Last updated at 10:13 11 December 2007

Being fit helps you live longer - even when you're fat, an American study has found.

Striking findings show the fittest fat men and women aged 60 and over are more likely to live to a ripe old age than their averagely weighted or slim - and less fit - peers.

The message seems to contradict current anxieties about an obesity epidemic and constant messages to lose weight.

But U.S. researchers led by Dr Steven Blair claim all older people, including those who are obese, can benefit from increasing their activity levels.

Their study, published in the Journal of the American Medical Association, assessed the fitness of 2,600 adults aged 60 or older and measured their Body Mass Index - an obesity indicator - and percentage body fat.

Over 12 years, 450 died and researchers found they had lower fitness levels than the survivors, regardless of BMI.

Dr Blair said: "We observed that fit obese individuals had a lower risk of all-cause mortality than did unfit, normalweight or lean individuals.

"It may be possible to reduce all-cause death rates among older adults by promoting regular physical activity - such as brisk walking for 30 minutes or more most days."