A long-running study on calorie restriction and healthy longevity in rhesus monkeys has been funded out to 2011: "The idea that fewer calories can extend lifespan and improve health has a long experimental history. ... rhesus macaques in the Wisconsin study [offer] perhaps the best window into a phenomenon that is the only proven dietary way to extend lifespan. ... The animals on a restricted diet exhibit 70 percent less body fat, and the fat tissue itself [is] very different from the fat tissue in the control animals, those allowed to eat freely. His group has also observed that the animals that eat less have less insulin in their bloodstreams and less insulin resistance ... So far, we've had complete protection from type 2 diabetes. Normally, 30 percent of the animals in a research colony will exhibit type 2 diabetes. ... 90 percent of the animals who began the study on a reduced diet are still alive, while only 70 percent of the animals allowed to eat freely have survived to this stage."

Link: http://www.news.wisc.edu/12649.html