Previous research using mice has suggested that severe caloric restriction has the potential of extending human life span. Many people have been conducting the experiment on themselves with the hope of postponing their inevitable demise. But a new long-term study on monkeys found no evidence that caloric restriction extends life span.
Calories and longevity
Studies investigating the effect of caloric restriction diets laboratory animals such as mice and earthworms have shown that limiting calorie intake may extend life span. Researchers have suggested that eating up to 40 percent fewer calories than is considered normal could mimic the effects of resveratrol, a compound in red wine that has an affect on genes linked to longevity.
In an effort to see if caloric restriction could have the same effect on humans, researchers climbed further up the evolutionary tree and conducted studies on monkeys. In 1987, researchers at both the Wisconsin National Primate Research Center and the National Institute of Aging started caloric restriction experiments on rhesus macaques.
In 2009 the Wisconsin researchers reported that monkeys on caloric restriction showed an increase in lifespan. However, the study from the National Institute on Aging, published online in Nature on August 29, reported that after 23 years, no evidence emerged that caloric restriction extended lifespan compared to rhesus macaques on a normal diet.
Signs of research bias
According to Steven N. Austad, a professor at University of Texas Health Science Center San Antonio, who wrote an sidebar to the Nature report, an unrestricted diet may have been the key flaw in the Wisconsin study.
He noted that monkeys in the control group of that study were allowed to eat a high sugar diet whenever they wanted, which made them more likely to develop diabetes and other health complications that led to an earlier death. The calorie-restricted monkeys lived longer, but the same results may have been achieved with a more conventional diet regimen.
The Wisconsin researchers also eliminated monkeys who died from non-disease-related causes from their statistics. Had they remained in the analysis, differences reported in longevity between the restricted diet monkeys and the controls would have narrowed.
Live healthier longer
In the National Institute of Aging study, control monkeys ate a fairly healthy, low-sugar diet. Restricted-diet monkeys in that study had somewhat healthier measures of blood sugar and a cholesterol levels than the controls, but they didn’t live any longer.
It’s also interesting to note that wild rhesus macaques weigh less than all the monkeys in both studies.
The NIH study suggests that starving yourself to live longer could be a Quixotic pursuit. No diet likely exists that will help you reach triple figures. However, if you eat right, exercise and maintain a healthy weight, it’s more likely you will enjoy a higher quality of life until you die.