Zero calories or less per day after exercise - unhealthy?

Khavall

So I'm significantly overweight(5'11", 240 pounds. It all happened last year, too, going from 187, due to an incredibly stressful year and resultant scotch increase), and I'm right now trying to lose the weight as fast as I (safely) can. I've cut myself down to max of 1500 calories, pretty much just by slashing things I didn't need that I was eating(two patties for a burger instead of one, two chicken breasts instead of one. 4 Hot dogs with bun, no caloric drinks, etc.), and some days now I have to pig out at dinner to hit an intake of 1200 or above, and other than right before I eat, I'm not hungry during the day at all, nor am I feeling anything negative from a diet. My average intake is 1200-1400 calories per day. I also am working out twice a day for an hour, burning what's a quickly rising average of 700-750 calories each run. So basically, on my most eating and least exercising day, I'm taking in 1400 Calories and burning just through exercise 1400. On the other end of the spectrum are 1000 calorie intake with 1500 burned.

Obviously I should be eating less than I "burn" including Basal Metabolic Rate to lose weight, but am I going to far with the diet+workouts per day? Right now I'm feeling fine, sleeping well, and last week I lost 10 pounds. Also I'm drinking 4-5 liters of water per day.

So basically, is it a problem if before my resting calorie loss is taken into consideration my calories per day are zero or negative, or is this just going to keep resulting in quick weight loss?


EDIT: Crap, didn't see the fitness thread. Crossposted there, I guess this can be locked?