Effect of Acute Starvation and Refeeding on Body Composition of Rats Fed Previously at Different Levels of Dietary Protein

Abstract

The effect of acute starvation and refeeding on body composition was studied in rats receiving high and low protein diets. For this purpose, weanling Sprague-Dawley male rats were fed a high protein diet (20% casein) or a low protein diet (5% casein) during an 8-week period, at the end of which the animals were starved for 2, 4, and 6 days. Rats in both dietary groups were treated similarly and after 6 days of starvation, each group was refed for 8 days with 5% or 20% casein diets. Body composition was somewhat similar at both protein levels. During starvation, the 2 groups of rats used their body fat reserves efficiently, although the malnourished animals utilized them at a more rapid rate. Higher body protein content was observed in all animals receiving the 20% casein diet. Although some differences among the groups studied are evident when the comparison is made in terms of average percentages, these differences are not as great as expected if the level of protein in the diet, the age of the animals, the length of time fed the experimental diets and the stress of acute starvation and refeeding are considered. When total body water, protein, and ash were related to fat-free weight, highly significant correlations were obtained. This information suggests, therefore, that the composition of the lean body remains relatively constant throughout all the experimental conditions, and depends on body size in growing animals.