It is possible to gain weight after a stomach stapling or a gastric bypass surgery
(which are not quite the same thing, although they are both forms of bariatric surgery). To understand how this could happen, remember that most people who need bariatric surgery for weight loss
have a lot of very bad eating habits going in to the surgery. Although the surgery does put a physical limit on how much food someone can eat, it does not automatically fix the food cravings and other habits that led to the weight gain in the first place.
In order to work properly and lead to a healthier weight, people with gastric bypass have to eat very small frequent meals. They also should not snack or eat between meals. This leads to weight loss.
However, the surgery can be 'cheated' if a person continually grazes or snacks on high calorie foods between meals. When this happens, weight loss will not occur and weight can even go up.
If you are considering a gastric bypass operation, you should make an appointment to visit a weight loss clinic and discuss your options with a bariatric surgeon
. They will explain the procedure to you and also what life will be like after the operation.