Well even though this might be wrong I will try to explain it (even though I'm pretty uneducated in the topic) I would think that your body would focus on eating away your muscle and then move on to the fat because your body knows it only needs a certaint amount of muscle, and the muscle that you've gained from workingout isn't nessisarily "needed" in order to survive, on the other hand your body needs the fat to maintain a stable body temperature.

Will you lose strength? I would definatly say so, working out while fasted your not going to be able to do NEARLY as much weight, and then when you go to workout when your not fasting I'm sure that your body won't be as strong from the muscle lost. Even though there is a difference between having lots of muscle and being strong, (because size doesnt always equal strength) I'm sure you will lose alot of both.

Hope some of this is right (maybe someone else can chime in to clear up some of my misunderstandings)