Gastric bypass: analysis of weight loss and factors determining success.

Sixty-nine carefully selected patients underwent extensive behavioral modification training and a standard loop gastric bypass procedure. Patients were followed up at frequent intervals postoperatively to ensure their compliance with dietary requirements: (1) three small, solid meals a day, (2) slowly eaten meals with 5 minutes between bites, (3) no liquids with meals, and (4) cessation of eating immediately after hunger ceased. Analysis of weight loss data at a mean of 20 months postoperatively revealed that 90% of patients lost more than 50% of their excess weight, but that weight loss was inversely related to weight at operation (P less than 0.02) and to estimated pouch size (by upper gastrointestinal series) late postoperatively (P less than 0.01). Patients who failed to maintain regular follow-up visits postoperatively lost significantly less weight (P less than 0.01) than those who were seen regularly. Although fewer than half of the patients lost weight beyond the twelfth postoperative month, significant weight loss was seen in about one fourth of the patients as late as 2 years postoperatively when office follow-up was frequent and compliance with dietary measures complete. Abdominal pain and emesis occurred only when the patient failed to comply with the postoperative dietary regimen. Similarly, inadequate weight loss (premature plateau) was also associated with failure of patients to eat slowly and to stop eating when hunger ceased.