Specifically, that weight loss in the long term is not only practically impossible but also actively harmful.
But what if I want to be more muscular? Is that impossible as well? Not sure.
That said, many interventions for the obese would help all of those other things, even if hypothetically you could vary them independently. And those comorbidities are often the things making those anti-obesity interventions so ineffective.
Muscle wise, lifting weights and eating a surplus is usually good enough to see significant gains for an untrained individual. There are "hard gainers," but their issue is having difficulty eating enough; that's not an issue for people who are overweight.
> But what if I want to be more muscular? Is that impossible as well? Not sure.
That is impossible. There is no way to build muscle — gyms are scams. Read “The Muscle Myth” and “The Protein Delusion” by Ivana Tinkle.
I’m curious what the core argument is from these books. Could you tell me more?
What research shows, unfortunately, is that taking a bunch of people in some kind of shape they don't like, applying a point-in-time intervention that changes it, and then going back five years later usually results in finding they went back to how they were before.
That doesn't mean changing your physical condition for the long-run is impossible. It means there is no such thing as a point-in-time intervention with permanent effects. You need to make a permanent lifestyle change to see a permanent effect. The overwhelming majority of people will never do that, but it absolutely does not mean you can't do it.
Depends what you mean by “long-term” but now at 30 I am both lighter and more muscular than I was at 18. Based on the results of a recent physical exam I don’t see any harm having been done.