Daily protein and meal patterns affecting young men fed adequate and restricted energy intakes

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Abstract
Two 60-day N-balance studies with 14 young male MIT students were conducted to determine the effect of meal composition and pattern on the efficiency of dietary N utilization. Two levels of daily energy intake, one sufficient to maintain body weight and the other 80% of this level, were studied during each of two 30-day diet periods. Nonfat milk was the sole dietary protein source and provided 0.5 g/kg per day in experiment 1 and 0.4 g/kg per day in experiment 2. For 15-day diet periods at each energy level in experiment 1, protein was divided either equally among three meals (breakfast, lunch, and dinner) or two meals (lunch and dinner) with breakfast being “protein-free.” The distribution of energy intake among the different meals remained constant throughout the experiment. In experiment 2, the daily protein intake was divided among either two or three meals, but here the breakfast meal was omitted entirely when protein was provided only at lunch and dinner. Thus, the distribution of both protein and energy intake was varied among the meals in this experiment. In both experiments, and with each level of energy intake, the distribution of protein among meals did not significantly affect N balance. These results indicate, for levels of protein intake near maintenance requirements, that the distribution of protein among daily meals is not a significant factor in the efficiency of N utilization by young men.