Harmful artificial trans fats are to be banned as figures yesterday revealed that more than half of the population could be obese within 25 years. Researchers claimed that 86 per cent of men were expected to be overweight in 15 years and 70 per cent of women within 20 years.



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It is anticipated that obesity could cost as much as £45 billion a year by 2050, to pay for growing incidents of diabetes, strokes and heart disease as well as the loss of earnings by those too heavy to work.

Part of the problem has been attributed to artery-clogging trans fats, which are largely man-made and found in products such as chocolate, cereals and fast food. Like saturated fats, they are linked to raised levels of cholesterol in the blood and an increased risk of heart disease and stroke.

Alan Johnson, the Health Secretary, said he would ask the food watchdog to consider the introduction of stricter measures.

"I will be asking the Food Standards Agency to conduct an immediate investigation into the evidence in this area to see if there is anything more we should be asking the food industry to do," he said. Mr Johnson said he was determined to fight the problem of obesity in light of the results of the Foresight study, commissioned by the Government in 2005. He compared the issue to global warming.

"For the first time, we are clear about the magnitude of the problem: we are facing a potential crisis on the scale of climate change and it is in everybody's interest to turn things round," he said.

Details of the study, carried out by Prof Klim McPherson, of Oxford University, and Tim Marsh, of the National Heart Foundation, will be released later this week. Mr Johnson said it was the responsibility of individuals, as well as society, to find a solution.

"It cannot be tackled by Government action alone," he said. "We have made progress with improved physical activity levels at school, healthier school food for children, clearer food labelling and tougher restrictions on advertising foods high in fat and sugar to children. But we know that we need to go further and faster."

Last month, a report by Gordon Brown's former adviser, Sir Derek Wanless, found that obesity was one of the problems that would "overwhelm" the NHS in the future.

Targeting trans fats is one of the ways the Government intends to tackle the problem. Many supermarkets have already started phasing out the use of trans fats in thousands of their own-brand food products. In addition, hundreds of branded foods have been reformulated to avoid using the fats.

Although they can form naturally in dairy products, most of the trans fats in the diet come from processed food. They are added by manufacturers to extend shelf life and enhance the taste.

They are formed when liquid vegetable oil is "hydrogenated", or made solid, for use in baking and processed foods. They can also be created when oils are fried.

Last December, New York became the first city in America to ban trans fats from all its 24,000 restaurants by 2008.

Prof Peter Weissberg, the British Heart Foundation medical director, welcomed a ban on trans fats.

"There is no point in having things in our daily diet that might do harm," he said. "But there is more to the issue - how do we tackle the problem of obesity and the fact that people are fatter, eating the wrong foods and not taking any exercise?"