This is the phase that really works on cutting the fat.
The key here is that you don't want to cut all your fat before you build up your lean muscle mass so in the muscle building, you did both at the same time. You added muscle mass and trimmed your fat. Now that you have your lean muscle mass right where you want it, it is time to get rid of the rest of the excess fat.
Here, you are going to stick to the same schedule, the one of eating high-protein/high-fat/low-carbs during the week and carb loading on the weekend. The method to cutting fat in this phase is to simply cut the number of calories you are taking in daily. You can start by cutting 500-1,000 calories per day from your diet during the first week. After that, you can cut 500 calories per day with the goal of losing 1.5-2 pounds per week. If you are losing more than 1.5-2 pounds per week, then you need to lower the amount of calories to cut each day and if you are losing less than 1.5-2 pounds, then you can increase the number of calories you cut.
The key is to understand how your body reacts to the calorie cut and adjust accordingly. You might find that you lose quickly and keep your lean body mass at a lower calorie count than another person might. Find what works for your body. This is the phase in which you tweak and use trial and error to find the best foods and the best amounts for your body. Once you have reached your ideal level of body fat, you will then increase your daily calorie intake to a level at which you will be able to maintain your level of body fat and your lean muscle mass.