My doctor told me that if you only eat one meal a day, or if you cut your calories too drastically, the body goes into "starvation mode" and the metabolism slows down. This actually makes it harder to take weight off. She told me to eat several (up to 5) small meals per day, heavy on the protein.

I've also heard that having a healthy breakfast is important. Unfortunately, I'm not a morning person and the most I can manage for breakfast is a couple of pieces of toast. But I do make sure to load up on the protein at my mid-morning snack and at lunch.