I know that a healthy goal is around a 1-2 lb loss a week, but I've lost almost 8lbs since Sunday. Honestly, I don't think I've made that many changes. I gave up soda and tea so all my calories are from food. I think I was eating about 3000 calories a day before, not sure, but I've but it down to about 1600 a day. Not on purpose, but by eating healthier things that's where I'm gravitating. I feel satisfied with this much but is that too low too soon? Sorry I'm on my phone so I hope this makes sense.
The first week is usually a big loss because of water weight. And the more you weigh the faster you lose in the beginning. So no I wouldn't be worried. It'll slow down eventually and average out to a few lbs a week.
I agree with beerab. Just enjoy this while it lasts....a lot of it is water weight. I don't think it's too few calories as long as you're feeling good.