Descriptive statistics on changes in ED diagnostic status from T1 to T2 appear in Table 1. At T1, 4% of the sample (n=101) met DSM-5 criteria for an ED. At 4-year follow-up/T2, 3.3% of the sample (n=83) met DSM-5 criteria for an ED, with 48.2% (n=40) of these cases representing new onset EDs, and 51.8% (n=43) of these cases representing men who had maintained an ED from baseline to 4-year follow-up).

As shown in Table 2, the MANOVA indicated differences on all T1/baseline putative factors across the four groups of participants classified based on the presence or absence of an ED at each wave of assessment, with subsequent post-hoc tests revealing that the groups differed significantly from each other in mean baseline scores of all putative factors. The significant differences between groups that were equivalent in terms of presence or absence of an ED at baseline/T1 but showing different outcomes at follow-up/T2 were of interest. Specifically, the “onset” group (i.e., without an ED at T1 and with an ED at T2) reported greater baseline scores on all putative factors as compared to the “stable no-ED”, or onset-free, group (i.e., without an ED at both time points). Likewise the “maintenance” group (with an ED at both time points) reported greater baseline scores on all putative factors as compared to the “cessation” group (i.e., with an ED at T1 and without an ED at T2).

Odds ratios (ORs) from individual predictor models for associations of predictors with T2 “onset” (v. onset-free) and “maintenance” (v. cessation) are shown in Table 3. Amongst individuals without an ED at baseline/T1 assessment, higher levels of self-objectification, body dissatisfaction, appearance-ideal internalization, dieting, and negative affectivity at T1 were significantly associated with the “onset” of an ED at T2/follow-up. Amongst those with an ED at T1, higher levels of self-objectification, body dissatisfaction, appearance-ideal internalization, dieting, and negative affectivity at T1 were significantly associated with ED “maintenance” at T2/follow-up. Changes in all individual predictor variables between assessments (i.e., from T1 to T2) were also significantly associated with both the “onset” and “maintenance” of an ED at T2/follow-up; ORs were comparable in magnitude to those for the individual predictor values at T1 (Table 3). Importantly, we also confirmed significant findings when restricting analyses to those for whom ED diagnosis was checked/confirmed by the clinical interview in the case-control design.1

Examination of max-rescaled R2 values, also reported in Table 3, indicated that the individual predictor model with the greatest explanatory/predictive value in explaining either “onset” (R2=.41) or “maintenance” (R2=.40) ED was the self-objectification model. In each individual predictor model, the remaining predictors (body dissatisfaction, appearance-ideal internalization, dieting, negative affectivity) had only half (or less) of the explanatory strength for either “onset” or “maintenance” ED. The explanatory value of the combined model, including all statistically significant individual predictors and adjusted variables/covariates (BMI and disordered eating levels at study entry, and changes in BMI between assessments) entered, was high (R2=.68 for onset, .67 for maintenance); the only covariates explained 10% and 11% of the variance in the “onset” and “maintenance ED, respectively.

Using longitudinal data we examined the influence of relevant factors in predicting the onset and maintenance of men's (DSM-5) EDs at 4-year follow-up. Our findings showed that elevated self-objectification, body dissatisfaction, appearance-ideal internalization, dieting, and negative affectivity at baseline as well as changes in these factors between assessments were significantly associated with future ED onset. Interestingly, greater initial levels in the aforementioned five factors as well as changes in these factors between assessments also predicted ED maintenance, with ORs comparable to those for individual predictor variables contributing to the ED onset (Table 3). However, examination of the variance explained by each of the examined factors indicates that men's self-objectification tendency emerged as the strongest predictor of both ED onset and maintenance.

Our findings regarding body dissatisfaction, appearance-ideal internalization, dieting, and negative affectivity converged with those found in prior studies investigating their role on ED onset amongst adolescent girls (e.g., Culbert et al., 2015; Stice et al., 2011) and on the development and persistence of college women's clinically significant ED pathology (e.g., Dakanalis, Timko et al., 2016). This implies that the effects of these variables are moderately robust and potentially not gender specific. The findings regarding self-objectification are novel and should inform preventive and treatment research. Hyper-focused attention on, and constant monitoring of, the body's appearance (characterizing self-objectification) has been consistently found to be an outcome of the appearance-ideal internalization in both sexes (Tiggemann, 2013). It has also been found to magnify the discrepancy between actual and ideal body attributes and/or perceived body imperfections (Hausenblas et al., 2013; Riva et al., 2015). Thus, self-objectification and its cumulative effect may play a key role in the acceleration of body dissatisfaction, associated affective distress and/or dieting attempts, thereby potentiating meaningful increases in the risk of ED pathology (Dakanalis, Carrà, Timko et al., 2015; Fitzsimmons-Craft et al., 2011). Although support for this suggestion came from a recent study that followed (initially) asymptomatic adolescents of both sexes for four years (Dakanalis, Carrà, Calogero et al., 2015), self-objectification might also be involved in the maintenance process of ED pathology (Tiggemann, 2013). According to ED scholars, when patients with any ED continue to think and monitor their own body “from a third-person perspective, factors that contribute significantly to EDs (i.e., body dissatisfaction, dieting, negative affectivity) remain untouched” (Fitzsimmons-Craft et al., 2011, p. 303). Research needs to validate this process and clarify the temporal sequence of the potential intervening experiences linking self-objectification to both the onset and persistence of ED pathology (Riva et al., 2015).

