Is Losing 40 lbs in 4 weeks too fast?

I've been post-op for 4 weeks today and I've lost almost 40 lbs. I eat till I'm full and I work-out for almost an hour most days. I weighed 315 pre-op and now I'm down to 276. I'm taking all my vitamins, etc, but that seems way too fast. Is it? If so, what are the side effects? Thanks.

We greatly appreciate your interest in helping us build our Q&A database. To discourage vandals from posting garbage, however, we require people to register before posting.