in regard to fasting being good for you, there are some benificial factors, i speak to a lot of professional body builders, and one of whome is muslim, and he told me that when he fasts during ramadan, his body is cleansed out, he finds that although he isn't able to build muscle during that period, it is very useful for cutting up, and that he is at a very ripped stage after, and it is only one month, mentally also, it does give u insight, i mean dawn till dusk, it makes u aware of what it's like to be hungry, and we get to eat at sunset, there are people in the world who dont get do eat for days, it helps to understnad what theyre going through to some extent
when people purely base things on faith, they do it blindly, but sometimes, there are justifications for certain things, and this is backed along with facts.
muslims do not drink alcohol becuase god forbids it right? lets say science had not yet progressed enough to show alcohol has bad effects on the body, would it mean that islam is wrong in saying alcohol is not good for u? now of course science has proven that alocohol (ehtanol) is actually a poison, and fair enough if u have a few glasses here and there its not terrible for u, but the general consensus is that alcohol isnt good, and there are many problems that arise due to its consumption, i think if u go to ur local doctor, or any american or european doctor they will agree