how does your diet look like right now? and your workout schedule?

from my own experience i found i lost a considerable amount of muscle (meaning my bench went down, and it sorta felt like i shrunk a bit) by lowering the frequency or intensity of my resistance training, and upping my aerobic/HIIT workouts... instead of doing 5days resistance, 2days cardio... i did 5days cardio and 2days resistance... did this for a month and lost a lot of fat but my bench went down from 180lbs to 160lbs (i felt like crying when this happened)

cardio's known for burning fat really quickly, and burns muscle pretty fast too... so there's no need to starve yourself on a low fat/protein diet, if you change your diet, you're in the danger of gaining fat

summary: do more cardio (very catabolic after 30mins), less resistance, same diet (i hate the "hungry" feeling... who doesn't haha)