Grazing in adults with obesity and eating disorders: a systematic review of associated clinical features and meta-analysis of prevalence

Grazing, the unstructured, repetitive eating of small amounts of food, is a pattern of eating which has been associated with negative outcomes following bariatric surgery. Less is known about grazing in eating disorders and in non-surgical obese samples. This review aims to critically examine the existing research on the prevalence of grazing, associated treatment outcomes, and clinical correlates in adults with eating disorders and/or obesity, in clinical and community settings. A systematic electronic database search yielded 38 studies which met inclusion criteria for the review. A meta-analysis was conducted using prevalence data from 32 studies (31 datasets). Mean pooled prevalence in obesity (n = 26 studies) was 33.20% (95% CI [27.54, 39.11]) at pre-weight loss treatment, 28.16% (95% CI [17.86, 39.73]) at follow-up, and 23.32% (95% CI [3.07, 52.04]) in the community. Nine studies provided prevalence estimates in eating disorders: 58.25% (95% CI [52.75, 63.66]) in bulimia nervosa; 67.77% (95% CI [44.96, 87.13]) in binge eating disorder; and 34.31% (95% CI [26.56, 42.49]) in anorexia nervosa. The results suggest that grazing is widely prevalent within obesity and eating disorders. There is mixed evidence to suggest that grazing (especially a “compulsive” subtype including a sense of loss of control) is associated with poorer weight loss treatment outcomes in obesity, lower mood, increased eating disorder symptomatology, and decreased mental health-related quality of life. Differences in the operationalisation of grazing may account for inconsistent findings in regards to specific correlates and risks associated with this behaviour; therefore, there is an urgent need to refine and adopt a consistent definition of grazing.