You can't loose weight with the current food system unless you completely abandon it. It's literally impossible based on how the body works. Fad diets and weightloss programs don't work. You must address the problem at its root: How to deal with hunger. This is a hormonal problem.

Everything (hyperbole) you can buy in a supermarket is meant to make you feel full for an hour and then hungry again.

An alternative to surgery would be to just to continuously monitor blood glucose. The patient would immediately know when the food they are eating is messing up their body and the doctor can control the diet of the patient.