Effects of chronic caloric restriction and exercise training on body composition in mice.

Although exercise training and caloric restriciton (CR) cause some changes that are similar (such as weight loss), exercise does not retard aging, increase maximal lifespan or powerfully inhibit neoplastic growth. Contrasting the effects of CR and exercise might thus allow for identification of unique effects of CR that contribute to the anti‐aging and anti‐cancer phenotype. Therefore, our goals were to 1) create a mouse model of equal weight loss via CR and voluntary exercise, and 2) characterize these mice and identify changes unique to CR. Male C57Bl/6 mice were divided into 4 groups (n=10/group): 1) ad lib. food consumption, 2) 90% of ad lib., 3) 60% of ad lib., and 4) 90% of ad lib. + exercise wheel in cage. After 6‐months (at age 12‐months of age) body composition was determined using duel energy x‐ray absorptiometry (DEXA), and mice were sacrificed for tissue harvest. Mice in the 90% + exercise wheel group ran an average 6,000 – 4,000 meters per day throughout the study resulting in a body weight (27.1 ±0.9) what was well matched to the 60% CR group (26.7 ± 1.0). This matching of body weight was accompanied by a matching not only of % body fat (13.8 ± 1.1% and 13.4 ±1.2% respectively) but also fat distribution (abdominal %fat of 10.8 ±1.3 and 10.2 ± 1.1, leg %fat of 15.5 ± 0.9 and 14.9 ±0.8 in the 90% + exercise and 60% CR groups respectively). Both prostate gland weight and blood glucose concentration were reduced to the same levels by CR and exercise (prostate weights of 32±3 and 34±2 mg, blood glucose 168±7 and 174±12 mg/dl in the 90% + exercise and 60% CR groups respectively). In conclusion, we have successfully established a model where equal degrees of weight loss are achieved via caloric restriction and exercise training.