Key Points

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.

In an article recently published in the journal PNAS, the researchers analysed thousands of measurements of daily energy expenditure, body fat percentage, and body mass index (BMI) from more than 4,200 adults aged 18 to 60 across 34 populations spanning six continents.

While a marginal decrease was found in size-adjusted total energy expenditure with economic development, differences in total energy expenditure explained only a fraction of the increase in body fat that accompanied development, said the researchers.

"This suggests that other factors, such as dietary changes, are driving the increases in body fat that we see with increasing economic development,” explained Amanda McGrosky, lead investigator and postdoctoral researcher at Duke at the time of the study. McGrosky is now an assistant professor of biology at Elon University in the US.

Notably, the findings do not mean that efforts to promote physical activity should be minimised.

Instead, the data support an emerging consensus that both diet and exercise should be prioritised, the researchers said.

“Diet and physical activity should be viewed as essential and complementary, rather than interchangeable,” the study noted.

The team will next work to identify which aspects of diet in developed countries are most responsible for the rise in obesity.

- IANS