I have seen some really obese folks, the kind who are three times my sizes. I think if I am in that position and someone offered me one of this weight loss surgery free of charge, I will probably take it.
Otherwise, I wouldn't dare to undergo the surgery because it is an invasive one. However, there are sites like the link I provided who provides counseling to their patients, find them the best option and takes care of the after surgery recovery.
It is a major surgery and needs one discipline to eat with care before they can undergo it. Otherwise, they will end up in square one again.