measurments and calculations

basal metabolic rate

Basal metabolic rate (BMR) is the number of calories metabolized at rest during 24 hours and is the key to effective weight management. For a typical patient, BMR accounts for more than ninety percent of total daily expenditure - more than ninety percent of calories are burned while the patient is at rest.

The basal metabolic rate is determined by fat-free mass since only fat-free mass metabolizes. The formula is a simple one - the larger a patient's fat-free mass, the greater the rate of caloric expenditure.

The equation used by the analyzer to predict BMR, based upon Grande and Keys (1), is as follows:

    BMR (calories/day) = 14.15 * Fat-Free Mass (lb)

Converted to metric, the equation is as follows:

    BMR (calories/day) = 31.2 * Fat-Free Mass (kg)

While caloric expenditure is elevated during exercise and occupational activity, the main benefit of exercise is the maintenance of fat-free mass. More fat-free mass means greater caloric consumption all day long, even when the patient is asleep!

Dieting alone may cause a reduction in fat-free mass, and can actually reduce the body's ability to burn calories. The holy grail of weight management is to maintain or increase fat-free mass. This is not always possible during periods of weight loss. So the goal is to minimize reduction of fat-free mass. A typical patient will experience a loss of 0.45 pounds of fat-free mass and 0.55 pounds of fat mass for each pound of weight loss while dieting without maintenance exercise.

Reference:
1Grande F, Keys A. Body weight, body composition, and calorie status. In R. S. Goodhart and M. E. Shils, eds. Modern nutrition in health and disease, 27, 1980. Philadelphia: Lea & Febiger.
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