Low-calorie diet: If you’re a rhesus monkey, a low-calorie diet may not help you live longer, reports a new study that overturns previous findings.
The longevity diet’s premise is seductively simple: cutting your calorie intake well below your usual diet will add years to your life.
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New research published on Wednesday, however, shows the extreme, emaciating diet doesn’t increase lifespan in rhesus monkeys, the closest human relatives to try it in a rigorous, long-running study. While caveats remain, outside experts regarded the findings as definitive, particularly when combined with those from a similar study.
“If there’s a way to manipulate the human diet to let us live longer, we haven’t figured it out yet and it may not exist,” said biologist Steven Austad of the University of Texas Health Science Center’s Barshop Institute for Longevity and Aging Studies, who wrote an analysis of the study in Nature.
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Since 1934, research has shown that lab rats, mice, yeast, fruit flies and round worms fed 10 percent to 40 percent fewer calories than their free-eating peers lived some 30 percent longer. In some studies, they lived twice as long.
Such findings have spawned a growing community of believers who seek better health and longer life in calorie-restricted (CR)diets, as promised in the 2005 book “The Longevity Diet,” including 5,000 members of the CR Society International. The research has also prompted companies like Procter Gamble and Nu Skin Enterprises to develop drugs to mimic the effects of calorie restriction.
The new study, from the National Institute on Aging, part of the U.S. National Institutes of Health, suggests a surprising disconnect between health and lifespan. It found that most of the 57 calorie-restricted monkeys had healthier hearts and immune systems and lower rates of diabetes, cancer or other ills than the 64 control monkeys. But there was no longevity pay-off.
“You can argue that the calorie-restricted animals are healthier,” said Austad. “They have better cholesterol profiles, less muscle loss, less disease. But it didn’t translate into greater longevity. What we learn from this is you can un-link health and longevity.”
The NIA study, launched in 1987, is one of two investigating whether eating just 70 percent of the calories in a standard lab diet extends life in a long-lived primate. The Wisconsin National Primate Research Center’s study, begun in 1989, also uses rhesus monkeys, whose physiology, genetics and median lifespan (27 years) are closer to humans than are the rodents in earlier calorie-restriction research.