I've watched waay too many videos with pros now to not notice that pretty much every single one of them switch from meat to fish the closer they get to a contest. Most recently I watched a video with Phil Heath on flex where he said he gets "thinner skin" by eating fish.
Is there some scientific explanation for this switching of protein sources? The only thing I can come up with is that the fish they eat has less fat in it than beef... but would eating really lean meat vs. fish make any difference? If so, why?