The working hypothesis is that caloric restriction puts animals on a pathway favoring survival over growth and reproduction, says Ingram. “If you think about any organism’s use of energy, it’s got to evolve a mechanism for the most efficient use.” When sufficient energy is not available, he adds, the organism "begins to divert energy away from this growth-reproduction strategy.
Also, starvation is used to treat many illnesses and maladies. There are many books on starvation and its positive impact on health.
Starvation is good for health because it lacks calories, thus excess calories (the opposite of good health) are bad.