Dr Michael Mosley, a presenter on BBC science show 'Horizon', said that ongoing research suggested that a high metabolic rate is a risk factor for earlier mortality.

And he revealed that communities in Japan and the U.S. that follow strict, low-calorie diets appear to live longer than the global average.

Dr Mosley said of calorie restriction diets, which are often as low as 600 calories a day that over a period of time the body adapts to it and slows down the metabolism rate, which eventually helps in prolonging our life.

"The bottom line is that it is the only thing that's ever really been shown to prolong life," the Daily Mail quoted him as saying.

"Ultimately, ageing is a product of a high metabolic rate, which in turn increases the number of free radicals we consume.

"If you stress the body out by restricting calories or fasting, this seems to cause it to adapt and slow the metabolism down. It's a version of "what doesn't kill you makes you stronger"," he said.

The 55-year-old said he did not believe it was necessary to eat three meals a day because 'what we think of as hunger is mainly habit'.

In a new Horizon programme, he suggested that intermittent fasting could offer the same benefits as calorie restriction by reducing the growth of hormone IGF-1.

While the hormone maintains and repairs tissue, high levels have proven to contribute towards cancer and ageing.

His comments, made to the Radio Times, come after the Institute of Health Ageing at University College London suggested that eating 40 percent less could help extend a person's life by 20 years.

"If you reduce the diet of a rat by 40 per cent it will live for 20 per cent longer. So we would be talking 20 years of human life," a researcher said.

"This has shown on all sorts of organisms, even Labradors," the researcher added. (ANI)