> And to be clear, you can't not lose weight with a calorie deficit

That's true, but in a useless way.

You can't die of cancer if you get rid of all the cancer cells in your body -- that doesn't help us treat cancer.

The problem isn't whether caloric deficit works. The problem is why some people are unable to maintain caloric deficit.

This appears to be complex, and includes stuff like gut flora, medication, strong cognitive biases, among others.

I guess I meant it as an umbrella term for all the things that I think matters for weight loss. Insulin resistance and the propensity to store more fat than to keep it as glycogen in the blood ready for burning.