It's a religious thing. It's a big set of rules people push to feel superior over other people without any evidence. Like any cult religious rules are superficial, so as to not limit access. Anyone must be able to achieve them easily, but not entirely without effort. There must be a big show about how important and massively advantageous they are [1], and especially how superior followers are to others. It can't actually make a difference, because otherwise the habit would spread which would negate the attention it calls to the cult/religion, so ideally religious/cult demands should be bad for you, but not too bad.
Besides if they weren't bad, why do even you yourself add medical warnings to it ? Things that are healthy do not come with big warning labels that you can fuck yourself up with it.
And then of course there is a discriminatory and dictatorial "state" structure associated with the cult that mostly treats people unfairly and forces them to work under very bad conditions. Well, sorry to say but islam certainly has that.
Nobody is superior because they slightly change their eating habits once a year. Nobody gets any advantage out of it. The best property I've ever known any of these things to have is that they get families together.