A new study from Duke University’s Pontzer Lab reveals that rising obesity rates in developed countries are primarily due to increased calorie intake, not decreased physical activity.
Published in the journal PNAS, the study analyzed over 4,200 adults aged 18 to 60 from 34 populations across six continents, including hunter-gatherers, farmers, and people in industrialized nations.
Lead researcher Herman Pontzer, professor of evolutionary anthropology at Duke, explained that people in wealthier countries actually burn the same or even more energy daily compared to those in less industrialized settings.
‘Despite decades of trying to understand the root causes of the obesity crisis, it’s clear that changes in diet—not reduced activity—are the main cause of obesity in the U.S. and other developed countries,’ Pontzer said.
The research team used the UN Human Development Index to assess economic development and found only a slight decline in size-adjusted total energy expenditure with industrialization.
These changes, however, accounted for just a small portion of the rise in body fat, suggesting that dietary changes are the true culprits. Amanda McGrosky, lead investigator and assistant professor at Elon University, stated, ‘Differences in energy expenditure explained only a fraction of the increase in body fat that accompanied development.’
The study emphasizes that while physical activity remains essential for health, it should be seen as complementary to diet, not a replacement.
Future research will focus on identifying which specific dietary factors in developed nations are driving obesity. The authors hope their findings will refine public health strategies and encourage balanced approaches that target both diet and exercise.
If you care about obesity, please read studies about Scientists find new key cause of obesity and findings of Double whammy: diabetes drug also knocks out obesity.
For more about weight loss, please read studies about Scientists find secrets to long-term weight loss success and findings of Weight loss surgery linked to this mental disease.
The study is published in PNAS.
Copyright © 2025 Knowridge Science Report. All rights reserved.
