Reducing Calories May Extend Life

A preliminary study in humans suggest that reducing calories may well extend life, say researchers in the Journal of the American Medical Association. Several evidence already exists to suggest that calorie restriction increases maximum life span in several animal species, co-author Dr Eric Ravussin, from Louisiana State University in Baton Rouge, said.

However, there hasn’t been any proof of it being the case in humans. This is the first step toward looking at the beneficial effects of calorie restriction in humans. Ravussin and his team enrolled 48 healthy overweight (but not obese) men and women in a six-month trial looking at the effects of calorie reduction.

Participants were in one of four groups: a control group, which followed a normal diet; a calorie restriction group, which received 25 percent less calories than the daily requirement; a third group, which exercised and reduced calorie intakes (12.5percent calorie restriction and 12.5 percent increase in energy expenditure); or a group that received a very low calorie diet, starting with 890kcal a day and then increased to maintain a 15 percent weight loss.

After six months, while patients in the control group lost about 1 percent of their weight, both calorie restriction groups (with or without exercise) lost approximately 10 percent. Individuals on the very low-calorie diet lost nearly 14 percent of their weight. The researchers also observed lower blood levels of insulin after fasting and a lower body temperature in all participants who undertook a restricted calorie regimen.

Body temperature and blood insulin levels are markers of longevity like grey hair or wrinkles, said Ravussin. It has been shown both in animals and humans that those with lower body temperature tend to live longer, and so do those with lower fasting insulin levels. Another important finding, according to Ravussin, was that less DNA damage seemed to occur in patients with lower calorie intakes.