Yep. If you do an extended fast like this, be careful when you break it. Read a bit about how to avoid refeeding syndrome.

When I broke my first 5 day fast, I had a brief, but very strong, episode of dizziness, vomiting, and a strange, unpleasant out-of-body experience. I learned that this was probably due to sudden swings in levels of hormones and electrolytes that can occur when incorrectly breaking an extended fast.