Purpose: The main research aim was to inspect whether pre-operative body shape concerns and discomfort as Body Shape Questionnaire (BSQ) scores moderate post-operative weight loss trajectory in bariatric patients. Methods: Two studies were conducted. Study 1 analyzed cross-sectional data and verified the structural validity of the 34-item BSQ questionnaire on a sample of 327 candidates for bariatric surgery. Study 2 examined longitudinal data, with objective Body Mass Index (BMI) recorded every 6 months, from surgery intervention on, with 5 measurement occasions, from 111 patients who initially completed BSQ as bariatric surgery candidates and then underwent periodic medical post-operative follow-ups, over 2 years. Results: In Study 1, confirmatory factor analysis of a single-dimension model yielded acceptable fit indices and high internal consistency levels. Study 2 showed that post-operative excess BMI reduction trend was not linear and pre-operative BSQ scores moderated it, with a higher risk of weight regain in patients who initially were less concerned with their body shape. Conclusions: The present findings support the structural validity of the BSQ questionnaire in bariatric candidates and call attention on the role of pre-operative body shape concerns on post-operative weight loss trajectories over 2 years, in accordance with a pathoplasty model. They suggest the need for systematic attention on perceived body image and psychological paths aimed to help bariatric patients regain positive attitudes towards their own body. Level of evidence III, well-designed cohort.
