One of the women I work with weighed almost 400lbs and went to doctors asking about both procedures. The company's health insurance at the time wouldn't pay for all of it and she didn't want huge medical bills.
So she decided to just change her eating to match the gastric bypass eating. Small amounts of the foods and liquids on the post surgery eating plan, several times a day, etc. She ended up losing weight on her own. She made herself not cheat or eat more that they'd let a real gastric bypass patient.