The cure is to teach from an early age about impulse control, moderation, and how to spot signs of addiction in yourself early. This goes for:

Social media

Drugs and alcohol

Food

Or literally any other addiction. I don't think this is a useless thing to discuss.

Well, of course if you’ve been jacking heroin for 30 years and all your veins are destroyed beyond repair it’s useless. It’ll take as much, or even more, to return back to normal.

Heroin changes brain chemically, it's (more) serious addiction than obesity, again being a little insensitive to obese people, but they're bad in comparison. And there are degrees of truthfulness & wrongness right!

About the point you're making, two generations before you and me, people where fit, more attentive & generally healthy (outside vaccines that prevent diseases now & positive effects due to advancements in medicine), what changed?

Not as platitude, but go from first principles, the choices you make everyday effects your mind (& the time you spend on particular activities), and if they aren't life affirming (for lack of better words), in due time you limit your options (ie less choices from your mind, bad food or less bad food or multiple bad ways to spend your time?), till you proclaim from high top mountains 'oh god, I'm helpless without acceptance from some higher power!'

This isn't to say, I'll be as preachy and asshole(ish) to a friend or someone I care about in similar need, I'll probably say 'seek medical help etc' like you. But thinking things through & arriving at truth is important, don't you think?

This is different to mental strength or controlling yourself etc, it's more about self reflection & freedom through discipline, respecting your life, decisions & thoughts more than your impulsive emotions in an ever distracting world, that kind of thing..

I don't think I'll change your mind or this will come across in good faith, that's okay, I'm in a reflective mood, and it's awfully chilly outside :-)