Every study done on any species has shown that calorie restriction expands lifespan. A recent study (via David Lat's Facebook) was done on earth worms:
Then, five years ago, studies in mice suggested that intermittent fasting would work just as well. These mice abstained from eating every other day, and lived longer then their gluttonous comrades—without really skimping on the total calories they consumed.
Now, scientists at Kyoto University have found the same thing in worms that fasted every third day. And they found a gene that regulates the effect, results reported in the journal Nature. Like the mice, these fasting worms did not cut their total calorie intake. But they boosted their lifespan by 50 percent, and showed fewer signs of physical decline than their peers. So go ahead, enjoy that extra slice of pie. Because tomorrow’s another day. To not eat.
Of course, neither modern medicine nor the American Medical Association will trumpet these results. There is no expensive drug to sell. And how many people want to hear that eating less is the fountain of youth?
I certainly respect people who make a cost-benefit lifestyle choice about their weight. If you're willing to die a few years (or decades) sooner because you like to eat, great. How dare I or anyone else suggest you live your life otherwise?
But the debate over whether calorie restriction will increase lifespan really is over - and probably has been over for years. The only open questions are, among others, whether intermittent fasting is as good as steady calorie restriction; and whether one can realize the benefits of calorie restriction through protein restriction:
"That was puzzling because it was the first time we hadn't seen agreement between mice and rats on calorie restriction and humans on calorie restriction," Dr Fontana explained. "But we know there are two major influences on IGF-1 levels: calorie intake and protein intake. So we decided to look at the influence of protein."
Dr Fontana and his associates next examined a population of strict vegans who consume no animal products, which results in a lower protein intake than most people, including those who practice calorie restriction. "The vegans had significantly less circulating IGF-1, even if they were heavier and had more body fat than CRONies," Dr Fontana stated. "Protein in the diet seemed to correlate with the lower levels of IGF-1. The strict vegans took in about 10 percent of their total calories from protein, whereas those on calorie restriction tended to get about 23 or 24 percent of calories from protein."
There are lots of interesting issues regarding calorie restriction. Whether it works? That has gone the way of the flat Earth theory.
Incidentally, if you're interested in calorie restriction, or life extension, or simply living a better life, check out the Life Extension Foundation. I've always had a sense of my own mortality, and thus have been a member since I was 22.