Eating disorder: lost 6 pounds in two days!?!?!?!?!?!?

I don't eat much, intentionally, usually under 400 calories a day. But lately, I've been around family more and pretty much forced to eat unless eveyone finds out I hate food. The only reason I really eat is to keep myself awake, I tend to not sleep. Today especially, I ate fast food, added it all up and found 940 calories. Yesterday I binged on chocolate (8 Hershey's miniature chocolate eggs :( ). Other than that I'd been having less than 200 calories since Sunday. Anyway, two nights ago, I weighed myself. 209 pounds (I've been overweight most of my life). Tonight, 203 pounds. How the heck did that happen? I was expecting to be at least 212. Should I be worried that I've been eating more, and losing more? I haven't been excercising much at all, unless you count nightly fourwheeler rides. After Sunday, I'll be right back to my less-than-400-calories-diet and exercising daily. I just want to know if I should be worried that I lost 6 pounds in two days... Thanks. And if you're going to answer in negativity to my eating disorder, don't even answer.