In general, we expect that gastric sleeve surgery patients will lose 50-70% of their excess weight over a 2-year period (though the majority of the weight is lost in the first year). Remember, however, that 50-70% excess weight is the average loss. Some people will do better and some a little worse.
As an example, a 5ft 6in person weighing 17st (240 lbs) has an ideal weight of about 11st (154 lbs); so an excess weight of 240-154 = 86lbs. 80% of 86lbs is around 60lbs. In other words, after sleeve gastrecomy, this person could expect to lose (on average) around 4 - 4½ st.
What happens to weight loss in the longer term?
One key issue is the lack of long-term results for the gastric sleeve and some experts believe that weight re-gain could be an issue after a few years. On the other hand, what evidence there is to date, looks rather more encouraging than some may have predicted. Only time will tell!