Body composition, energy utilization, and nitrogen metabolism with a severely restricted diet supplemented with...

To determine the effect of dietary modification on energy utilization during severely restrictive hypocaloric feeding, we measured body composition, energy deficit, and nitrogen metabolism in 13 obese women housed in a metabolic ward consuming a 2.1-MJ diet for 21 d with the three-carbon compounds dihydroxyacetone and pyruvate (DHAP), partially, isocalorically substituted for glucose. Body composition and amino acid (leucine) oxidation and turnover were determined before and after weight loss. Energy deficit was calculated from metabolic rates and compared with weight and fat loss. Subjects fed dihydroxyacetone and pyruvate showed a greater weight loss (DHAP = 6.5 +/- 0.3 kg, P = 5.6 +/- 0.2 kg), fat loss (DHAP = 4.3 +/- 0.2 kg, P = 3.5 +/- 0.1 kg), and weight and fat loss/4.25-MJ deficit (P less than 0.05 for all determinations). Nitrogen balance (urine and stool) and leucine metabolism were similar in both groups. We conclude that partial substitution of DHAP for six-carbon compounds of a 2.1-MJ diet will increase weight and fat loss.