The scientists from Glasgow University in Scotland arrived at this conclusion based on the results of an animal study.

The study which compared the growth rate, success of reproduction and life span of stickleback fish, found that fish given a "binge then diet" food regime had a reduced life span of up to 25%.

The scientists believe their findings could have implications for teenagers and children who follow extreme patterns of dieting while they are still growing.

They say uneven growth, due to the fluctuation in the amount eaten per day, is responsible for the increase in the risk of sudden death.

The study was led by Professor Neil Metcalfe from the university's faculty of biomedical and life sciences, who says 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 - but their life span was three-quarters that of animals eating a constant amount every day.

Professor Metcalfe says the difference in life span was not a consequence of more rapid ageing but an increase in the risk of sudden death, possibly because the body tissues are more likely to have imperfections due to growth spurts.

Professor Metcalfe says similar results would most likely be seen in other animals with short life spans that grow throughout their lives and could also be applied to humans who follow extreme patterns of dieting which would only occur in children and teenagers.

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

Regional health and development agencies could work together to promote seasonal "five a day" choices which would benefit the environment as well as health and the VAT system could be linked directly with healthy eating. Improving production systems would have significant effects on the nutritional quality of foods - quality assurance schemes that take this into account could be beneficial. As food chains become more complex there is a need for more transparency about risks and the sources of ingredients. More support for food production and marketing that also enhances biodiversity, such as salt marsh lamb, and for novel systems such as farming warm water fish indoors, would have benefits for health and for the environment.

Professor Philip Lowe, Director of Relu, said: "Many people today feel out of touch with the land. But the link between rural land and the food we eat is, of course, fundamental to our very existence. There may be ways in which policy can key into that interdependence and benefit both our well being and our environment.

"For example, many people like to eat local food, but we are just beginning to understand the complexity of food miles and to see that local production cannot be the whole answer. Eating foods in season is equally important.

"We strive for a healthy diet, and are told to eat more fish, but how can that be balanced with conserving wild fish stocks? Fish farming hasn't had a good press recently either, but could we do this differently?

"Would changes to the tax system encourage consumption of healthier foods? Or would it be more effective to manipulate the foods people do eat, to make them healthier? And what about food scares and the risks in the food chain? These are all issues that Relu is starting to explore in 'Land to Mouth'."

relu.ac/