Cohort trends in duration of obesity in the United States, 1925-89: Estimates from cross-sectional data.

This paper introduces the metric 'mean duration of obesity' to measure the average number of years lived with obesity in a population. A procedure was developed to estimate duration from periodic cross-sectional surveys. For annual cohorts born in the United States between 1925 and 1989, I estimated a logit model to derive age-cohort-specific probabilities of overweight and obesity (body mass index 25 to <30 and [Formula: see text]30, respectively), and applied life table techniques to convert these into person-years. Duration of obesity by age 50 increased fourfold from 3.58 to 14.35 years. The rate of increase was stronger across the 1945-79 and 1980-89 cohorts than the 1925-44 cohorts. The trend was driven by increased risks of obesity among children: age groups under 20 were responsible for 31 per cent of the duration increase between the 1930 and 1960 cohorts, but 72 per cent between the 1960 and 1985 cohorts.