I'm in the middle of stage 2. Yes, I've seen differences that I like. Although, in trying to get the amount of protein the book suggests, I've ended up consuming more calories than usual and I've put on about 3 pounds, which is a bit discouraging since I want to loose 10 or so. I'm learning how to adjust and trying to rearrange the combination of food for protein content and calorie count so that I can turn the scale back in the direction I'm looking for, lol.
I think that if you're consistent with the workout plan, you'll definitely see improvement in time for your Jamaica trip. Good luck to you. (Wish I were going to Jamaica!

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