According to Fahad Razak, the study’s lead author and a U of T clinical fellow working at St. Michael’s Hospital’s internal medicine unit, ‘One might think that as a country grows economically, the majority of the underweight population would move into the average BMI range, but our study shows the opposite: people of average weight are disappearing’.
‘This growing trend of body weight extremes is going to pose a major challenge for health care and policy leaders,’ Razak explained. ‘They will need to balance their priorities between addressing health issues afflicting the underweight who happen to be poor, and health issues afflicting the obese and overweight – the upper middle-class and rich.’
For the study, published as ‘Change in the Body Mass Index Distribution for Women: Analysis of Surveys from 37 Low- and Middle-Income Countries,’ in PLOS Medicine, the team
analysed the Body Mass Index (BMI) of 730,000 women living in 37 countries between 1991 and 2008. They discover that the numbers of overweight and obese women are increasing at a much faster rate than the decline in the number of underweight women, even as the average BMI in a population increases.
According to S V Subramanian, professor of Population Health and Geography at Harvard School of Public Health, the senior author of the study, ‘The study is novel because for the first time we are showing that increases in BMI are not happening equally across the board; rather increases in average BMI are largely driven by populations that are already overweight or obese, with little to no change among underweight individuals’.
Subramanian added that ‘This divergence in the population with fat getting fatter and lean remaining lean is aligned with general patterns of divergence on other domains such as income, and wealth, which of course, are primary drivers of weight status in these countries,’ and the team is planning to determine whether these patterns also hold true in more developed countries.