Life Survey (IFLS), we estimated changes in the mean and the variance of BMI over time
and across various socioeconomic groups based on education and households’ expenditure
per capita in 53,648 men and women aged 20-50 years. An increase in mean and standard
deviation was observed among men (by 4.3% and 25%, respectively) and women (by 7.3%
and 20%, respectively) over time. Quantile-Quantile plots showed that higher percentiles had
greater increases in BMI compared to the segment of the population at lower percentiles.
While between socioeconomic group differences decreased over time, within group
differences increased and were more prominent among individuals with poor education and
lower per capita expenditures. Population changes in BMI cannot be fully described by
average trends or single parameters such as the mean BMI. Moreover, greater increases in
within group dispersion compared with between-group differences imply that growing
inequalities are not merely driven by these socioeconomic factors at the population level.