ur body needs protein, carbs, fats, vitamins to build muscle. if u go on low-carb u deprive ur body of some bodybuilding nutrients, and same with fat. but i notice when i go on low-carb diets i dont tend to build muscle as easy, but when i go on low-fat diets i build muscle better. For instance, i went on low-carb 2 weeks ago and ran 2 miles every morning, i only lost a pound and i felt like i was getting bigger on the sides...then i gave up after realizing i only lost a pound, so i started eating carbs again and i felt slimmer and looked slimmer, i loooove IHOP...i went to IHOP like 4 days in a row and had like 3-4 different platters, all carbs of course- little fat. I started eating low-fat i realized, and i felt like i was losing weight and still gaining some muscle. If u HAD TO diet while trying to build muscle, would u choose low-carb or low-fat?? OR, would u forget it and just eat whatever. I think im planning on bulking for 4-5 months when i get to college, then cutting to lose fat.