That's the thing about all these complaints of "unrealistic" superheroes.  Of course they're in   7ffa  incredible shape, they're superheroes.  Doing the kind of stuff that Batman does requires an amount of strength and agility that fatties simply do not have.  They are unrealistic in the sense that they are near physical perfection, but you MUST be near physical perfection to do the kind of stuff that they do.  So in that sense, they are very realistic.