1- Nutritional Ketosis (Bullet Proof Reference)
(The Ketogenic diet for health)
2- Diet Medications (4 new diet medications)
3- Bariatric Surgery
Only banding surgery is solely a restrictive mechanistic procedure and is being done much less often.
If you look on internet this is how it answers the question. It is an old viewpoint.
I learned a different answer when I took the American Board of Obesity Medicine Exam 12-15
Gastric bypass causes increase in GLP-1 which decreases hunger by ileal brake.
Gastric Sleeve causes decrease in Ghrelin
Latest Science on Obesity summed up at this link