More than a lack of exercise, a higher caloric intake may be the primary driver of obesity worldwide, finds a study.

While many experts have offered that rising obesity rates are due to declining physical activity as societies become more industrialised, the findings led by researchers from Duke University in the US, show that people in wealthier countries expend just as much -- or even more -- energy daily.

“It’s clear that changes in diet, not reduced activity, are the main cause of obesity,” said Herman Pontzer, principal investigator and Professor in the Department of Evolutionary Anthropology at the varsity.