I'm sure you've heard multiple reply's suggesting what someone thinks you should do, but the absolute best and only way is by trial and error. It is very important to know your somatotype to comprise the perfect diet for yourself. Try to figure out your body type %'s. This along with your age tell you a lot!
-Ectomorphic: characterized by long and thin muscles/limbs and low fat storage; usually referred to as slim. Ectomorphs are not predisposed to store fat or build muscle.
-Mesomorphic: characterized by medium bones, solid torso, low fat levels, wide shoulders with a narrow waist; usually referred to as muscular. Mesomorphs are predisposed to build muscle but not store fat.
-Endomorphic: characterized by increased fat storage, a wide waist and a large bone structure, usually referred to as fat. Endomorphs are predisposed to storing fat.
These categorizations are details for the people that are purely, just one body type; which is where the trial and error comes in. The majority of most people are a blending of these.
Example: I am almost pure endomorph(big boned). Growing up next to my brother, who is almost pure mesomorphic, I was fat, and told to quit eating so much, while my brother just ate whatever he wanted, and walked around looking like superman. It wasn't how much I ate as much as 'what I ate'. I am carbohydrate sensitive, meaning most sugars elicit an insulin release in my body which stops the use of fat as my energy source. If you don't burn it, you store it. The diet I go on while gaining bulk is 20/40/40 believe it or not, that's 20% carbs, which cannot be my constant diet because without carbs I don't get good fiber, and all the natural vitamins and minerals that are so important for my body. Knowing my body type help's ME know what to expect when 'off-cycle'. Under a proper diet, I really don't lose anything: fat or muscle, but that's because of my somanotype and underlying diet.
Someone losing a lot of muscle off-cycle could be leaning more on the ectomorphic side(Generally have trouble gaining mass to begin with). If this was me I would first increase my caloric intake as soon as I am done with my DMZ(or whatever). Even though I had increased my intake for the on-cycle, I would again increase my caloric intake as soon as I was done, or just increase my total caloric intake through out the whole program(On Cycle-3500, E-Control time-4000). To combat muscle loss, just try not to let your body get into a Catabolic state. At bed time, I take in 40g of Micellar Casein which has been shown to lump up in the stomach and slowly provide protein for up to eight hours, helping to keep the body in a constant anabolic state.
Like I said trial and error, and if done smartly it isn't that hard to find out where to stand.
