['Success with preoperative weight loss (PWL) is often mandated by the bariatric team to assess patient compliance and has been suggested to correlate with improved postoperative weight loss outcomes.', 'We performed a retrospective analysis of 1629 consecutive patients undergoing laparoscopic Roux-en-Y gastric bypass at Duke University Medical Center. Patients with a preoperative weight gain (PWG) or loss of > or =10 lb were compared. Patients with <12 months of follow-up were excluded.', "We found no difference between the 2 groups (PWG, n = 115, PWL, n = 88) with regard to age, gender, race, preoperative body mass index, presence of co-morbidities, or interval between the initial program-entry weight and surgery (149 versus 141 d). No difference was found in the percentage of excess weight loss (EWL) at 12 months, when calculated using the patient's immediate preoperative weight (PWG group, 63.5% EWL versus PWL group, 63.9% EWL, P = NS). If the %EWL was calculated using the initial program-entry weight, the PWL did confer a transient postoperative weight loss advantage; however, this did not persist past 24 months postoperatively. At both 12 and 24 months, the resolution rates of diabetes (82% versus 83% at 2 yr; P = NS), hypertension (48% versus 42% at 2 yr, P = NS), and continuous positive airway pressure discontinuation (87% versus 87% at 1 yr, P = NS) were equivalent. No differences in perioperative complications or conversion rates were detected. The operative time was slightly longer for the PWG group (119.7 versus 104.9 min, P = .02)."] Does preoperative weight gain predict failure of weight loss or co-morbidity resolution of laparoscopic Roux-en-Y gastric bypass for morbid obesity?