1 Calculate your Total Daily Energy Expenditure
How to Calculate Your Body Mass Index
Your body fat percentage is simply the percentage of fat your body contains. If you weigh 140 pounds and are 10% fat, it means that your body consists of 14 pounds of fat and 126 pounds lean body mass (bone, muscle, organ tissue, blood).
A certain amount of fat is essential to bodily functions. Fat regulates body temperature, cushions and insulates organs and tissues and is the main form of the body's energy storage.
Body Mass Index (BMI) -
The BMI is the ratio of your weight to the square of your height. The number is proportional to your body shape. Generally, the number is small for thin people and large for fat people. People with a BMI 25 or greater are considered overweight, unless they have a very muscular body. The BMI does not consider the fat/muscle ratio, and a healthy, muscular individual with a low percentage of body fat may be classified obese using the BMI formula. This is a well-known deficiency of the BMI formula. If your BMI is 25 or greater, and your Waist-to-Height ratio is less than 0.5 and your Percent Body Fat is in the "athlete" or "fitness" category, you are probably muscular and not fat.
Waist-to-Height Ratio -
The Waist-to-Height ratio is determined by dividing the waist circumference by the height. Waist-to-Height ratios of 0.5 or greater are indicative of intra-abdominal fat for both men and women and are associated with a greater risk of cardiovascular disease. A study found that persons with a normal BMI but a large waist circumference, corresponding approximately to a Waist-to-Height ratio of 0.55, had a 20% higher mortality risk than persons with a normal waist size.
Percent Body Fat -
The percent body fat is calculated using the formulas developed by Hodgdon and Beckett at the Naval Health Research Center in 1984. The formulas require the measurements to be in centimeters with an accuracy of 0.5 cm. However, the form above has been adjusted to accept measurements in inches. Men and women require different methods for measuring because men accumulate fat mostly in the abdomen (the "apple" body shape or "beer belly"), while women accumulate fat in their abdomen and hips (the "pear" body shape). The equations take this into consideration.