Overeating Blamed for the Obesity Epidemic in the United States

A new study claims that overeating, and not a lack of exercise, is to blame for the obesity epidemic in the United States, cautioning the obese that physical activity alone cannot fully compensate for the excess calorie intake.

Researchers at Deakin University (Melbourne, Australia) calculated what Americans should weigh today based on their current, higher food intake, and comparing this to their actual weight. They researchers hypothesized that if the subjects weighed more than projected, this would suggest a drop in physical activity. The researchers found that among children, the tests yielded a 100% match, leading them to conclude that changes in physical activity had had no impact whatsoever on the children growing fatter. According to the researchers, the reason that children in the U.S. have gained on average four kg heavier over the last three decades is due to a vast increase in the food ingested. Adults, on the other hand, have gained even more, with an average extra gain of eight kg when compared to the 1970's.

In fact, the researchers found that American adults actually weighed less than could be expected from their diet, which means that over that same period of time, the adults had been increasing, not decreasing, their physical activity. For the U.S. population to return to its leaner, healthier self, children would have to cut their food intake by about 350 calories a day--equal to one can of fizzy drink and a small portion of French fries--and adults would need to cut consumption by about 500 calories--the equivalent of a Big Mac hamburger. Alternatively, children would have to walk for an extra two-and-a-half hours a day, and adults for nearly two hours. The study was presented European Association for the Study of Obesity (EASO, London, United Kingdom) annual congress, held during May 2009 in Amsterdam (The Netherlands).

"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,” said study presenter and lead author Boyd Swinburn, M.D., a professor at the health faculty at Deakin. "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.”

The World Health Organization (WHO, Geneva, Switzerland) estimated that in 2005, about 1.6 billion adults were overweight worldwide, of which at least 400 million were obese.

Related Links:
Deakin University
European Association for the Study of Obesity
World Health Organization