5%? Where does this come from?

The 60-80% EWL figure is what the 'average' patient achieves. Some people lose and keep off more, some lose less, but this is the AVERAGE. This number varies according to type of WLS, with the Band having the lowest long-term success rate and the DS having the highest. The Sleeve and the RNY fall in between the Band and the DS, and have similar long-term results.