A study examining aging in mice has found that the hormonal changes that occur when mice eat significantly less may explain why a low calorie diet can extend their lifespan, far more so than can be explained by reduced obesity.

Because of this, reduced calorie diets extended the rodents’ lives far longer than an exercise program could.

The study applies only to rodents, which are different in some key ways from humans, but two studies which examined people who engage in high-volume exercise versus people who restricted their calorie intake had similar outcomes. Caloric restriction has physiological benefits that exercise alone does not.