| Technically, you can take on a diet somewhere in the middle...where your physical activity will burn fat, slowly, while still allowing for muscle gains...also slowly. But if you lean hard one way or the other, you'll see faster muscle gains or faster fat loss.
On fat loss diets, you need to keep the protien intake high to prevent muscle loss. On muscle building diets, you tend to increase carb intake as this promotes anabolism and ensures you have a caloric surplus, triggering your body's response to build muscle due to the abundence of nutrients, and the increased physical workload of your workouts.
a pretty decent book/training routine is Body RX by A Scott Connelly. It has 3 6week intervals with different training and diets. you start by massing up then you tone up a little, then you cut the fat. There's a 4th 6week cycle for maintenance, or you can just repeat 1-3 over again until you get your body sculpted how you want. | 
