Medical and fitness personnel often use body weight to compare individuals to norms based on the general population. But if you have an athletic build, chances are you're toward the higher end of the charts. You might look like an Adonis or Aphrodite, but your greater lean muscle mass and bone density could get you categorized as overweight or obese based on weight alone. Body composition is the best way to calculate your ideal weight for an athletic build.
Of the many methods used to evaluate ideal weight, one of the most common is body mass index, or BMI. You calculate BMI by dividing your weight in kilograms by your height in meters squared. But Belgian social scientist Adolphe Quetelet devised the equation for BMI almost two centuries ago by collecting and comparing statistics on proportions of the human body. According to the Harvard School of Public Health, BMI does not directly assess body fat, and athletic people who have denser bones and muscles often have a high BMI.
Since bone and muscle are denser than fat, they weigh more by volume. Some body fat is necessary for health, with minimal levels of 3 percent for men and 12 percent for women considered essential. Beyond that, humans store fat in adipose tissue for energy reserves. Physical exercise tends to reduce excess body fat while increasing bone mineral density and lean muscle tissue, resulting in higher body weight for athletic people. If you are physically active, the most accurate way to determine your ideal weight is to estimate your current body fat percentage and then calculate how much fat you need to lose or gain to obtain optimal values.
Dunk or Pinch
While there are a number of methods and devices to calculate body fat percentage, hydrostatic weighing is considered the gold standard. The procedure involves sitting on a specialized scale and being fully submerged in a tank or pool. Because fat floats and muscle and bone tend to sink, your hydrostatic weight relative to your land weight gives a good picture of your percentage of body fat. However, the procedure is inconvenient to access and requires getting wet. The best alternative, according to exercise scientist Len Kravitz of the University of New Mexico, is the skinfold method, which involves measuring the thickness of subcutaneous fat. It's inexpensive and relatively noninvasive, but a trained fitness professional should perform the assessment.
Finding Your Best Weight
Optimal percentage of body fat ranges from 5 percent to 13 percent for men and 12 percent to 22 percent for women. Once you determine your current body fat percentage, you can mathematically project your ideal body weight. Subtract your current percent of body fat from 100 to get your current percent of lean weight and multiply it by your total body weight to get your current lean weight (CLW); subtract your desired body fat percent from 100 to get your desired lean weight percent (DL%); divide your current lean weight by your desired lean percentage to get your ideal body weight. The equation looks like this: CLW÷DL%=Ideal Body Weight. So if you weigh 170 pounds and your current body fat is 25 percent, your current lean percent is 75 (100 minus 25). Multiply 170 by 0.75 to get your CLW of 127.5. If your body fat goal is 16 percent, your DL% is 84 percent (100 minus 16). Divide 127.5 by 0.84 to get your new goal weight of 152 pounds.