Effects of moderate physical activity (90 min at 45-50% of maximal O₂ uptake 2 times daily) and "high" (2.5 g protein · kg¹ · day¹, n = 6) or "normal" protein intake (1.0 g protein · kg¹ · day¹, n = 8) on the pattern and rate of 24-h macronutrient utilization in healthy adult men were compared after a diet-exercise-adjustment period of 6 days. Energy turnover (ET) was determined by indirect and direct (suit) calorimetry, and "protein oxidation" was determined by a 24-h continuous intravenous infusion of [1-¹³C]leucine. Subjects were in slight positive energy balance during both studies. Protein contributed to a higher (22 vs. 10%) and carbohydrate (CHO) a lower (33 vs. 58%) proportion of total 24-h ET on the high- vs. normal-protein intake. The highest contribution of fat to ET was seen postexercise during fasting (73 and 61% of ET for high and normal, respectively). With the high-protein diet the subjects were in a positive protein (P < 0.001) and CHO balance (P < 0.05) and a negative fat balance (P < 0.05). The increased ET postexercise was not explained by increased rates of urea production and/or protein synthesis.

carbohydrate; direct calorimetry; energy turnover; fat; indirect calorimetry; macronutrient utilization; obesity; physical exercise; protein; stable isotopes

This article has been cited by other articles:

				P. B Mikkelsen, S. Toubro, and A. Astrup Effect of fat-reduced diets on 24-h energy expenditure: comparisons between animal protein, vegetable protein, and carbohydrate Am. J. Clinical Nutrition, November 1, 2000; 72(5): 1135 - 1141. [Abstract] [Full Text] [PDF]

				D. Tomé and C. Bos Dietary Protein and Nitrogen Utilization J. Nutr., July 1, 2000; 130(7): 1868S - 1873. [Abstract] [Full Text]