I feel that I must go beyond what EmperorNero first said when he said "you're screwing yourself over" - its too late; you've already done it. One week without calories does such a number on your metabolic needs you would not even want to know how severe. If your body required 3000 calories to maintain weight before it may be easily under 2000 now. See my point? Whereas before you could cut down on calories to 2000 and lose two pounds of fat a week (a pound of fat has 3500 calories), now you need to drop to 1000.
Course, thats best case scenario; really your body is holding onto fat now. It doesn't need muscle - especially if you are not doing weigh bearing excercise - muscle will go first, fat last.
Starvation diets are very in appropriate to lose bodyfat. If you want to lose it you have to do one or all of the following four things:
1) increase calorie output (ie, excercise)
2) speed metabolism (excercise does this, especially weight training - muscle really burns calories)
3) decrease calorie intake intelligently
4) Change calorie composition
I know that right now you've lost 10 pounds and you think thats great. I don't want to rain on the parade too much but when people say you're going to regain this weight they are right - if you don't its only because of a constant battle and war not to. If you want to lose weight do it the hardway: This means longterm changing of eating habits and excercise habits. I've been through this myself, and I've watched a friend damn near fast off 60 pounds of fat; the muscle he lost was insane. He is now back up to his original weight, less healthy than before.
For the record you didn't lose 10 pounds of fat. 10 pounds of fat is 35000 calories - even if your body required as much as 4500 calories a day (7 days or so) at the start, after even 24 hours it would have decreased it's needs. I weigh about 185 pounds. If I stopped consuming any calories right now I guarantee that in 2 days I'd weight 4-5 pounds less. Its water and other non-fat substances for the most part. Sure there is some fat, there is also muscle.
BiB