This large, cross-sectional study of adults from 34 populations across diverse economies finds that daily energy expenditure is actually greater in more developed populations. While body size-adjusted total and basal energy expenditure decreased slightly with economic development, this effect was small and did not explain the observed increase in obesity, suggesting that increased energy intake is likely the primary driver.

The authors declare no competing interests. The study received funding from various sources, including the US NSF and the Chinese Academy of Sciences, but these are not considered conflicts of interest related to the study's findings.

This study provides a valuable contribution to the understanding of obesity across different economies by using empirical data on energy expenditure and body composition from a diverse global sample. The large sample size, inclusion of various lifestyles and economies, and the use of objective measures are strengths. However, the cross-sectional design and the lack of detailed dietary data for most populations limit the ability to draw strong causal inferences. The study infers increased energy intake as the primary driver of obesity, which is plausible but not definitively proven. Overall, the study's methodology is robust, and the findings are significant, warranting a rating of 4 despite the mentioned limitations.