I am in 12-week program, my 6th week. I guess I am doing fine, the effects are already visible but it seems that I don't eat enough. I mean, first four weeks I was doing great, but now I feel as if I do not have enough strength and stamina for workout. I also started protein diet, perhaps that was a mistake. Now I am starting to get nervous, I do not want those past weeks to go to waste, but the diet has also shown effects. What am I to do?
I think that you did a mistake by commencing diet (no other then protein one) with a serious training program. Balanced diet is the best for combining with any kind of exercise. I know that from my personal experience. Protein diet really has effects but removing completely one basic nutrient from meals is simply not a good thing. Especially if you know that carbon hydrates are the basic and only food our brain needs. That is why you are becoming nervous. I would rather stop with diet and continue eating normally then stop with the program.