I'll do what i can.
Lowering the carbs prevents insulin from going into your system. Insulin acts as a regulator and will either lower the amount of fat you use as energy supply or increase it. The variable is the carbs you put in your body. Carbs have to be insulinized so if you don't give your self carbs you don't insulinize your blood stream and your body can keep using fat as fuel.
Eating a high percentage of fat is to aid you in keeping your body fueled. You need something right. People new to this have to cut the carbs and increase the fat and through time the body will change from a carb burning machine to a fat burning machine. For this to happen you have to adjust you insulin levels and to do that you want to cut the carbs. your body weight in grams of carbs is one step, then sub 100 grams is another step, for what around here is called extreme fat loss 50 grams of carbs a day or less is of high value.
Active lifestyle of enjoyable activities out doors, 2 resistance workouts a week and one day where you run your face off like a little kid springing for an interval of about 6 mins and you have your self some new guidelines. Privacy for this is often found after a song or two are listened to on an mp3 player while walking deeper into a local park.
PS i'm not primal and haven't read the book so i may be a little off. Regardless applying what I've shared works to achieve weight loss.