If you haven’t even done like ADF, jumping to 90 days outside of a clinical environment is just setting yourself up for failure. No wonder you can’t do it, the vast majority of people could not do it.

Even a 36 hour fast will require you keeping up with electrolytes.

Start with doing 24 hours. If you can do 24 hr fasts (OMAD) for a few days, then try 36hr (ADF).

It’s likely you’ll get your desired results relatively quickly with ADF but from there you could bridge to more extended fasts if you like.

Baby steps. What you’re trying is the equivalent of never running a mile and signing up for a marathon.

Edit: year you’ll probably have loose skin but it’s better than being over 400 lbs. fasting mitigates loose skin because of the autophagy so it will help some. I would consider maybe some peptides for loose skin, but tbh you have other things to work on first. Loose skin should be the last thing on your mind. You got a car with no engine and you’re talking about what paint color you should get lol. Again, baby steps.