Overweight status and weight control behaviors in adolescents: Longitudinal and secular trends from 1999 to 2004

Background: This study examined 5-year longitudinal and secular trends in weight status and the use of healthy and unhealthy weight control behaviors in adolescents. Methods: Project EAT-II followed 2516 adolescents from Minnesota longitudinally from 1999 to 2004. The population included two cohorts allowing for the observation of transitions from early to middle adolescence (junior high school to high school) and from middle to late adolescence (high school to post-high school). Results: The prevalence of overweight (females: 28.7%; males: 28.0%) was high in early adolescence and remained high throughout adolescence. In females, between early and middle adolescence, there were steep longitudinal increases in the use of unhealthy weight control behaviors (48.6% to 58.8%, P = 0.001) and extreme weight control behaviors (9.4% to 17.9%, P < 0.001), and between middle and late adolescence, extreme weight control behaviors increased from 14.5% to 23.9% (P < 0.001). In males, extreme weight control behaviors doubled from middle to late adolescence (3.4% to 6.3%, P = 0.023). Use of diet pills doubled from 7.5% to 14.2% from 1999 to 2004 (P = 0.004) in high school females. One fifth (19.9%) of females in late adolescence reported taking diet pills. Conclusions: Overweight status and unhealthy weight control behaviors in adolescents are major public health concerns that warrant interventions addressing both problems.