Obesity Crisis: Processed Foods Trump Exercise, New Study Reveals

Research challenges decades-old assumptions about weight gain

A major international study suggests that the global rise in obesity is driven more by increased consumption of ultra-processed foods than by a decline in physical activity. The findings, which analyzed data from over 4,000 individuals across 34 diverse populations, indicate a need for a significant shift in public health strategies.

Rethinking the Obesity Equation

For years, economic development was commonly linked to obesity through a reduction in people’s exercise levels. However, new research published in the *Proceedings of the National Academy of Sciences (PNAS)* directly contradicts this simplified view. The study, “Energy expenditure, obesity, and economic development across populations,” meticulously examined how economic progress influences energy expenditure and body composition.

Researchers, led by **Herman Pontzer** from Duke University and **Amanda McGrosky**, analyzed data from hunter-gatherer societies, pastoralists, farmers, and highly industrialized communities. They observed that as societies become more economically developed, individuals tend to have higher body mass, body mass index (BMI), and body fat. Counterintuitively, these same developed populations also showed greater overall energy expenditure, including basal and activity-related spending.

“Our findings challenge the simplistic notion that reduced energy expenditure is the primary driver of obesity in developed contexts. Instead, we found that people in more economically developed societies tend to expend more energy overall, yet they still experience higher rates of obesity, indicating other powerful factors are at play.”

—Herman Pontzer, Principal Investigator, Pontzer Lab

The Processed Food Factor

The study highlights that differences in total energy expenditure explained only a small portion of the increase in body fat associated with economic development. This points to other significant factors being at work.

“While we saw a marginal decrease 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. This suggests that other factors, such as dietary changes, are driving the increases in body fat that we see with increasing economic development.”

—Amanda McGrosky, Assistant Professor of Biology at Elon University

The research strongly implicates the proliferation of ultra-processed foods in driving obesity rates. Changes in food availability, accessibility, and composition appear to be more influential than previously emphasized.

Shifting Public Health Focus

The implications for tackling the global obesity epidemic are substantial. While maintaining physical activity is crucial for general health, the study emphasizes the urgent need for public health initiatives to prioritize dietary interventions.

Strategies aimed at combating obesity should focus on reducing the consumption of ultra-processed items and promoting healthier eating habits. For instance, a 2023 study found that individuals consuming more than 20% of their daily calories from ultra-processed foods had a 37% faster rate of overall mortality compared to those consuming less (JAMA Network Open).

The authors conclude that diet and physical activity should be viewed as essential and complementary components, rather than interchangeable elements, in addressing weight management.