Obesity. Body fat of a twelve-year-old boy being measured with callipers. The callipers are used to grip an area of skin, usually on the abdomen, thigh or upper arm. The distance between the tips of callipers is recorded and used to calculate the amount of subcutaneous fat present. From this a measure of the proportion of the body that is fat is obtained. Average body fat percentage for men is 10-20 percent, and for women is 17-27 percent. Body fat percentage measurement is usually conducted in specialist clinics for weight management.