Factors Predicting Weight Loss in Females After Gastric Bypass Surgery

Obesity has become an epidemic in the United States, especially in the past 30 years, with the rate of obesity more than doubling. Bariatric surgery has become a more common method to deal with obesity and its associated sequelae. Before being approved for surgery, one must engage in a psychological evaluation to determine whether one has the psychological and emotional resources necessary to proceed with gastric bypass surgery. The objective of the current study was to determine whether specific psychological variables obtained during the psychological evaluation for gastric bypass surgery, specifically, the validity and clinical scales of the MMPI-2 and the SCL-90-R, and psychological variables obtained during the clinical interview, could be used to predict success post-surgery in terms of percent excess weight lost (%EWL). It was expected that clinical elevations on these scales would predict lower weight loss. Results indicated that the only significant predictor of outcome, in terms of a higher %EWL, was a lower score on subscale Pd2 (Psychopathic Deviate: Authority Problems) of the MMPI-2 at six months post-surgery. However, higher scores on scale 2 (Depression) and F (Infrequency), as well as a greater number of Axis I diagnoses, approached significance as predictors of %EWL at 6 months post-surgery. In addition, a greater number of self-reported coping mechanisms and a higher score on scale 1 (Hypochondriasis) of the MMPI-2 also demonstrated a trend towards significance for being considered significant predictors at 1 and 2 years post-surgery, respectively. None of the hypothesized predictor variables were found to be significant predictors of %EWL at 3 months, 1 year, or 2 years post-surgery, or for maintenance of weight loss from 1 to 2 years post-surgery. Limitations, strategies to overcome these limitations, and directions for future research are discussed.