Trends in Body Mass Index in Developing Countries

Abstract

The purpose of this study was to examine the extent to which adult body mass index (BMI) has changed in developing countries over the past several decades. The analysis is based on a compilation and analysis of mean BMI in 1,432 published samples from developing countries measured between 1957 and 1994. A hierarchical multiple-regression model is applied to these data, controlling for country and study as random covariates and modelling age, sex, socio-economic status, and year as fixed effects. The results reveal a statistically significant increase in mean BMI between 1957 and 1994 in all major regions of the developing world. The size of the increase was 1.4 kg/m2 over the 37-year period, with a 95% confidence interval of 0.4 to 2.4 kg/m2. Mean BMI appears to have increased in all major regions of the developing world, although the size of the increase varies across regions. Using assumptions about the statistical distribution of BMI within populations and cut-off points recommended by the World Health Organization, the analysis suggests that the increase in mean BMI may have resulted in a slight decrease in the prevalence of underweight (BMI<18.5 kg/m2) but is unlikely to have produced an increase in obesity (BMI>30 kg/m2) in most regions. By contrast, the use of lower cut-off points to define obesity, as is done in many individual studies, would suggest that obesity has increased in developing countries. These results highlight the importance of using standardized definitions for underweight and obesity among adults, the need to assess and consider the prevalence of both conditions simultaneously during planning and policy development, and the need to identify policy instruments appropriate to the nutritional profile within a country.