Following up on recently published research into changes in body temperature brought about by the practice of calorie restriction in humans, I see that a release from a few days ago contains some interesting remarks from the researcher:
Individuals who significantly reduce their calorie intake have lower core body temperatures compared to those who eat more. The new finding matches research in animals. Mice and rats consuming fewer calories also have lower core body temperatures, and those animals live significantly longer than littermates eating a standard diet. ... What is interesting about that is endurance athletes, who are the same age and are equally lean, don't have similar reductions in body temperature.
What we don't know is whether there is a cause/effect relationship or whether this is just an association. But in animal studies, it's been consistently true that those with lower core body temperatures live longer. ... in an unrelated study called the Baltimore Longitudinal Study of Aging, scientists found that men who had lower core body temperatures, probably for genetic reasons, lived significantly longer than men with higher body temperatures. So it appears body temperature may predict longevity in humans, too.
For now, animal models suggest that simply lowering body temperature isn't enough to increase lifespan. In mice and rats that regularly swam in cold water, core body temperature dropped due to exposure to the cold water. But those animals didn't live any longer than normal rodents. Fontana says it appears that how lower temperatures are achieved is important. "I don't think it ever will be possible to be overweight and smoking and drinking and then take a pill, or several pills, to lower body temperature and lengthen lifespan," he says. "What may be possible, however, is to do mild calorie restriction, to eat a very good diet, get mild exercise and then take a drug of some kind that could provide benefits similar to those seen in severe calorie restriction."
Calorie restriction is chiefly interesting for its beneficial effects on health and longevity - which are nothing short of stunning in comparison to any presently available medical technology. It's the best present option for immediately and rapidly improving the health of basically healthy people. The evidence for it and the effects in studied human populations are so good that - if you are essentially healthy, in good shape, and would like to stay that way for as long as possible - you'd really have to have be digging for excuses not to be practicing calorie restriction.
All that said, calorie restriction is only slowing aging - and if we want to do better, to avoid becoming frail and aging to death, the only viable path forward is biotechnology along the lines of the Strategies for Engineered Negligible Senescence. If repair technologies for our biology are not developed soon enough, then all we gain through calorie restriction is a healthy life, probably a little longer, almost certainly with a lower cost of medical treatment and fewer chronic diseases of aging. To do better than that, to regain the vigor and health of youth and obtain extra decades of life, we need to support and encourage rapid advances in medical technology.