The Nissen/Fundoplication is not considered a treatment for obesity. While some of the stomach is used to wrap the esophagus it does not cause a significant difference in stomach size. I did find a research article that investigated weight loss after LNF surgery. On average a year after the LNF procedure people lost 8.9 lbs. People who weighed more before the procedure tended to lose more than those who didn't.
So, while it is possible to lose weight after the LNF procedure, one shouldn't expect "massive" amounts based on the surgery alone.
As a life and death situation, I had the LNF surgery with Vagotomy and Pyloroplasty in September 2009 weighing 97 lbs going into it. That week I was in the hospital I had lost 7 pounds. My doctor assumed it was Superior Mesenteric Artery Syndrome, which it turned out negative. To this day I have not been able to keep 100 pounds on. To give you an example, I weighed 117 pounds before I got sick in February of 2009. A total of 27 pounds lost...My lowest weight dropped to 89 pounds.
To make a long story short, I had to go on TPN for almost 3 months to gain weight. I gained 15 lbs on this treatment only to lose it within a few months.
Frustrated and upset, I went to my doctor in December 2010 and asked him to put me back on the TPN for a month to get me up over 100 pounds.
Guess what? I gained 10 pounds and have lost 5 of them already.
I am at my wits end with this as is my doctor. I am a small build person, so any weight I lose is noticeable. I am tired of people thinking I am anorexic. The worst part of this is I lost my job over it and living in a small town, everyone knows my health condition and are hesitant to give me a job.
I am hoping to find some answers soon.