Uhh, I'd eat right to prevent gaining fat. I tihnk I read from Karky (I'm not sure, so dont' quote him or me on this) that healthy muscle gain is about 1lb per week. You can't gain no fat while bulking, but you don't ahve to just put on weight for the hell of it. You'll need to cut some later of course, but there isn't any reason to purposely allow yourself to become alot fatter in addition to putting on more muscule just because you know you'll cut.