The title is pretty self explanatory, but let me give you an empirical story as to why not.
I had two cups of coffee today. Nothing to eat.
Much later. I'm tidying up my newly-cleaned room and packing for a trip. I have some music on and I'm singing along. My vibrato sounds more like a petrified adolescent male sound wave going through puberty. In other words, it was rather more shaky that it ought to be and usually is. Then I realized my hands were shaking. I was so confused. I had a lot of pent up energy. Then I realized and had two cups of coffee today and nothing to eat.
Second food observation of the day. Strawberries are deceitful. They taste so good that it doesn't really seem like they could be healthful, but somehow they are...