.5 percent when done properly. Bioelectrical impedance, in which a device measures how easily an imperceptible electric current passes through the body, can be as accurate as skinfold measurements and are less intrusive.
Benefits
Having too much fat raises a man’s risk for several chronic diseases including cardiovascular disease, diabetes, high blood pressure and some cancers. Body fat used to be estimated based on a person’s ratio of height to weight, or body mass index. However, BMI tables overestimate fat in muscular men. Body composition measurements, which distinguish between fat and lean mass help exercise and medical professionals better determine an individual’s ideal body weight, and establish whether weight changes are from fat or muscle loss or gain.
Considerations
Each method for measuring body fat has a margin of error. In body density measurements—hydrodensiometry and plethysmography—the amount of air in the subject’s lungs affects the test’s accuracy. Skinfold measurements’ accuracy depends on the technician’s skill. Skinfold measurements also assume a standard ratio of subcutaneous—below-the-skin—fat to total body fat, but this ratio actually varies by age and ethnicity. Bioelectrical impedance tests assume that the subject is properly hydrated. Additionally, all calculations assume a standard density for muscles, bones and fat, which may actually vary by individual.
Evaluation
ACSM recommends that men maintain a body fat percentage between 10 and 22 percent. African American and Caucasian men under 40 with a body fat percentage of 20 percent, and men over 60 with over 25 percent fat have an elevated risk of health problems. Young men with a body fat percentage over 25 percent, and older men with over 30 percent have a high disease risk. Men who fall below the recommended range—8 percent for young men and 13 percent for older men—also risk health complications.
Ideal Weight
To determine your ideal weight, subtract your body fat percentage from 100 to determine your percentage of lean body mass, then divide that number by 100 to convert it to a decimal. Multiply your percentage of fat free mass by your weight to calculate your lean body mass in pounds. Use that value in the following ACSM equation to determine your ideal body weight:
Lean Body Mass ÷ [1 – (Desired % Fat ÷ 100)] = Ideal Weight
References
- "ACSM's Guidelines for Exercise Testing and Prescription: Eighth Edition"; American College of Sports Medicine; 2010
- "ACSM's Resources for the Personal Trainer: Second Edition"; American College of Sports Medicine; 2007
- "Personal Trainer Manual: The Resource for Fitness Instructors"; American Council on Exercise; 1991
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