For the start (especially since you are looking at losing 100 lbs) this is normal. Your water and glycogen loss has accounted for a lot of that (which is why so much was lost so fast). If that wasn't the case, I would say that you are losing it far too fast for my liking
. You should start seeing a dramatic slowdown in a few weeks and will most likely see about 2 lbs lost a week. Keep it up Strange Famous, you are doing great!