The things is there are different ones.
The groupon ones tend to be gastric mind band.
Hypnoband brand is different. You cannot do it at all in 2 sessions.
You have an intro session, an NLP session, the operation and then adjustments. You have the smells and sounds of a theatre. You also have a cd to listen to in between each appt. It has worked very well for some.
But it defo is mind over matter.
I did the MP3 ones and lost weight. But had to listen to it everyday to keep it working. That worked out too much in the end, as it is not always easy to get that time.
I bought a couple off Amazon. Cheaper to try then the sessions. I think they may even e good for people who have really had an op but not changed their mindset.