Food intake may contribute more to obesity than lack of exercise, study suggests

AMSTERDAM Conventional wisdom has it that the American obesity epidemic results from lack of exercise, but a study presented in the Netherlands Friday suggests otherwise.

The study, led by researchers in Australia and presented at the 17th European Congress on Obesity in Amsterdam, indicates that while exercise remains important, the main cause of the obesity epidemic is that Americans eat too much.

“To return to the average weights of the 1970s, we would need to reverse the increased food intake of about 350 calories a day for children and 500 calories a day for adults,” lead study author Boyd Swinburn of Australia’s Deakin University said in a statement. That would mean eliminating a can of soda or small portion of French fries from a child’s diet or a large hamburger from an adult’s.

The researchers started by testing 1,399 adults and 963 children to find how many calories they burn on an average day. They combined those results with national food supply data on how much food Americans ate between the 1970s and early 2000s. They then calculated how much weight they would expect Americans to have gained in the 30-year period if food intake were the sole influence, using national survey data that recorded the weight of Americans during that period.

“For adults, we predicted that they would be 10.8 kg heavier, but in fact they were 8.6 kg heavier,” Swinburn said. “That suggests that excess food intake still explains the weight gain, but that they may have been increases in physical activity over the 30 years that have blunted what would otherwise have been a higher weight gain.”

According to the Centers for Disease Control and Prevention, more than 30% of American adults are obese, which health experts define as having a body mass index of 30 or greater.