You can give advise and try and help people but they have to really WANT that advise.
If they don't really want your advise then don't offer it, That's what I've learnt. and if someone says that you're wrong just ignore them, so long as you're happy then it doesn't really matter what other people think, and if what other people think makes you unhappy only then should you think/worry about it.
I didn't want to go into long, long detail but I generally say "This is what I know works" and I'm very skeptical on what I take in, it has to be researched, scrutinized and tested by people in the field, Doctors, researchers, sports scientists/trainers and so on, not what someone put on the internet.
I don't throw out advise to people, well I'm not sure what to call it, I just post something online and if people like it then good. However, these days people are so adamant to prove people wrong and will jump on any bandwagon that I just now think "Yea whatever. I'll carry on with what I'm doing, you do what you're doing, we'll see who's better off"