Which diet to start?

[icelander68]

I am 40 years old and 165 lbs. I am 6'0" tall. When I gain weight it is always around my mid section. I was following another program and started at 180 and dropped down to 165. I recently found this program because I wanted to add muscle. When I checked my body fat today it is 17%. I tested out above average for cardio vascular test with a personal trainer. I have a little bit of definition in my upper abs but lower abs are not visible because I need to lose a little stubborn fat around my lower mid section. According to the plan I should do the fat loss diet. In order to get down to 10% body fat and mantain the current lean body mass I have I would need to drop down to roughly 152 lbs. Should I start the fat loss diet or modified mass? The book says Fat Loss but I am concerned with getting too thin. Then again is it a temporary thing to get a little thinner before adding muscle? Do I need to go as low as 10% body fat or is this a general rule of thumb. Can I just start modified mass when I am satisfied with my appearance? Just looking for some advice from those that have had to start fat loss first before starting the modified mass program.