Eat Less -- Age Less

When nutrition is discussed as a means of slowing, stopping or reversing the aging processes the talk is usually about the foods and supplements to consume and the anti-nutrients to avoid. These things are certainly important. However, a recent study in the Journal of the American Medical Association (JAMA) identified not eating as significant in reducing the indicators of aging.

The study (JAMA 2006;295:1539–48) on calorie restriction in humans was not large and confined itself to already overweight adults. Forty-eight individuals were randomly divided into four groups, each assigned to a diet for six months: a normal weight-maintenance diet; a diet with 25% fewer calories than needed to maintain weight; a diet with 12.5% fewer calories than needed to maintain weight, plus a 12.5% increase in energy output through exercise; and a very-low-calorie diet providing 890 calories per day (generally, on average, adult eats about 2,000 calories per day). Essentially as a safety measure, the study was designed so that if dieters lost 15% of their body weight they would be switched to a diet that maintained that weight.

The people in all of the groups eating calorie-restricted diets lost weight, as one would expect. A number of other metabolic changes were also observed in the dieters, but not in the people who ate normally. These included a drop in fasting insulin levels in all of the dieters, and a decrease in core body temperature in the low-calorie and low-calorie-plus-exercise groups, but not in the very-low-calorie group.

Previous research evidence suggests these changes are signs that the aging process has slowed down. Resting energy output also decreased in the dieters, as did measures of cellular damage, adding to the evidence that during the study period the dieters aged less than the nondieters.

Of course the study was very small and the effects on people who are not already overweight were not studied. Nor are any possible long or longer term outcomes known. However, we can hope that the findings may find their way into some encouragement for people who are currently overweight (and there are certainly plenty of those). What a motivator - on top of feeling better, looking better and moving towards health restoration and reduced risk of disease, they also get measurably younger!