I will say this, I am convinced that for a lot of addictions, all you can do is substitute one addiction for another. But if the new addiction is something healthy, then I think that is fine. But if you do become a diet addict, keep it scientific, don't follow every blogspam diet fad.
For social-media, I substituted a typing instructor game. So when ever I felt the urge to go doomscrolling or something, I would fire up a typing game instead. I keep a windows VM on hand just to play TypingMaster. It takes 3-5 minutes to complete one of the training sessions (which is probably less than you would have wasted on twitter). This helps kill the urge, and break the cycle. Plus it makes me a better typist. And when you can do 90wpm on QWERTY, switch to DVORAK.
If you have a common chemical addiction like smoking, coffee, pain killers, alchohol then the only safe approach is the taper/step down. Measure how much you take now and then commit to reducing that amount by about 10% per week. So you smoke 18 a day instead of 20 in your first week. That's not so hard, right? Whatever you do, NEVER try cold turkey quitting any chemical, at least not before seeing a doctor. Chemical withdrawals range from terrible headaches for coffee, to deadly DTs from alcohol.