This study found that, in general, the prevalence of dieting and disordered eating behaviors was high and either remained constant or increased from adolescence to young adulthood. Of particular concern was the large increase in extreme weight control behaviors among youth transitioning from adolescence to young adulthood. Diet pill use more than tripled in most of the age and gender groups during the ten-year study period. Of concern, one-fifth of female young adults reported the use of extreme weight control behaviors. Furthermore, behaviors tended to track within individuals and, in general, participants who engaged in dieting and disordered eating behaviors during adolescence were at increased risk for these behaviors ten years later. Tracking was particularly consistent for the older females and males transitioning from middle adolescence to middle young adulthood. The tracking of these potentially harmful behaviors suggests that their use is not just “a phase” that adolescents go through, but instead indicate that early use of dieting and disordered eating behaviors may set the stage for continued use of these behaviors later on. Together the findings suggest a need for both early prevention efforts prior to the onset of behavioral patterns that tend to continue over time, as well as ongoing prevention and treatment interventions to address the high prevalence throughout adolescence and young adulthood.
Findings from the current study are generally in agreement with the available research that has examined population-based samples of males and females from adolescence through young adulthood, although there are some notable differences. Results from the current study showing gender differences in the course of disordered eating behaviors are in agreement with a prior 10-year longitudinal study conducted by Heatherton and colleagues among young people who were college students in 1982 (13
). Both studies showed dieting and disordered eating behaviors continue to be more prevalent among females than males as they transition through adolescence and young adulthood. In addition, both studies found evidence of increases in dieting among males as they age through their twenties. However, Heatherton et al found that dieting and disordered eating behaviors decreased among females transitioning to middle young adulthood, while in the current study, the prevalence of these behaviors either increased or remained constant over time. These differences might reflect the use of different measures, secular trends, or real differences between the two sample populations. Heatherton et al conducted their baseline analysis on college students in 1982, nearly 30 years ago, thus secular changes are certainly possible. Furthermore, the sample studied by Heatherton et al was drawn from a selective Northeastern college in the United States, and had much higher levels of dieting at baseline (75%) than the Project EAT population (50%). With regard to the tracking of behaviors, Kotler and colleagues examined longitudinal relationships between childhood, adolescent, and adulthood eating disorders over a 17-year interval (18
). Their study population differed from the Project EAT population in that participants were drawn from a rural area and were primarily white. Additionally, outcome measures differed across the studies. Nevertheless, findings from both studies are similar in showing that disordered eating behaviors tend to track between adolescence and adulthood.
Study strengths include the population-based nature of the sample, its large size, and its diversity in terms of gender, ethnicity/race and socio-economic status. Much of the previous longitudinal work examining the course of disordered eating or eating disorders have included samples that were either female (19
), primarily white (13
), or from higher socio-economic backgrounds (21
), limiting the generalizability of the findings. The long follow-up period, which captured major periods of transition is another study strength as few other studies have followed adolescents into middle young adulthood. Finally, the use of two age cohorts allowed for the capturing of slightly different stages of transition and for the replication of findings in different individuals. However, study limitations also need to be taken into account in interpreting the findings. Dieting and disordered eating behaviors were assessed with brief self-reported measures and frequency of use of behaviors was not assessed. The use of diet pills once during the past year, while of concern, is less of a concern than the weekly use of diet pills. Additionally, there was attrition from the original study population. For this reason, analyses only included individuals who were present at both EAT-I and EAT-III assessments and the population was weighted by non-response propensity so that the statistical results can be considered more representative of the original school-based sample.