I started the zone 3 weeks ago and I felt great the first week and lost 6 pounds. And now i'm tired and sort of weak feeling. I've tried to look at what I'm eating and see the problem but the only thing I can see that I'm doing different is that on the second and third weeks I didn't eat as much fruit but I replaced it with veggies.

Is that what's wrong?

colleen, to be able to offer suggestions, we'd need to know more about exactly what you're eating, how much of each food, and when you're eating it, as well as your LBM, body fat % and activity level.