But this intelectual knowledge doesn't really help if your body is telling you it's hungry all the time and it's hard not to eat something. Better choices can help, because different calories deliver different satiety; but some people don't get much satiety no matter what they eat.
Calories in vs calories out is true, but it's very hard to measure calories out, so it's sometimes helpful and sometimes completely unhelpful.
These drugs seem to help a lot of people in different ways, but if the underlying issue is that they don't get the satiety signals they need to eat healthy amounts without it, of course it's not surprising that when they stop medicating, they stop getting the satiety signals.
There's a lot of variance among humans, but everybody seems to want a one size fits all approach to eating. That doesn't work; you have to find all the things that work for some people, and then try the most promising options until you find something that works for you. Many people crave novelty, and anyway people change over time, so something that works for someone today might not work for them next year, etc.