Good point. If it works it's great. But i am really sceptical.
Does it come with support? The balloon helps you to eat less, cause you are full earlier. What happens when the balloon dissolves? People eat more again and will struggle to keep the list weight down, cause they will be hungry again. If you start being more active while the balloon is in place and keep going then it might work, but just relying on the balloon to keep the weight of, I am not sure.