Healthy Weight 2
participants showed significantly lower eating disorder symptoms at 1- and 2-yr follow-up, which is encouraging because only two prevention programs have produced effects for this outcome that persist through multiple-yr follow-ups (Stice et al., 2008
). That this intervention was only 4 hours in duration makes this effect even more striking. The effect size was relatively small (d
=−.26) and reliable change score analyses were only partially significant, though this effect was twice as large as the average effect size for reductions in eating disorder symptoms from eating disorder prevention trials with 1- and/or -2 yr follow-up assessments (d
This finding echoes the significant reduction in eating disorder symptoms observed at 3-yr follow-up for the original Healthy Weight
intervention (Stice et al., 2008
). Theoretically, the intervention helped participants develop healthier weight control strategies, which reduced reliance on transient dieting and other unhealthy weight control behaviors that characterize eating disorders. More importantly, Healthy Weight 2
participants showed a 60% reduction in eating disorder onset over the 2-yr follow-up, which was a clinically significant difference that represented a large effect (HR = 2.2). This effect replicated the 60% reduction in eating disorder onset observed for the original Healthy Weight
prevention program (Stice et al., 2008
). This finding is novel, because only the original Healthy Weight
prevention program and the dissonance-based Body Project
have significantly reduced onset of blinded interview-assessed eating disorders over a multiyear follow-up.8
Healthy Weight 2
participants showed significantly lower BMI at 6-mo follow-up, but this effect was not significant at either 1- and 2-yr follow-up and this intervention did not reduce obesity onset. It was encouraging that this prevention program produced effects for both eating disorder symptoms and BMI, as only two prevention programs have produced intervention effects for both of these outcomes (Stice et al., 2008
), though a treatment intervention for overweight individuals who reported binge eating produced significantly greater weight loss for intervention versus control participants and may have reduced objective and subjective binge eating in intervention participants9
(Jones et al., 2008
). However, the fact that the original 3-hour Healthy Weight
intervention produced larger and more persisting effects for BMI and risk for obesity onset (Stice et al., 2008
) implies that adding principles to facilitate healthy dietary and exercise changes, largely drawn from nutrition science, attenuated intervention effects. The lack of such explicit guidelines in the original Healthy Weight
intervention may have put more of the onus for change on participants, increasing personal investment and motivation to maintain the selected dietary and exercise changes. The inclusion of the dietary principles may also have complicated the simple message of the original intervention, which was that making small, lasting, incremental healthy changes to dietary intake and activity level could foster healthy weight control. This interpretation suggests that it might be useful to attempt to replicate the intervention effects on both eating disorder symptoms and BMI that were observed for the simpler original Healthy Weight
In terms of secondary outcomes, the Healthy Weight 2 intervention produced significantly lower body dissatisfaction through 1- and 2-yr follow-ups, echoing effects from the original Healthy Weight intervention that persisted through 1-, 2-, and 3-yr follow-ups. Perhaps the focus on the healthy-ideal versus the thin-ideal promoted body satisfaction. Attempting to make positive lifestyle changes may also improve body satisfaction. However, the effects for body dissatisfaction were relatively small and the reliable change score analyses produced mixed support in this trial, and there were no long-term intervention effects on depressive symptoms, dieting, caloric intake, and physical activity. Presumably, the lack of effects for caloric intake and physical activity explain the absence of a longer-term effect on BMI.
Moderator analyses revealed that the effects on eating disorder symptoms at 1- and 2-yr follow-up were significantly larger for participants with initial elevations in eating disorder symptoms, extending results observed in the report focusing on the acute effects, which observed similarly stronger intervention effects at 6-mo follow-up (Stice et al., 2012
). Presumably this is because the participants with elevated eating disorder symptoms scores at pretest had a greater opportunity to show reductions in this outcome. Moderator analyses also revealed that intervention effects on eating disorder symptoms varied as a function of pretest perceived pressure to be thin. As hypothesized, the intervention produced stronger effects over long-term follow-up for participants who reported lower versus higher pretest pressure to be thin. However, the fact that this effect was reversed at posttest suggests that it might be best to focus on the subgroups that showed stronger intervention effects identified by the other moderators. Last, moderator analyses showed that the Healthy Weight 2
intervention produced significantly lower BMI at 6-mo, 1-yr, and 2-yr follow-up for participants with pretest elevations in both eating disorder symptoms and BMI. These results are encouraging given the difficulty of obesity prevention and extend the evidence from the report focusing on the acute effects (Stice et al., 2012
) in suggesting that the Healthy Weight 2
intervention does significantly reduce BMI for participants with eating disordered behaviors. Presumably by reducing disordered eating behaviors (e.g., binge eating) participants are at a reduced risk for unhealthy weight gain. The evidence that the intervention also produced lower BMI for those with the highest initial BMI implies the intervention reduced excessive weight gain for those at greatest risk for future weight gain by virtue of initially elevated adiposity. These results, and those from the acute effects report, imply an intriguing interplay between eating disorder symptoms and unhealthy weight gain in young women with body image concerns. Collectively, the moderation effects suggest that it might be prudent to target young women who report a confluence of body image concerns, disordered eating behavior, and elevated initial BMI in future selective prevention trials that seek to reduce risk for both eating disorders and obesity.
Regarding limitations, the sample included college students who were largely White, suggesting that care should be taken in generalizing the results to more ethnically and educationally diverse populations that also suffer from eating disorders and obesity. The sample consisted solely of young women, implying that results should not be generalized to young men. Also, because self-report measures of dietary intake and physical activity are biased, it would have been preferable if objective measures of these outcomes had been used.
Results suggest that there may be value in refining this intervention to produce larger effects, such as by incorporating dissonance-induction procedures to promote greater reductions in energy dense food intake and greater increases in physical activity, though they also suggest it might be valuable to attempt to replicate the effects of the simpler Healthy Weight
prevention program. The present findings also imply that it might be advantageous to target young women who have initial elevations in disordered eating behaviors and BMI in what might be best construed as indicated prevention programs (e.g., Jones et al., 2008
). Given that both eating disorders and obesity are very prevalent, yet resistant to treatment, it will be vital to develop and disseminate prevention programs that effectively reduce these two major public health problems.