Percentage of body fat in body composition measurement, taking into account not only your weight but the percentage of weight that is composed of fat. Since muscle takes up less space, those with low body fat formed a more toned. Bodybuilders and fitness competitors struggle to extremely low levels of body fat to make your muscles appear more healthy level of body fat defined.A contributes to your overall health. Men over 25 percent body fat and women 30 percent are considered obese and at risk for multiple health problems. Islower muscles pop when your body fat - which is why low-fat is good for body builders. A pack of six for men occurs at about 8-12 percent of body fat.