I'm really skeptical. I don't see how it could work.
When we are very overweight, we grow extra skin to cover our extra big bodies. We grow skin. Once you grow skin, there is no way to ungrow it. At least, that's what my surgeon told me, and it makes sense to me. How could skin just disappear? It's not a matter of our skin just stretching. Skin does stretch some, that's why we get stretch marks. But that's if we just gain a little weight. Gain 100 pounds or 200 pounds, and that skin did not just stretch. You had to grow more skin.
So if skin has just stretched a little, maybe you can do stuff to tighten it up. Maybe a body wrap would do that. But how could a body wrap ungrow skin? That doesn't make sense to me.