Body Fat

Body Fat

The percentage body fat is calculated for males as 100*(-98.42 + 4.15*waist - 0.082*weight)/weight and for females as 100*(-76.76 + 4.15*waist - 0.082*weight)/weight.

The body fat calculation is based both on weight and waist size, and is exquisitely sensitive to the value for waist. If you lower the value for the weight without changing the waist, the calculation considers this as a loss of muscle mass, and hence the percent body fat goes up. Since it’s difficult to measure waist size accurately, this calculation is not useful when evaluating small changes in body weight.

The percentage of body weight considered "essential fat" is around 4% for men and 10% for women. The American Dietetic Association recommends that men have 15-18% body fat and women have 20-25% body fat. Healthy male athletes might be as low as 5-12% body fat, and healthy female athletes could be as low as 10-20%. The American Council on Exercise recommends men's body fat should be 6-25%, and women's should be 14-31%.