Question Author
I've just checked, and the length of daylight during Ramadan (in London, 1st of July for example) is 16 1/2 hrs, that's a long time to go without food and water. It must have some (beneficial?) effect on the body. A Muslim friend who practices Ramadan looses a noticeable amount of weight after it, so it certainly isn't in his case a matter of compensating after dark, and anyone who has gone without food for a long period will know that you cannot eat the same amount of food that you would have done in a normal 16 1/2 hrs in one large go.
Also; many people eat fish on Fridays, but isn't the custom from not eating 'meat' rather, or probably not eating anything at all.
Squad; Do you not believe that there is such a thing as an "immune system"? It may be a makeshift phrase, but some people definitely have immunity to certain diseases.