I think that the argument that ' I believe X therefore Y is meaningless' is devoid of meaning. It's not meaningless to the people who believe in it.
And it's certainly not harmful. One is allowed to not fast if there is any valid medical reason why -- no one is required to go beyond their breaking point. A healthy person or even a person in moderate health can go some days without food and water. Ramadan only requires that the faithful observer go for the daylight hours without either.
I'm not a Muslim but I respect their beliefs, in fact today I ended up eating late because I had dinner with Muslim friends who are observing Ramadan and are leaving for their home country of Syria in a few weeks.