Compared to controls, participants in the treatment condition reported greater decreases in likelihood of future NSSI [Cohen's d (95% CI) = −0.38 (−0.90–0.15)], weight/shape concerns [−1.19 (−1.75 to −0.62)], depressive symptoms [−1.00 (−1.56 to −0.45)], and significant improvements in appearance [1.27 (0.70–1.84)] and weight esteem [1.38 (0.80–1.96)].
Given the negative consequences of excess weight, a large portion of the US population is seeking to obtain and maintain weight loss. Greater weight suppression (WS), or the difference between one’s highest weight and current weight, has been linked to nonsuicidal self-injurious behavior (NSSI). Thus, a key challenge faced by the US armed forces is producing soldiers fit to meet the physical demands of military service while minimizing risks linked to WS. This study examined the link between WS and lifetime non-suicidal self-injurious (NSSI) behavior and explored indirect effects in this link using survey data in two large samples. Sample 1 included 1011 college students (67% female, mean age=19 years). Sample 2 included 2461 participants from an epidemiological study (68% female, mean age=34 years). Models of direct and indirect effects were tested in MPlus using bootstrapping.
To reduce the link between WS and NSSI the study team used secondary analyses of existing data sets to identify factors maintaining this link. Through these analyses the study identified negative affect and body dissatisfaction as maintaining factors, and then identified two evidenced-based interventions designed to improve affect and body satisfaction. To address these concerns in both women and men, the study team modified the online-based intervention. They then compared it to a group-based intervention in a proof-of-concept study to evaluate acceptability and feasibility and determine our ability to weaken this link. The online intervention decreased negative affect and increased body satisfaction and it demonstrated greater acceptability and feasibility than the group intervention. Further testing was done on the efficacy of the online intervention in reducing the link between WS and NSSI by comparing it to a waitlist control group in a randomized control trial.
As hypothesized, greater WS was associated with increased likelihood of lifetime NSSI in both samples. Compared to controls, participants in the treatment condition reported greater decreases in likelihood of future NSSI [Cohen's d (95% CI) = −0.38 (−0.90–0.15)], weight/shape concerns [−1.19 (−1.75 to −0.62)], depressive symptoms [−1.00 (−1.56 to −0.45)], and significant improvements in appearance [1.27 (0.70–1.84)] and weight esteem [1.38 (0.80–1.96)]. These results suggest that the link between WS and lifetime NSSI may be accounted for by eating or mood-related pathology.