Compulsive exercise to control shape or weight in eating disorders: prevalence, associated features, and treatment outcome.

OBJECTIVE: The study was aimed at assessing the prevalence of compulsive exercising to control shape and weight in eating disorders (EDs) and its relationship with treatment outcome.
METHOD: Compulsive exercising to control shape and weight, defined according to a modified version of the Intense Exercising to Control Shape or Weight section of the Eating Disorder Examination (EDE), was assessed in 165 consecutive ED inpatients entering a protocol based on the transdiagnostic cognitive behavior theory and treatment of EDs. Baseline assessment also included anthropometry, the global EDE interview, the Beck Depression Inventory, the State-Trait Anxiety Inventory (STAI), the Eating Disorders Inventory-Perfectionism Scale, and the Temperament and Character Inventory.
RESULTS: Of the patients, 45.5% were classified as compulsive exercisers, the prevalence being highest (80%) in restricting-type anorexia nervosa (AN), lowest in EDs not otherwise specified (31.9%), and intermediate in binge/purging AN (43.3%) and in purging-type bulimia nervosa (39.3%). Compulsive exercising to control shape and weight was independently predicted by the EDE restraint score (odds ratio, 1.32; 95% confidence interval, 1.06-1.64; P = .014) after adjustment for ED; the total amount of exercise was associated with EDE restraint, as well as with the Temperament and Character Inventory reward dependence. At follow-up, an improved EDE global score was predicted by lower baseline values, higher baseline STAI and STAI improvement, and lower amount of exercise in the last 4 weeks. Voluntary treatment discontinuation was not predicted by baseline exercise. DISCUSSION: Compulsive exercising to control shape and weight is a behavioral feature of restricting-type AN, associated with restraint and temperament dimensions, with influence on treatment outcome.