Daijiworld Media Network - New Delhi

New Delhi, Jul 21: A new global study led by researchers at Duke University has found that higher caloric intake — not reduced physical activity — is the leading factor behind rising obesity rates worldwide, challenging long-held assumptions about the primary causes of weight gain.

Published in the journal PNAS, the study analyzed over 4,200 adults aged 18 to 60 from 34 populations across six continents, measuring daily energy expenditure, body fat percentage, and body mass index (BMI). Contrary to popular belief, the findings reveal that individuals in wealthier, industrialized nations burn as much or more energy daily as those in less-developed countries.

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

The study observed only a slight decline in size-adjusted energy expenditure with rising economic development — a change too small to account for the sharp increase in body fat.

“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 author and now a biology professor at Elon University.

The findings don’t dismiss the value of physical activity but reinforce that diet and exercise should be treated as complementary strategies in tackling obesity.

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

The team’s next step will be to pinpoint which specific aspects of diet in developed nations — such as processed foods, sugar consumption, or portion sizes — are most responsible for the global rise in obesity.

The study offers timely insights for public health policymakers and underscores the growing consensus that overconsumption, not under-exertion, is the key challenge in the modern obesity epidemic.