Some people say that obesity can be irreversible! Is that true?
What has been noted is that permanent weight loss, where the person does not regain the weight loss is rare. Studies show only 5% succeed in keeping their weight loss permanent. Thus, it isn't impossible, but it is clearly very difficult, which is why maintaining a proper weight should not be treated as something that can be done later. Nor should you see that losing weight as reaching a goal and then forgetting about the diet. In other words, weight loss should be seen as a radical change in lifestyle (eating and exercise habits) that you are planning to continue for the rest of your life.
What is missing in the studies seems to be why weight is hard to keep off. The things I've read are filled with guesses, but no real answers. What really bothers me is that these "studies" seem to be pushing surgeries as a "cure." In other words, I suspect an monetary motive behind the "hopelessness" announcements.
What you can take away from this is that fad diets that have you eating things that you get tired of before the week is out and tell you that you don't need to stay on the diet won't work because people go right back to doing the things that caused them to get fat in the first place. It is also why I doubt surgery is going to be a cure either. People tend to be lazy, which undermines making a lifestyle change.