Sex differences in the pattern of age-dependent increase in the BMI from 20-59 years

This study tested the hypothesis of a linear increase of the BMI with age among adults. Materials comprised 32,762 occupationally active females and males 23-59 years age resident in Wroclaw, southwestern Poland. All subjects were medically examined in the course of health screening. The BMI increases linearly with age in women, but increases with age in men in two stages--a more intensive rise between 20-40 years and much slower increase between 40-60 years. This hypothesis was verified with a linear regression model in women but for men piecewise regression with a break at 40 years of age fits the age trends.