Overweight and obesity between adolescence and young adulthood: a 10-year prospective cohort study.

Objectives: To assess changes in overweight and obesity between adolescence and young adulthood.

Design: Prospective 8-wave cohort study in Victoria, Australia, with 1,520 adolescents tracked from the age of 14 for a period of 10 years.

Main Outcome Measures: Participants aged <18 years were classified as non-overweight, overweight, or obese according to International Obesity Taskforce cutoff points. In those aged >18 years overweight was defined as a body mass index (BMI) ≥ 25; and obesity as a BMI ≥ 30.

Results: The proportion of overweight individuals increased from 20% in mid-adolescence to 33% at the age of 24 years. Obesity increased from 3.6% to 6.7%. Approximately 40% of young adults with a BMI ≥ 25 had been persistently at normal weights during adolescence and approximately 80% had been at a normal weight at some point. Around half of obese young adults had never been classified as obese as adolescents. No individual with persistent obesity in adolescence had a BMI <25 at 24 years. A total of 31% of females and 59% of males who had been overweight for only one or two waves of adolescent data collection had a BMI ≥ 25 at 24 years.

Conclusions: Substantial shifts in overweight and obesity occur between adolescence and young adulthood; the extent of continuity depends on both the severity and persistence of adiposity in adolescence. Few adolescents who peak into obesity or are persistently overweight achieve a normal weight in young adulthood. Resolution is more common in those who are less persistently overweight as teenagers, suggesting scope for lifestyle interventions in this subgroup.