Poliquin would tell you to use at least 10 grams of Vit. C a day, although that probably won’t improve matters much. I think that 3X week is good for the GBC workout, but make sure you are getting proper post-workout nutrition. Not sure if your calories are too low but would be willing to bet that the timing of your food intake is off as well. Do not forget that this is a physically and neurologically demanding program and that you are not going to get off easy. You might want to incorporate the Ian King philosophy in that the first week on the GBC you should do weights that are below what you would normally do. The second week increase your weights to the point where they are equal with what you are used to doing. Finally in the third week shoot for personal bests by increasing the weight even further. In addition, how much stretching did you do before, during, or after the workout? Try taking a cold shower after your workout, using the coldest water that you can stand (but do not freeze yourself). Many strength coaches believe that this process can aid in reversing muscle breakdown and catabolism. If you do or are doing all of these things and still feel drained you are probably overtrained, not getting enough calories, or both.