Eating disorders and disordered eating are elevated in bariatric surgery patients both before and after surgery. Yet there is currently no consistent definition of disordered eating following bariatric surgery that takes into account the altered gastrointestinal system in patients. Consequently, reports of the prevalence of disordered eating following weight loss surgery are highly variable and dependent on the definition and assessment measure used. This systematic review was performed to evaluate the definitions and measurement methods currently used to identify and assess disordered eating in adult bariatric surgery patients. One hundred articles evaluating post-surgical patients up to March 2012 were identified. Articles featured 35 questionnaire and 23 interview assessment tools. Variations to diagnostic criteria included changes to the frequency, duration and amount of food requirements for binge eating, and inconsistent use of other disordered eating definitions (e.g., grazing). Only seven (20%) of the questionnaires and one (4%) of the interviews had any reported psychometric evaluation in post-obesity surgery populations. The Three Factor Eating Questionnaire and Eating Disorder Examination were the most frequently used questionnaire and interview respectively. Various amendments have been made to measures to account for the post-surgical eating context, however none of these amendments have been psychometrically evaluated. The heterogeneity of definitions, diagnostic criteria and measures and inconsistent reporting of results limit interpretations and conclusions. Results highlight the need for a consistent definition of disordered eating and for current assessment measures to be (a) psychometrically evaluated in bariatric surgery patients, and (b) adapted to account for the altered gastrointestinal system in patients following surgery. Valid and consistent diagnosis will enable accurate assessment of the prevalence of disordered eating after surgery and the impact of disordered eating on surgical outcomes. This will also facilitate appropriate targeting and evaluation of disordered eating treatments following surgery.