An estimated 1.25 million people in the UK have an eating disorder (Beat, 2023a). This includes anorexia nervosa (AN), bulimia nervosa (BN), binge eating disorder (BED) and purging disorder (PD), which are associated with numerous negative outcomes, including suicidality, unhealthy body weight, distress, functional impairment, and mental health service utilisation (Allen et al., 2013; Stice et al., 2013). Despite this, most people with an eating disorder do not receive treatment (Swanson et al., 2011), making prevention a public health priority. To do this, we need evidence-based prevention programmes which can prevent the onset of eating disorder symptoms before treatment is needed.
The Body Project is a prevention programme which aims to reduce the pursuit of the thin ideal among people who are at a high risk of developing an eating disorder. The thin ideal refers to the desire to possess a thin body type (Ralph-Nearman & Filik, 2020), the pursuit of which has been found to predict the future onset of BN, BED, and PD (Stice et al., 2017). However, research has not yet established whether the Body Project can prevent the onset of different types of eating disorders, with evidence suggesting that it might not be effective in preventing AN onset (Stice et al., 2023). Therefore, D’Adamo and colleagues (2023) combined data from three randomised controlled trials (RCTs) to assess whether peer-led versions of the Body Project were able to prevent the onset of these four different types of eating disorders.
The authors combined data from three previous studies (Ghaderi et al., 2020; Stice et al., 2008, 2020). Each of these studies was an RCT comparing the Body Project (n = 339 participants) to a control condition (n = 753 participants). Studies were conducted in the USA (Stice et al., 2008, 2020) and Sweden (Ghaderi et al., 2020).
Studies recruited either female high school and/or college students using a range of methods (e.g., flyers, online advertisements). Participants were included if they had body image concerns and were excluded if they had a current eating disorder (restricted to AN or BN in Stice et al., 2008, 2020 due to DSM-IV criteria) or if they had severe depression, suicidality, or another serious psychiatric condition (Ghaderi et al., 2020).
Intervention & control conditions
All participants were randomised to either the Body Project intervention or a control condition. The Body Project conditions consisted of weekly 1-hour sessions either in-person or online, and were led by either peer educators (Stice et al., 2020), the study authors/graduate students (Stice et al., 2008), or undergraduate students (Ghaderi et al., 2020).
Control groups consisted of an education brochure (Stice et al., 2008), a documentary (Stice et al., 2020), or an expressive writing exercise (Ghaderi et al., 2020).
Diagnostic interviews were conducted at baseline, post-intervention, and 6-monthly or yearly intervals for up to 24 months (Ghaderi et al., 2020), 36-months (Stice et al., 2008), or 48-months (Stice et al., 2020). Studies by Stice et al. (2008) used the semi-structured Eating Disorder Diagnostic Interview to assess eating disorder symptoms, and Ghaderi et al. (2020) used the Eating Disorder Examination, which was conducted over the phone. Other outcomes were measured, including purging behaviours and excessive exercise.
Logistic regression models were used to test whether the onset of both subthreshold and threshold eating disorder symptoms were lower in the intervention compared to the control conditions throughout the follow-up periods. Separate models were estimated for AN, BN, BED, and PD.
The combined participant group (N = 1,092) was on average 19.3 years old (range 14-64 years). Some differences at baseline were identified within the intervention and control groups, but further analyses supported combining in-person and virtual intervention groups, and all of the control groups.
Regarding the onset of specific eating disorders, the study found:
- For Body Project participants without an eating disorder at baseline, the onset of any eating disorder during the follow-up period was 10.6% (n = 36; AN = 3, BN = 10, BED = 16, PD = 7).
- For control condition participants without an eating disorder at baseline, the onset of any eating disorder during the follow-up period was 17.4% (n = 131; AN = 9, BN = 42, BED = 39, PD = 41).
- Reductions in symptoms for those in the Body Project group compared to the control groups were 62% (PD), 46% (BN), 25% (AN), and 8% (BED).
