Increases In Average BMI Of Women In Low- And Middle-Income Countries Are Not Shared Equally Across The BMI Distribution
Overweight and obesity are on the rise worldwide and have become major public health threats in poor countries as well as affluent societies. A study published this week in PLOS Medicine by researchers from the University of Toronto and Harvard School of Public Health now shows that, even in low- and middle-income countries, as average body mass index (or BMI, an indicator of body fat) increases the rise is not shared equally across the BMI distribution with increased weight gain at the higher end of the BMI distribution and little change at low BMI values.
Analyzing changes in the BMI distribution between cross-sectional surveys conducted at different times in 37 low- and middle-income countries, Fahad Razak and colleagues found that as the average BMI in a population increases, the percentage of overweight and obese women are increasing at a much faster rate than decline in the percentage of underweight women. In surveys conducted in Ghana between 1993 and 2008, for example, the proportion of women aged 20-49 who were underweight only dropped from 10.2% to 8.7%, whereas the proportions of those overweight and obese more than doubled, rising from 11.8% to 23.5% and 3.9% to 9.7%, respectively. Compared to being normal weight, being overweight/obese or underweight is associated with much higher rates of death.
The authors conclude that “reliance on mean BMI or overweight/obesity to represent population level change does not capture the rapidly increasing BMI among high percentile segments of the BMI distribution and relative stagnation of body weight among low percentiles of the distribution”, and that “the mechanism driving the divergence patterns we observed is an important area for future research”.
Funding: No direct funding was received for this study. The authors were personally salaried by their institutions during the period of writing though no specific salary was set aside or given for the writing of this paper or were covered by grants for other research.
Competing interests: The authors have declared that no competing interests exist.
“Change in the Body Mass Index Distribution for Women: Analysis of Surveys from 37 Low- and Middle-Income Countries”, Razak F, Corsi DJ, Subramanian SV (2013)
PLoS Med 10(1): e1001367. doi:10.1371/journal.pmed.1001367