Increased calorie intake, especially from ultra-processed foods, is the primary driver of obesity in economically developed populations, overshadowing the impacts of reduced physical activity. Digest
Obesity has risen sharply with economic development, but what's driving it—eating more or moving less—has been difficult to disentangle. Both overeating and reduced physical activity have been blamed, but their relative contributions remain a matter of debate. A recent study found that increased calorie intake, especially from ultra-processed foods, is far more strongly linked to obesity than low activity.
The study involved more than 4,200 adults from diverse populations across six continents, including hunter-gatherers, pastoralists, farmers, and those living in industrialized countries. Researchers measured participants' daily energy expenditure, resting metabolic rate, and physical activity. They also assessed body mass index and body fat percentage and estimated calorie intake and diet quality where possible.
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People in more economically developed populations had more body fat, higher body mass, and higher body mass index. They also burned more energy overall, primarily because they were larger. After adjusting for body size, both total and basal energy expenditure declined by 6% to 11% as economic development increased, explaining only about 10% of the rise in body fat and body mass index. In contrast, people in wealthier populations ate more calories, and those who consumed more ultra-processed food had higher body fat.
These findings suggest that increased calorie intake—more than reduced physical activity—is the primary force behind obesity linked to economic development. Learn more about the effects of ultra-processed foods on body weight in this episode featuring Dr. Rhonda Patrick.