Calorie restriction and skeletal mass in rhesus monkeys (Macaca mulatta): Evidence for an effect mediated through changes in body size

Little is known regarding the effects of prolonged calorie restriction (CR) on skeletal health. We investigated long-term(ll years) and short-term (12 months) effects of moderate CR on bone mass and biochemical indices of bon e metabolism in male rhesus monkeys across a range of ages. A lower bone ma ss in long-term CR monkeys was accounted for by adjusting for age and body weight differences. A further analysis indicated that lean mass, but not fa t mass, was a strong predictor of bone mass in both CR and control monkeys. No effect of short-term CR on bone mass was observed in older monkeys (mea n age, 19 years), although young monkeys (4 years) subjected to short-term CR exhibited slower gains in total body bone density and content than age-m atched controls. Neither biochemical markers of bone turnover nor hormonal regulators of bone metabolism were affected by long-term CR. Although osteo calcin concentrations were significantly lower in young restricted males af ter 1 month on 30% CR in the short-term study, they were no longer differen t from control values by 6 months on 30% CR.