Has anyone here tried the Fast Metabolism Diet?

I've been following PB since 2011 and I haven't lost any weight at all, in fact, I've gained. So, I figured I would give this a try and be extremely strict with myself. The thing is, I pretty much feel awful so far. I'm on day 4. The first 2 days are pretty high in carbs and she tells you to eat grains. So, I ate gluten-free grains. The second phase is high protein and you only eat protein and vegetables. So that's all I've had the past day and a half. Both of the first two phases are low fat, which is something I haven't done, well, probably ever. I've also had to give up all dairy, caffeine, sugars, and artificial sweeteners. At least phase 3 allows healthy fats, thank god.

Right now I am having digestive upsets and I'm really tired. I didn't think I was hooked on caffiene but maybe I was because I am just so tired. I have lost 5.8 pounds and an inch off my waist since I started on Monday. That makes me want to keep going, but this tiredness and depressed state I'm feeling makes me want to stop and run into a bottle of wine.

If you've tried this, what was your experience? I'm thinking that if I can stick it out for 28 days and lose some weight (she claims you can lose as much as 20 pounds, but I'll believe that when I see it) then I can go back to PB and maintain since PB has generally been good for maintenance for me. If I lose weight and it all comes back I will be really mad though.