Even with longitudinal data and statistical control of several factors, unmeasured third variables (i.e., genetic factors) could account for the relationships observed (Culbert et al., 2015). The prevalence estimates of any DSM-5 EDs obtained in our sample at baseline/T1 (4%) and 4-year follow-up/T2 (3.3%) are consistent with those reported in comparable community surveys of young adult men (Holland et al., 2013) and the existing literature on the general population of college-aged men (Dakanalis & Riva, 2013a; Raevuori et al., 2014). The sample size of symptomatic and asymptomatic participants was also appropriate (i.e., above the recommended 10:1 cases-to-variable ratio, Allison, 2012) for individual and combined logistic regression models conducted for examining the impact of each predictor and all five predictors on “onset” and “maintenance” of any ED (Table 3), respectively. Yet the prevalence of specific DSM-5 ED diagnoses (Table 1) was too low to allow examination of associations of putative factors with specific threshold ED and OSFED entities. Although considerably larger prospective studies will be necessary to address this issue, it is worth noting that prior research supports the “trans-diagnostic” relevance of the variables considered in this study (e.g., Culbert et al., 2015; Dakanalis, Timko, Clerici et al., 2015; Fitzsimmons-Craft et al., 2011; Stice et al., 2011; Tiggemann, 2013). Additional descriptive data (not shown) indicating that none of T1 or T2 symptomatic participants reported receiving ED treatment before the T1 and between T1 and T2 assessments may suggest that our findings reflect a naturalistic progression of EDs and the vulnerability factors considered in this study. Despite evidence that the presentation format of measures (paper-and-pencil vs. online) did not change the quality of results (e.g., Dakanalis, Timko, Madeddu et al., 2015), all study variables embedded in online surveys were based on self-report data that is potentially susceptible to self-deceptive responding and assessment error (in the case of survey-based diagnoses). Importantly, survey-based diagnoses demonstrated concurrent validity with interview-based ED diagnoses in our sample, increasing confidence in the reported results. Moreover, we could confirm significant findings also when restricting analyses to those for whom ED diagnosis was checked/confirmed by the clinical interview in the case-control design. Although our analytic sample was representative (as mentioned in methods), men in the current study came from a selective northern Italian university; thus findings may not generalize to populations of dissimilar demographics, including inpatient samples. However, few available studies also involving men, and examining the stability of ED diagnoses in both community-based (Holland et al., 2013) and inpatient (Keel & Brown, 2010) samples reported rates of remission (57-58%) quite close to those observed in this study (57.4%, i.e., 58 of 101 men with an ED at T1 did not retain diagnosis at T2), thereby supporting the representativeness of longitudinal patterns observed in our sample. Additionally, although the duration between T1 and T2 assessment (4 years) was a strength of our study, we were not able to examine potential fluctuations or changes in ED status over the course of illness (i.e., between T1 and T2), and the examined factors may have demonstrated important associations with remission and relapse that we were unable to evaluate. In addition, future research should also test for interactions between the examined factors suggestive of qualitatively distinct risk/maintenance pathways (Dakanalis & Riva, 2013a). This could benefit from, for example, classification tree analyses that are also able to empirically derive cut-points for continuous measures (such as those used in this study for assessing the putative factors) and allowing optimal identification of young adult men at elevated risk for the onset and maintenance of DSM-5 EDs (Stice et al., 2011).

Despite the aforementioned limitations, our findings revealing that self-objectification, body dissatisfaction, appearance-ideal internalization, dieting, and negative affectivity were all predictors of both ED onset and maintenance highlight potentially similar psychological foci for prevention and treatment efforts. Importantly, self-objectification had greater explanatory value with regard to both ED onset and maintenance, as compared to the remaining four traditionally accepted risk/maintenance factors (Culbert et al., 2015). Thus, a focus on reducing self-objectification might be considered as a potential intervention strategy to prevent and treat young men's ED pathology. Indeed, recent research revealed that the addition of self-objectification as a target variable within traditional (evidenced-based) cognitive dissonance prevention programmes targeting appearance-ideal internalization, increased the reduction of undergraduate eating and body-related disturbances as well as the small-to medium effect sizes of these traditional programmes (Culbert et al., 2015). The leading empirically supported cognitive-behaviour (CB) treatment for BN, which has been successfully adapted with the goal of making it “trans-diagnostic” appears “more effective in reducing ED behavioural symptoms rather than producing changes in body image disturbance” (Dakanalis, Carrà, Timko et al., 2015, p.102). Hence, the use of CB or other interventions of proven efficacy in combination with promising approaches (i.e., virtual reality) designed to decrease the hyper-focus on, and scrutiny of, body appearance (characterizing self-objectification), and to address body dissatisfaction and negative reactions to one's image, might be helpful to decrease ED pathology and improve treatment outcomes (Dakanalis, Carrà, Calogero, Fida et al., 2015; Dakanalis, Carrà, Calogero, Zanetti et al., 2015; Dakanalis et al., 2014; Riva, Gaggioli, & Dakanalis, 2013; Riva et al., 2015).

The work was supported by a grant from the Onassis Foundation (O/RG 2010/G/A212). The authors report no declarations of financial interest.