American Journal of Clinical Nutrition, Vol 26, 144-149, Copyright © 1973 by The American Society for Clinical Nutrition, Inc.

Body composition changes during weight loss estimated from energy, nitrogen, sodium, and potassium balances

¹ From the Department of Nutritional Sciences, University of California at Berkeley

Changes in the body composition of six obese women were studied during two periods while the subjects were fed isocaloric liquid diets of different protein content. During the first 12-day period, the diet was protein free; during the second 12 days, the subjects received a diet containing 3 g N/day. The diets contained 25% of the calories necessary to maintain initial weight.

Estimates were made from measurements of energy, nitrogen, sodium, and potassium balances. The mean loss of weight was the same for both diets, but the loss of fat-free protoplasm and potassium was less when the diet contained protein than when it did not. The estimate of changes in body composition made from sodium and potassium balances were compared with those obtained from energy and nitrogen balances. The limitations of the techniques were also discussed.