I don't disagree with anything you wrote here. The "mind body connection" makes the line between physical and psychological issues hard to draw. I think the addiction framework is extremely apt.

But the point is that there is evidence that suggests certain factors cause you to eat more, but there is not really evidence to suggest that similar people do significantly different things with similar caloric loads and that it's just a matter of tweaking biology to make people process the same caloric load differently.

The problem with this study is that it's suggesting inflammation as a cause to obesity, but we know that the only long term cause for obesity is caloric surplus. Inflammation definitionally is not causing caloric surplus (in fact it's using more calories than one otherwise would) so it doesn't seem like a useful thing to be studying, and the fat gains from it don't immediately appear to be permanent. The most important thing to study is why people eat more than they should, not necessarily what happens in the body after they eat it (though, again, I agree with your larger point that those two could be connected).