- The reduction in the onset of threshold or subthreshold symptoms of BN (OR = 0.47, p = .02) and PD (OR = 0.35, p = .009) were found to be statistically significant in the Body Project participants compared to those in the control group. This was not the case for AN (OR = 0.56, p = .213) or BED (OR = 0.70, p = .149).
The results of this study indicate that the Body Project may not be suitable for all eating disorder types. A significant reduction in eating disorder onset was observed for BN and PD, where peer-led Body Project groups produced a 46% and 62% reduction in symptom onset respectively. Whilst this has critical prevention effects, the same reductions were not seen for AN and BED, meaning alternative preventative strategies may need to be considered for those at risk of developing these eating disorders.
Strengths and limitations
This study has various strengths:
- By combining three separate trials together, the external validity of the results may be improved due to a more varied sample being tested within multiple populations and settings.
- Follow-up times were extensive, ranging from 24-months to 48-months across the three studies. Given that the population of these studies were those without eating disorders, sufficient follow-up times would be needed to allow enough time for eating disorder onset.
However, limitations of this study include:
- The combination of separate studies with different control groups and follow-up lengths increases variability and may have reduced the statistical power of this study. However, the fact that these studies share other methodological similarities in their population, recruitment methods, and intervention also mean that the result of this paper should not be discounted.
- The use of control groups which were so different to the intervention may mean that the positive effect of the Body Project may be down to non-specific treatment effects, such as the interaction with peers as part of the intervention. Future studies may instead consider alternative control conditions, such as wait-list control groups, to be able to determine the impact of the intervention without other peer influence.
- Only the studies by Stice et al. (2008, 2020) collected data on ethnicity, whereby 66% of the sample were White. This means we are unable to know the true variation of the combined sample, which was already limited to the inclusion of only females, meaning that results cannot be generalised to males or any other identifying persons. Research suggests that approximately 25% of those with eating disorders are male (Beat, 2023b), highlighting the importance of considering males in eating disorder research.
Implications for practice
The results of the current paper indicate that the Body Project may be effective for those with BN (bulimia nervosa) and PD (purging disorder). This is an important finding, given that <50% of people with these disorders achieve full recovery (Forney et al., 2021). This highlights the need for effective preventative interventions to reduce the incidence of these disorders and the number of people requiring acute treatment; however, given the amounting pressure on services to provide treatment to those in acute need (Beat, 2023c), the provision of preventative interventions to those without symptoms seems unlikely. Implementation of preventative interventions in schools and universities to target those at risk should be considered, alongside further research conducted with more active control groups, to determine whether the intervention remains effective and what the specific effects are.
Despite these promising results, the fact that the Body Project did not appear effective for AN (anorexia nervosa) and BED (binge eating disorder) highlights the need for further research to target transdiagnostic risk factors which predict all four eating disorders. Research indicates that the over-evaluation of weight and shape and fear of weight gain may be predictors of all four eating disorder types (Stice et al., 2021). The authors of this paper suggest developing a refined version of the Body Project in an attempt to target these shared risk factors which have yet to be targeted within a prevention programme.
Given the homogenous sample tested in the three studies reported in this paper, more research is also now needed to test whether the Body Project is effective across gender, ethnicity, and socio-economic class. This is especially important given that the prevalence of body dissatisfaction has increased the most in boys in recent years (Solmi et al., 2021), and the recent finding that those who identify with more than one racial group have higher prevalence of eating disorder pathology compared to those who have a monoracial identity (read more in Andie’s Mental Elf blog here). Research such as this highlights the need for effective preventative interventions for a range of populations.
Statement of interests
D’Adamo, L., Ghaderi, A., Rohde, P., Gau, J. M., Shaw, H., & Stice, E. (2023). Evaluating whether a peer-led dissonance-based eating disorder prevention program prevents onset of each eating disorder type. Psychological Medicine, 1–8.
Ashdown, A. (2022). Unique multiracial identities may serve as a protective or risk factor for eating disorders. The Mental Elf.
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