What Amount of Weight Loss Can Entail Anorexia Nervosa or Atypical Anorexia Nervosa After Bariatric Surgery?

Objective: Post-operative development of restrictive eating disorders can occur in patients after bariatric surgery. In children and adolescents with anorexia nervosa (AN) or atypical AN, premorbid body mass index (BMI) has recently been shown to predict total weight loss. We hypothesized that pre-operative BMI similarly predicts weight loss and the development of a restrictive eating disorder in adult bariatric patients.

Method: A PubMed search identified case studies/series of 29 adult females who developed AN or atypical AN/eating disorder not otherwise specified following bariatric surgery. Non-parametric Spearman's correlation (r ) between pre-operative BMI and total weight loss was calculated; a scatterplot was used to illustrate the relationship between pre-operative/premorbid BMI and weight loss in kg for 29 bariatric patients and 460 children and adolescents with AN or atypical AN as published previously.

Results: The correlation between pre-operative BMI and weight loss among bariatric patients was r  = 0.65 (p = 0.0001). Scatterplot data of this relationship fit the previously identified pattern in children and adolescents with AN or atypical AN.

Discussion: The prediction of weight loss by pre-operative/premorbid BMI appears applicable across the weight spectrum, from underweight to severe obesity, thus strengthening our hypothesis of underlying regulatory mechanisms for the development of AN and atypical AN. Such data may guide the determination of critical weight loss thresholds that trigger eating disorder development in predisposed individuals.