Patients' Preoperative Estimate of Target Weight and Actual Outcome after Bariatric Surgery

Evidence about the impact of psychological factors on weight loss after bariatric surgery is scarce. This study explores whether patients' preoperative estimate of target weight influences actual weight loss for different types of bariatric procedures. Patients eligible for bariatric surgery were instructed twice on how to calculate their expected target weight. They were divided into three groups based on their percentage excess weight loss (%EWL) and percentage total body weight loss (%TBWL). Weight loss 12 and 24 months after surgery was analyzed for each group and per type of surgery. Six hundred fifty-six patients participated in this study. Types of surgery performed were the Roux-en-Y gastric bypass (RYGB, 75%), sleeve gastrectomy (SG, 8.1%), REDO-RYGB (12.5%), and laparoscopic adjustable gastric banding (LAGB, 4.4%). Data of 622 and 410 patients were available for analysis at 12 and 24 months, respectively. Surprisingly, 415 patients (63.3%) overestimated their expected weight loss as opposed to our calculation, based on our own historic data. One hundred thirty-four patients (20.4%) estimated their weight loss correctly and 107 patients (16.3%) underestimated their weight loss. There was a significant higher %EWL 12 months after RYGB surgery for patients who overestimated their weight loss compared to those who estimated their weight loss correctly (p = 0.001). After 24 months and for other types of procedures, no statistically significant differences were found between the three groups. Despite instructions on how to calculate target weight, the majority of patients overestimated their weight loss. Actual %EWL 12 months after RYGB surgery might be influenced by setting a low target weight.