when I first started 3 months ago, I couldn't eat 1200 cal a day either. my body has adjusted and I eat about 14-1600/day. a few days, I've even wandered up to 2000!

I feel full and even-keeled. I recommend the plan as atkins wrote it. I think it does matter where the carbs come from. different foods have a diff impact in insulin production which controls the whole game. if you want the details of how and why, atkins spells it all out. by cutting the carbs you don't get as hungry, as pointed out above. the fat keeps you feeling full.
it works for me.