It looks like Benjamin Franklin was correct when he stated: “To lengthen thy life, lessen thy meals.” Research suggests that cutting calories overall can mimic the effect of healthy antioxidants to decrease age-related deterioration in your body and brain.
In other words, one of the strongest indicators of longevity is not just what you eat but how much of it you eat. Those who eat smaller tend to live longer.
However, if you take this to an extreme, go cold turkey, and severely clamp down on calories, your body can interpret the situation as a stressor. In one study, experimental animals put on a two-week fast showed spikes in their stress hormones along with decreases in their cardiac muscle volume and output. That form of caloric restriction was terribly unhealthy.
Likewise in humans, fasting for a full two days led to symptoms of insulin resistance and, as you might predict from this result, induced diabetes in some cases. Along with increased stress hormones and insulin resistance, your systems can go into what is commonly called “starvation mode," in which your metabolism slows down (you’re burning fewer calories). Even worse, your body can hold on to the fat it does have, essentially frustrating the very point of the fast in the first place.