Evolution, not just gluttony, led to obesity pandemic

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Evolution and the environment, not just gluttony, has led to a global obesity pandemic, with an estimated 1.5 billion people overweight - more than the number of undernourished people - an obesity conference was told today.

The mounting epidemic of obesity in children would see many die before their parents, said Kate Steinbeck, co-chair of the 10th International Congress on Obesity in Sydney.

''This is the first generation in history where children may die before their parents,'' Steinbeck told the conference.

Health experts at the week-long congress starting today said calls for the past 30 years for people to eat less fatty foods and exercise more had failed to combat global obesity.

Obesity had become an ''insidious killer and the major contributing cause of preventable diseases such as diabetes and heart disease,'' said conference co-chair Paul Zimmet.

''It is a disease with disastrous health, social and economic consequences,'' Zimmet told the conference.

Steinbeck said fighting obesity was not simply a matter of people eating less and exercising more, but discovering environmental and genetic contributors to obesity.

''We know this is not about gluttony -- it is the interaction of heredity and environment,'' said Steinbeck.

New obesity research has found that too little sleep and fats from fast food can alter a person's biology, making them more susceptible to overeating and less active, said the International Association for the Study of Obesity.

''Research into obesity should be given top priority to have any hope of combating the global pandemic,'' said Arne Vernon, president of the association.

Vernon said millions of obese people were being discriminated against and stigmatised, and often denied access to medical services. ''A growing proportion of morbidly obese people are at the extreme end of the spectrum but are stigmatised and ignored,'' he said. DIETARY EVOLUTION Dietary supplements and alternative treatments promising weight loss have minimal or no effect because they cannot match evolutionary influences that cause the body to conserve energy in times of famine, Dr Anne-Thea McGill told the conference.

McGill, senior lecturer in Population Health at the University of Auckland, said humans were designed to maximise their energy intake because their large brains used about one-quarter of their total energy expenditure.

''Early humans sought energy-dense food with high levels of fats, starches and sugars. We are genetically programmed to find foods with these qualities appealing,'' said McGill.

''However, highly energy-dense Western diets have had many of the flavour and micronutrients processed out of them. The artificial replacements in starchy, fatty and sugary foods make them over-palatable and easy to eat quickly.'' But too much processed food results in an excess energy intake deficient in micronutrients, producing a state of ''malnutrition'', which in turn sees the body react to a ''famine stress'' by storing fat around the upper body, said McGill.

''Many over-the-counter remedies such as concentrated herbal preparations, food extracts, minerals and vitamins are promoted as helping to decrease body weight,'' she said.

''However, they do not redress the nutrient imbalance from poor diets that produce obesity.''