You need to eat more! I think the minimal levels needed by an active male is somewhere around 1800 calories (not 1200). Realistically with your activity you will need more than 1800...possbily 2500-3000 if you are looking for any kind of muscle gain. Remember the old saying that you don't grow muscle in the gym, you tear it down and grow outside with food, recovery and rest. If your calories are too low all you will do is lower your metabolism, destroy more muscle and strain your immune system. Eat, eat, eat.