Meth addicts are often very thin as well. /s
There's a large subset of people, the majority in my opinion, who are somewhat prone to addiction. Most are just a wee bit prone. They certainly won't peruse the streets for drugs. But, if something is readily available and socially accepted, they'll do it.
Before this was smoking, now its ultra-processed foods. Fast food, junk food, sweets type stuff.
It's probably still a boon, I'd say. I mean, I think being obese is probably healthier than smoking. But we didn't really "solve" anything, we just moved the problem.
Smokers used to claim that it suppressed their appetites. Not being a smoker, or obese, I wouldn't know. But it seems plausible as a (partial) cause.
But when people are dying slowly, and painfully, by their own hand and they can't stop, I personally consider that an addiction. In addition, we know ultra-processed foods are designed to invoke as much pleasure in the user as possible. In many ways, they suffer the same hyper-optimization that modern cigarettes do.
There's also some* evidence that part of the Tobacco industry shifted to food as Tobacco in the US died off. This is more circumstantial evidence. I think the "hard" evidence is that everyone smoked and was thin, now nobody smokes, and everyone is obese.
Regardless, I think we need harder and more proven solutions to the obesity epidemic. I think "willpower!" isn't working out for us, on a large scale. I'm rooting for Ozempic. And, fun fact, Ozempic also curbs nicotine and alcohol addiction.
It's heart and lung damage. Congestive heart failure, heart attacks, COPD, etc. A lot of these are slow, painful, and terminal.