You are killing your muscle mass by doing this:

Let me make a few recommendations if i may, that would give you the same result while still allowing you to preserve most of your muscle mass. And possibly lose fat.

- Instead of eating less calories, eat less carbs. (It brings you the same level of focus as you would have if you had been starving yourself. Trust me.)

- Do NOT do any form of anaerobic excercise without having had atleast 250 grams of carbs within that day.

- Drink A LOT of water, pretty obvious but still.