Body composition describes the different components that make up a person’s body weight. Body weight consists of both lean, metabolically active body mass (such as bone, muscle, organ tissue, blood, and everything else) and body fat (adipose tissue), which is not metabolically active. Your body fat percentage indicates how much fat your body contains. If you weigh 130 pounds and your body fat percentage is 10%, it means that your body consists of 13 pounds of fat and 117 pounds of lean body mass.

Total body fat percentage consists of two parts:

• Essential Fat – Essential fat is the amount necessary to maintain life and reproductive functions. Essential fat is 10-12% in women and 2-4% in men. The percentage is greater for women due to the requirements of childbearing and other hormonal functions.
  
• Storage Fat – Storage fat stores energy for the body and cushions and insulates internal organs, protecting those in the chest and abdomen. It consists mainly of fat deposited just under the skin. Women have slightly more storage fat than men.

Your body requires essential fat and a small amount of storage fat to function normally. In fact, it can be dangerous to strive for a body fat percentage that is too low. However, if you have too much storage fat, you may be beyond the healthy range.

Calculating Body Fat Percentage

This calculation is based on a formula developed by the U.S. Navy and estimates body fat percentage based on weight and various body measurements. It provides a rough estimate of body fat percentage that you can use consistently to determine if you are losing body fat and/or muscle. The best time to take measurements is in the morning because your body weight and waist measurements are the most accurate just after you wake up after 7 to 8 hours of sleep.