The popular belief that the main cause of obesity is insufficient physical activity has undergone a serious revision. An international research team led by Amanda McGroskey from Duke University (USA) has established that the key factor in the global increase in body weight is not physical inactivity, but the consumption of high-calorie, ultra-processed foods.
The study, published in the prestigious scientific journal PNAS , looked at more than 4,200 people from 34 different populations on six continents — from hunter-gatherer tribes to urban dwellers — and looked at measures such as total and basal energy expenditure, body mass index, and body fat levels.
At first glance, the data seemed to confirm the conventional wisdom: people in economically developed countries had higher body mass and fat levels. However, after adjusting for age, gender, and body type, it turned out that they were no less, if not more, physically active than people in traditional societies.
Total energy expenditure has almost no impact on obesity risk—only 10% of the time does it correlate with fat accumulation. This result refutes the popular idea that “the gym is everything.”.
Instead, experts say the real cause is the overconsumption of ultra-processed foods—foods rich in sugar, salt, fats, flavorings, and other flavor enhancers. Such foods disrupt natural satiety signals, leading to chronic overeating. In addition, technological processing makes food easily digestible and energy-dense, which makes excess calories easily accumulated.
“ Modern food alters our appetites, works against satiety signals, and promotes obesity even with normal levels of physical activity ,” the study authors note.
Physical activity, despite its benefits for the heart, blood vessels, psyche, and metabolism, is not capable of curbing the obesity epidemic on its own if people continue to eat fast food, carbonated drinks, and convenience foods.
Researchers call on governments and society to:
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regulate the sale of sugary drinks;
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to label the degree of processing of products;
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limit advertising of unhealthy food;
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ensure access to natural food, especially for vulnerable populations.
The problem of obesity is not only a sedentary lifestyle, but also an aggressive food industry that forces us to eat more than we need. To effectively combat the epidemic of excess weight, it is necessary to change not only habits, but also the food system itself.
