Effect of reduced energy intake versus increased physical activity on the outcome of nitrogen balance experiments in man

Abstract

The effects of energy deficiency created by a reduced energy intake versus an increased physical activity on urinary nitrogen excretion, nitrogen balance and the biological value of the dietary protein (0.57 g/kg/day from a mixed diet) are reported. Two experiments, 21 and 27 days respectively, designed to even out possible effects of time on nitrogen balance, were conducted on 12 young adult men and women. During energy deficiency, urinary nitrogen increased while nitrogen balance and biological value decreased. No significant differences between the two kinds of energy deficiency were found but the effect on the parameters studied tended to be less pronounced the longer the subjects had been on the experimental diets.