Does percent body fat affect BMR
 

And if it does, how so? I have heard that if you have more lean muscles, you burn more calories. The larger you are, the more calories are needed to maintain size. So does fat or muscle require the most calories for maintainence if your weight is unchanged and would that affect caloric needs?

If you have two people at the same weight, same frame size but one has a lower body fat percentage (i.e. large muscle mass) then that person will have a slightly higher BMR. However, it's not really a significant amount, I vaguely remember hearing something like an increase of 10lbs of muscle (something seriously hard to do!) is equivalent to 100 calories more a day. I don't remember the exact numbers, though.