Efficacy of Interventions Aimed at Reducing Explicit and Implicit Weight Bias in Healthcare Students: A Systematic Review and Meta-analysis

We conducted a systematic review and meta-analysis to determine the efficacy of interventions aimed at reducing weight bias in healthcare students, and to explore factors that may impact intervention success. A systematic review and random-effects meta-analyses were conducted by including studies that examined the efficacy of weight bias reduction interventions for healthcare students. Of the 3463 journal articles and dissertations screened, 67 studies (within 64 records) met inclusion criteria, with 35 studies included in the meta-analyses (explicit = 35, implicit [and explicit] = 10) and 32 studies included in the narrative synthesis (explicit = 34, implicit [and explicit] = 3). Weight bias interventions had a small but positive impact, g = -0.31 (95% CI = -0.43 to -0.19, p < 0.001), in reducing students' explicit weight bias but there was no intervention effect on implicit weight bias, g = -0.12 (95% CI = -0.26 to 0.02, p = 0.105). There was considerable heterogeneity in the pooled effect for explicit bias (I = 74.28, Q = 132.21, df = 34, p < 0.001). All subgroup comparisons were not significant (p > 0.05) and were unable to explain the observed heterogeneity. Narrative synthesis supported meta-analytic findings. The small but significant reduction of explicit weight bias encourages the continued testing of interventions, irrespective of variation in individual intervention components. Contrarily, reductions in implicit weight bias may only be possible from a large societal shift in negative beliefs and attitudes held towards people living in larger bodies.