In general, we expect gastric band patients to lose 50-60% of their excess weight over 2 years (though the majority is lost in the first year). Remember, however, that 50-60% excess weight is the average weight loss. Some people will do better and some a little worse.
A 5ft 6in person weighing 17st (240 lbs) has an ideal weight of about 154 lbs
Their excess weight is therefore 86lbs (actual weight of 240lbs - ideal weight of 154lbs)
Expected weight loss is around 50lbs (60% of 86lbs excess weight)
After gastric banding, this person could expect an average weight loss of 3.5 to 4 stone.
What happens to weight loss in the longer term?
The first laparoscopic implantation of the gastric band took place in 1993 so we have 20 years follow-up. The evidence we have is that the gastric band obesity surgery provides durable weight loss for the majority of people and that the gastric band material itself (silicone) does not appear to degrade in any significant way.
This is especially true of the latest generation of gastric bands which incorporate many design improvements. So whilst we do not yet have studies showing what happens to gastric bands after 30 or 40 years, we have no reason to doubt that the lap band will not function perfectly well for decades.
Read the Healthier Weight study of Gastric Band patients over 12 years