Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight.

From 1985 to 2016, the prevalence of underweight decreased, and that of obesity andsevere obesity increased, in most regions, with significant variation in the magnitude of thesechanges across regions. We investigated how much change in mean body mass index (BMI)explains changes in the prevalence of underweight, obesity, and severe obesity in different regionsusing data from 2896 population-based studies with 187 million participants. Changes in theprevalence of underweight and total obesity, and to a lesser extent severe obesity, are largelydriven by shifts in the distribution of BMI, with smaller contributions from changes in the shape ofthe distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMIdistribution was left behind as the distribution shifted. There is a need for policies that address allforms of malnutrition by making healthy foods accessible and affordable, while restrictingunhealthy foods through fiscal and regulatory restrictions.