Energy expenditure and physical activity level are not higher in developing countries compared to industrialized

Do people in developing countries have higher total energy expenditures and physical activity levels than industrialized countries?  Most of us would assume so, but a new study adds to existing research suggesting otherwise.

Dugas et al. performed a meta-analysis on studies that measured total energy expenditure and physical activity level (ratio of total energy expenditure to resting energy expenditure) in adults.  Importantly, they only included studies that used doubly labeled water, the gold standard method for measuring energy expenditure.  In total, they included 98 studies that covered 4,972 men and women.  14 of these studies (483 people) were of low to middle income countries.  The classification of country development (low to middle or high) was based on the human development index (HDI) by the United Nations Development Program or if the countries were members of the Organization for Economic and Community Development.

Countries covered:

Low/middle HDI: Bolivia, Cameroon, China, Gamiba, Guatemala, India, Jamaica, Nigeria, Russia, South Africa, Swaziland.

High HDI: European countries, United States, Canada, Mexico, Cuba, Chile, Brazil, Japan, Australia, New Zealand.

For those who like to see the numbers:

As you can see, average body weight was much lower in the low or middle HDI group compared to high HDI group for both men (66.1 kg vs 81.3 kg) and women (59.3 kg vs 72.6 kg).  Total energy expenditure was also lower for both men and women in the low or middle HDI group compared to the high HDI group, though this was unadjusted for body size and weight.  When adjusted for age and body weight, energy expenditure was not different between the groups. A small inverse association of energy expenditure in the studies based on the year of publication in men but not women suggests that total energy expenditure may have decreased slightly between 1989 and 2009.  Note however: this study by Westerterp and Speakman found that between 1988 and 2006 physical activity energy expenditure actually slightly increased in industrialized countries and physical activity level was stable.

Physical activity level (which according to the authors is “modestly adjusted for body size” because it includes resting energy expenditure) was higher in the low or middle HDI men but lower in the low or middle HDI women.  However when adjusted for age and body weight, physical activity level did not differ between the groups.

The authors make quite a case against a relationship between energy expenditure and obesity by citing other research that also suggests energy intake, not expenditure seems to be the influential factor on the obesity pandemic.

Apparently early reviews utilized studies that used questionnaires and physical activity diaries or recalls (which are much more prone to false results), as the doubly labeled water method was not invented until the 1980’s thus not many studies utilized this technique.  This may partly explain why people hold the assumption that activity level is dramatically lower in developed countries.  However, according to this new paper and others of recent, energy expenditure has not decreased in the last ~2.5 decades in developed countries, and compared to lesser developed countries, is not significantly different overall either. It should be noted that at the individual level, increasing activity level can certainly be beneficial, especially in a Western food environment.

Reference

Dugas LR, Harders R, Merrill S, Ebersole K, Shoham DA, Rush EC, Assah FK, Forrester T, Durazo-Arvizu RA, & Luke A (2011). Energy expenditure in adults living in developing compared with industrialized countries: a meta-analysis of doubly labeled water studies. The American journal of clinical nutrition, 93 (2), 427-41 PMID: 21159791