I lost 6 pounds on my last cleanse and gained it back almost immediately after I started eating again. But I maintain a healthy weight and lifestyle usually anyway, so I wasn't surprised. I can see how if someone uses this cleanse to drop the pounds and then goes back to an unhealthy lifestyle - you not only are gaining back the weight - you are in danger of obsessing over food and weight.
I was bothered when I gained the weight back - even though I was not over weight at all. I wanted my pants to be as loose as they were on the cleanse - but I got over it. But it could easily have become an obsession.
Healthy eating and excercise as a lifestyle is the key. It's a huge adjustment, but it's the only way to keep weight off.