Be smart, obviously, with your diet, but as I have stated before the issue of muscle loss in my opinion is very overrated. I had to drop four pounds one time for a fight, I weighed at 152lbs. at 3.5-4.0%bf in the summer. Yup ripped as crap. I had to make a 147lb. fight so I went on a one month hypocaloric ketogenic diet with no refeeds. It sucked ass, I ate only about 2000 calories a day(far cry from my 4500 maintance load I was used to). I lost only two pounds during that month and stayed at around 3.5%-4.0%BF. Muscle sticks pretty well, the body handles the pressure and instead creates plateus! Plenty of diets to follow here, just pick one and follow it. The biggest thing is how committed and strict can you be? They all work, so work with them?