A calorie-restricted diet can extend the lives of organisms from yeast to fruit flies to rodents, as well as improving their health and preventing disease. But just because cutting calories helps animals with short lifespans doesn’t mean that humans will reap similar benefits. So the 2009 discovery that calorie-restricted diets also increase the longevity of already-longer-lived rhesus monkeys was exciting news.
But don’t pull out a calorie calculator quite yet. The latest word on the subject, from a new paper in Nature, suggests that the 2009 study might not tell the whole story: this team found that caloric restriction doesn’t actually grant rhesus monkeys longer lives.
Elderly people who ate one-third fewer calories for three months showed marked improvements on memory tests, according to a small new study that’s just the latest evidence linking caloric restriction to good health. There is growing interest in the potential benefits of calorie restricted diets, after research in animals suggested they might be able to improve lifespan and delay the onset of age-related disease. However, it is still not certain whether this would be the case in humans – and the the levels of “caloric restriction” involved are severe [BBC News].
The study involved 50 elderly people who ranged from normal weight to overweight. Members of one group were asked to cut their daily calorie consumption by 30 percent, primarily by reducing their portions, another group kept their calorie intake the same but ate more of the healthy, unsaturated fats found in fish and olive oil, while a final group made no dietary changes. When the volunteers took memory tests after three months, only the calorie-restriction group showed improvement. Neuroscientist Mark Mattson comments that the study “adds to considerable evidence from animal and human studies that high calorie intake is not only bad for your heart, but it’s bad for your brain” [Technology Review].