I've been thin my whole life, no matter what I do. I crave mostly sweet foods or foods that usually give some one energy but I never feel energized. I'm actually so tired all the time that basically all I can do is eat, watch tv and sleep. Yet I'm still skinny. As I get older (I'm 23), I get more tired and have bowel movements sooner right after I just eat. It used to take a few hours for me to feel like I have to go to the bathroom but now it can be an hour or less. Is that normal? Can my metabolism be way too fast?