Gastric bypass surgery can result in long-term weight loss. The amount of the weight you lose will depends on the type of the weight-loss surgery & the changes you make in the lifestyle habits. It was possible to lose half, or even more, of the excess weight within 2 years. As long as you stick to certain low fat diet & exercise recommendations, all kinds of weight loss surgery may achieve good & often impressive results.
The gastric bypass diet may also help to recover from the surgery & transition to a way of eating which is healthy & supports the weight-loss goals. Remember that if return to any unhealthy food habits after the weight-loss surgery, you may not lose the excess weight, or you may even regain the weight which you have lose.
A person who has undergone gastric bypass can expect to lose 70% of their excess body weight within 2 years. The weight loss will tends to be more rapid in the 1st year (60% of the excess weight lost) then it will slows in the 2nd year, with only additional of 10% of weight loss.