These are two completely different operations. The gastric bypass procedure is a restrictive and malabsorptive operation. With the proper nutritional counseling and behavior modification, you can get close to your ideal body weight. This operation can be performed and has excellent results in patients with a BMI >45 and those who have a metabolic condition such as diabetes. This operation can place diabetes in remission in almost 85 - 90 percent of cases and/or significantly decrease the need for medication.
The lap band can be an effective operation for the well motivated patient who will excercise routinely and follow good nutritional advice. The band is purely a restrictive procedure and does not change your absorptive capacity, therefore it is much less effective overall. The lap-band is best for patients in the BMI range of 35 to 45. Although patients with higher BMI numbers may be candidates for the band, these patients typically do not lose significant amount of weight (there are always exceptions).
The lap band has a lower risk profile than the bypass but it still has complications. It makes sense then that a procedure with a lower risk profile has typically less weight loss results as compared to one with a higher potential complication rate such as the gastric bypass.
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