London: People who burn calories at a slower rate are likely to live more as compared to people who have fast metabolism.

The findings, based on a study of more than 600 volunteers, suggest that an increased metabolic rate actually speeds up the ageing process, a daily newspaper said.

Experiments on animals have earlier shown a strong link between longevity and metabolic rate but there has been little evidence to suggest so in humans.

American researchers have now compared the metabolic rate and lifespan of 652 healthy 'Pima indians' in Arizona over a 21-year period.

The scientists, from the National Institutes of Health, conducted experiments to measure how quickly the volunteers' bodies converted food into energy over 24 hours, newspaper said.

They also measured their resting metabolic rate, which is how much energy a body uses simply to keep the lungs and heart working.

In a report in the Journal of Clinical Endocrinology and Metabolism, the team said those persons with a higher metabolic rate tended to die earlier.

Researcher Reiner Jumpertz said, "We found that higher endogenous metabolic rate – which is how much energy the body uses for normal body functions – is a risk factor for earlier mortality. This increased metabolic rate may lead to earlier organ damage."

But the findings do not apply to energy burnt up by exercise. "This activity clearly has beneficial effects on health," Jumpertz added.