Change of individual BMI in Switzerland and the USA: a multilevel model for growth

Abstract

The aim is to analyze and compare individual body mass index (BMI) growth patterns of adults from Switzerland and the US. The analyses are based on data from two population representative longitudinal household surveys, one from Switzerland, the other from the US. Each data set contains up to four data points for each adult individual. We use multilevel models for growth. It can be shown that growth patterns are different in different cohorts in the two countries: there are only small growth differences in the youngest and oldest, but large differences in the middle ages. The individual BMI increase of the middle-aged Swiss amounts to only half of that in the comparable US individuals. Given the much higher BMI level, especially in the youngest cohort, this points to severe obesity problems in the US middle-aged population in the near future. A positive correlation between individual BMI level and growth may emphasize this fact.