Parents could outlive their children as obesity spreads

Parents might soon be outliving their children because of the rising level of obesity among youngsters who are eating high-calorie diets yet taking little exercise, a specialist in nutrition said yesterday.

The lifespan of seriously obese children can be shortened by several years. They succumb to potentially fatal disorders such as heart disease and type-2 diabetes.

Andrew Prentice, professor of international nutrition at the London School of Hygiene and Tropical Medicine, told the British Association's Science Festival in Leicester that the prediction of rising obesity causing falling longevity among the present generation of children could easily come true.

"These young people, who are being ambushed by the environment, are storing up for themselves enormous ill-health for the future. We also know that the younger you are when you are obese has severe long-lasting effects on the ill health associated with it."

About one in five Britons is clinically obese and about half are seriously overweight, but the proportion is rising among children and adolescents, mainly because of a sedentary lifestyle and a fast food diet.

"This is a fascinating moment in human evolution because it is happening so suddenly," Professor Prentice told the Science Festival. "The kids in particular are very susceptible to all these changes in habit. The longer you are obese, the more likely it is that you will accrue all the damaging side-effects of obesity.

"The important point is that it is biologically predictable. We've spent millions of pounds trying to find out something weird and wonderful about our metabolism that causes people to become obese and I've come to the conclusion that it is blindingly obvious, there is no mystery at all and it is a perfectly predictable biological response to a changed environment," he said. "The kids of today aren't gluttonous or lazy. They've been ambushed by living in an environment where they haven't seen any different."

Human body shape is undergoing one of the most dramatic shifts in evolutionary history, he said. "The last such shift in our shape occurred about two centuries ago in Europe and involved an increase in average adult height by 30cm or more," Professor Prentice said.

An increase in height was linked with a better diet and health, which helped to extend longevity. However, an increase in girth among the young today would be very damaging for their long-term health, he said.

Obesity is a risk factor for a range of chronic diseases from relatively minor ailments such as breathlessness or varicose veins to quite serious conditions such as osteoarthritis and high blood pressure, to frequently fatal conditions such as diabetes, stroke and coronary heart disease. Seriously obese children could expect to lose up to nine years on average through developing diseases that were not as common among their parents.

"The prognostications are not good. If anything, the obesity pandemic is gathering pace rather than slowing down, and current interventions are only marginally effective and very expensive," the professor said.