Energy restriction-induced changes in body composition are age specific in mice.

Restricting energy intake while supplying adequate micronutrients slows aging and extends maximal lifespan, whereas loss of body weight with exercise training does not. Our goal was to test the hypothesis that weight loss via energy restriction (ER) alters body composition in a way that is: 1) distinct from exercise-induced weight loss; and 2) conserved regardless of the age at which ER is initiated. An experimental model was developed where matched losses in weight could be induced with 6 mo of ER (approximately 55% of ad libitum energy intake) or voluntary exercise on a running wheel in adult (12 mo) male C57BL/6 mice and a similar amount of ER-induced weight loss could be induced in aged mice (24 mo).