cal activity. Total and resting metabolism together determine how many calories you burn up in a day.
Obesity is difficult to measure, but the most common estimate is from the Body Mass Index (BMI), which is calculated from a person's height and weight (Obesity). However, the BMI does not distinguish between fat and lean body mass, so a body builder may have a BMI which indicates obesity, but he may not have excess body fat. More accurate tests are hydrostatic weighing, skinfold measures, and bioelectric impedance, which distinguish between weight from fat and that from muscle. Hydrostatic weighing determines the body's density for estimates of body fat. A person with more adipose tissue is less dense than a person with more muscle, since muscle is denser than adipose tissue. Skinfold measures with calipers are used because thicker skinfolds in certain body areas indicate more fat content. Electrical impedance estimates fat content of the body because water transmits electricity better than fat, and lean body mass has more water than fat tissue does.
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