Page last updated at 00:58 GMT, Wednesday, 30 April 2008 01:58 UK

Crash diets 'may reduce lifespan'

Threespine Stickleback
The study compared the growth rate of stickleback fish

Scottish scientists have found that binge eating and crash dieting may significantly reduce life expectancy.

Researchers from Glasgow University observed that fish given a "binge then diet" food regime had a reduced lifespan of up to 25%.

Their study compared the growth rate, success of reproduction and lifespan of stickleback fish.

They believe the findings could have implications for teenagers and children who follow extreme patterns of dieting.

This is because they are still growing.

The study was conducted by researchers in the University of Glasgow's faculty of biomedical and life sciences.

The findings are published in the journal, Proceedings of the Royal Society B.

Professor Neil Metcalfe said: "The fish on the fluctuating diet put just as much effort into breeding - the males became brightly coloured as usual and the females produced the normal number of eggs.

"However, on average their lifespan was three-quarters that of animals eating a constant amount every day."

The research found that the difference in lifespan was not a consequence of more rapid ageing but an increase in the risk of sudden death.

'Extreme patterns'

Professor Metcalfe added: "It seems that uneven growth, due to the fluctuation in the amount eaten per day, is responsible for the increase in the risk of sudden death.

"This is possibly because the body tissues are more likely to have imperfections due to growth spurts."

Similar results would most likely be seen in other animals with short lifespans that grow throughout their lives, said Prof Metcalfe.

But it could also be applied to humans who follow extreme patterns of dieting, he went on, and could be seen in teenagers and children who are still growing.

Prof Metcalfe said: "Applying this to humans, it would only occur in children and teenagers.

"But it would be for extreme switches in diet. Just skipping lunches would not have any effect, but if they had several weeks of one diet followed by several weeks of the extreme opposite, then there could be an effect."

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