I've heard 1-2 lbs. a week and I've heard 1% of your body weight a week. Regardless of what actually happens on the scale, what is healthy is to eat healthy foods, exercise, and create a healthy calorie deficit. To ensure you get all the necessary nutrients, you should not go under 1200 calories without the supervision of a qualified doctor.
1st goal--216 (lowest weight since moving to NC): achieved 5/14/10
2nd goal--203 (lowest weight post college):
3rd goal--199 (Onederland!)
4th goal--189 (where I'd like to be before really trying to get pregnant)
5th goal--180 (100 lbs. from my highest weight ever)
6th goal--169 (overweight bmi)
7th goal--140 (normal bmi)
The Ultimate Goal...