I do not follow the ZONE by the blocks but I sure have been living a Zone life for about 4 years now. I started to get very tired and weak after every meal too. - and I was in my young 20's at the time. A bad diet wiill kill you! Keep up the good work and please know that you are on your way back to your old self. I know it is hard to beleive, but you will bounce back! Cheers, and please let us all know how you are doing.