Not telling you what the do or anything, but if you care for a human life unfollowing or even reaching out (and getting blocked) is the best thing you can do. By following her and liking her posts you are reinforcing her beliefs she is on the right track. I said track because almost certainly she doesn’t feel she is skinny enough, if she had kept a steady below healthy weight that would have been one thing, but whe is on a clear path and her following will have a partial responsibility in case she might pass away from trying to please ger fans.