Overeating to Blame For Obesity Epidemic

It's the calories we eat that makes us fat, not the exercise people often shirk. Researchers say American children have grown on average nine pounds heavier over the past three decades.

It's all that food we're eating that's making us fat. And it's got nothing to do with the amount of exercise we do or don't do. A new study finds that physical activity cannot fully compensate for excess calories. Study leader, Dr. Boyd Swinburn, a professor at the health faculty of Australia's Deakin University, spoke at an international obesity conference in Amsterdam today.

"There is no evidence that a marked reduction in physical activity has been a contributor to this epidemic in the United States, The increase in energy intake... virtually explained all of the weight gain."

Swinburn says American children have grown on average nine pounds heavier over the past three decades with adults putting on an extra 17 pounds. Surprisingly, researchers found that American adults weighed less than could be expected from their diet,

"which means that if anything over that period of time, the adults had been increasing their physical activity, not decreasing,"

Among children, the tests yielded a 100 percent match, leading researchers to conclude that changes in physical activity had had no impact whatsoever on America's children growing fatter. For the US population to return to its leaner, 1970s self, children would have to cut their intake by about 350 calories a day -- equal to one can of fizzy drink and a small portion of French fries, and adults by about 500 calories -- the equivalent of a Big Mac burger. Alternatively, children would have to walk for an extra two-and-a-half hours a day, and adults for nearly two hours, said Swinburn.

"Getting everybody to walk an extra two hours a day is not really a feasible option for countering the epidemic, We need to limit our expectations of what an increase in physical activity can achieve."

Swinburn stressed that the findings did not seek to negate the value of physical activity for weight control and overall health.

"But if we want to influence the underlying drivers (behind obesity), we have to have our eye much more on the energy intake side than on the physical activity side."

In short, he said, Americans must eat less. The World Health Organisation estimates that in 2005, about 1.6 billion adults were overweight, of which at least 400 million were obese. The conference was organised by the European Association for the Study of Obesity.