So far, in a six-month trial study with participants who were moderately overweight at the start, researchers found that restriction produced lower body temperature, which they consider a marker of longevity, and lower insulin levels, which means a lower risk for diabetes. Some of these conclusions verge on the obvious: If someone who is overweight goes on a diet for six months, it seems pretty unsurprising that they'd be healthier at the end. In any case, a two-year study is set to begin soon.