Tuesday Aug 20, 2013 (foodconsumer.org) -- A human trial published in JAMA provides evidence to support the notion that calorie restriction or caloric restriction, that is, eating less calories per day, can increase the lifespan for humans.

Early animal studies have shown that calorie restriction can extend the lifespan of study animals like fries and rodents.  It is commonly believed that eating less calories can also increase humans' lifespan even though it is impossible to conduct a long term human trial to confirm the benefit.  

Eric Ravussin, Ph.D. from Pennington Biomedical Research Center, Louisiana State University in Baton Rouge, LA and colleagues conducted a 6-month randomized controlled trial of 48 healthy, sedentary men and women between March 2002 and August 2004 in Baton Rouge, La and found men and women who followed a calorie-restricted diet for six months had two biomarkers for longevity changed in a way to indicate that calorie restriction can increase the lifespan of humans.

For the trial, four groups of overweight men and women were assigned to receive for six months one of the four treatments,  weight maintenance diet, a diet with calorie intake reduced by 25% compared to that measured at baseline, a diet with calorie reduced by 12.5% and also exercise that increased energy expenditure by 12.5% compared with the energy intake and expenditure at baseline, and a very low calorie diet (890 kcal per day until 15% weight reduction, then followed by a weight maintenance diet.)

As a result, participants who followed a calorie restricted diet lost 10.4% to 13.9% of their body weight at six months of intervention.  At six months, fasting insulin levels were also significantly lowered in all individuals subject to the intervention, compared with their baseline levels.

The core body temperature and the DNA damage were also reduced in those who were subject to the calorie restriction intervention.

The authors say fasting insulin level and body temperature are two biomarkers of longevity.  

Calorie restriction can not only allow humans to live longer, but also healthier.   Studies have shown that people who eat fewer calories tend to have a lower risk for chronic diseases like cancer. It has been proved that caloric restriction slows the ageing process. (reporting by Jimmy Downs)