As noted in a recent research paper:

Caloric restriction (CR) causes a reduction in body temperature which is suggested to contribute to changes that increase lifespan. Moreover, low [body temperature] has been shown to improve health and longevity independent of CR. ... Based on current evidence, it is concluded that low [body temperature] plays an integral role in mediating the effects of CR on health and longevity, and that low [body temperature] may exert independent biological changes that increase lifespan. Our understanding of the overlap between CR- and [body temperature]-mediated longevity remains incomplete and should be explored in future research.

Calorie restriction causes increased health and longevity by triggering a set of programmed changes in the complex operation of metabolism. Even though the mechanisms of calorie restriction are far from completely understood, the programmed nature of this metabolic response is demonstrated by the fact that some strategic gene deletions can prevent calorie restricted laboratory animals from gaining health and longevity benefits.

There is reason to believe that enhanced longevity resulting from low body temperature is similarly a programmed response, for all that even less is known about the details of what is taking place under the hood. The hypothalamus is involved in both cases:

http://www.fightaging.org/archives/2010/10/body-temperature-and-longevity.php