Projection of US adult obesity trends based on individual BMI trajectories

Adult obesity has been increasing in the United States since the 1980s. For the cohorts now in young adulthood, the future prevalence of obesity depends on current prevalence and future increase in weight. In order to investigate the future of obesity, we pooled 92,615 body-mass index (BMI) measures from 26,337 adults interviewed and examined by the National Health and Nutrition Examination Survey (NHANES), aged between 25 and 55 in years 1998-2018. We applied functional data analysis to probabilistically reconstruct individual BMI trajectories. We found that the prevalence of obesity at age 55 is expected to reach 58% (95% uncertainty interval [UI], 54%-61%) for females born in 1984-1988 and 57% (95% UI, 53%-61%) for males born in the same cohort. The prevalence of severe obesity at age 55 will increase rapidly in both sexes. Time spent being obese will increase, e.g. for females from 10.7 years (95% UI, 10.4–10.9 years) in the 1964-68 cohort to 14.7 years (95% UI, 14.2-15.3 years) in the 1984-88 birth cohort. Although obesity prevalence may level off in the coming decades, higher prevalence of severe obesity as well as longer durations of obesity are therefore expected to increase the burden of this disease.