You seem to not WANT to give up protein shakes... how "heavy" are your shakes? if it's just water I don't see a problem but if they're loaded with fruits or whatever and you have many of them a day I could see you dragging ass a little bit waiting for your body to process it all. Also, if P90x is too strenuous then naturally your body will want to rest even during the day. I've found better energy levels lifting 2-3x a week and sprinting 2-3x a week. I'm going to diversify in the future but for now that's all I'm doing and I'm losing weight and feeling good. Even if you're trying to gain weight, maybe you're burning too many calories on P90x and not getting enough through food?
I used to seriously post here, now I prefer to troll.