"Obesity is not always going to be 100 percent reversible. I know no one wants to hear that, but I'm not in the business of selling snake oil. Some people can reverse it completely; others won't lose any fat at all; the majority can probably lose a substantial amount of fat but not all of it. Highly controlled diet studies in rodents show that obesity due to eating highly rewarding/palatable refined food is mostly reversible when they are placed back on low-palatability whole food, but they don't usually lose all of the excess fat, and the longer they've been obese, the less fat they lose (1, 2, 3). The capacity for the fat mass "setpoint" to re-establish at a lower level may diminish over time, varies between individuals, and probably also depends on other factors that no one currently understands. I think it's important to be kind to yourself, and not set unreasonable expectations."
I understand the point about setting reasonable expectations depending on one's health history, and that "not always going to be 100 percent reversible" means some may only change from obese to overweight. This is an intriguing statement and with so many success stories out there I would like to know if you (or anyone you know) are one of the very few who have not been able to lose any fat at all through diet alone?