Hungry for Change: Part 2... the empty feeling

Ok, we are less than 24 hours into this thing and I am feeling... miserable. I waited til 10am-ish for breakfast, which was ok (though, I am not a big oatmeal fan). Within an hour or two, lunch was on my mind and I was shocked at how hungry I had become so quickly. When the time came, eating the lunch portion of beans/rice/tomato sauce was DELIGHTFUL, until I realized that I had reached the bottom of the container and was still pretty hungry. Ugh. Two hours later, I am already very hungry and wishing so much I hadn't done this thing. My body is lethargic and my mind is having trouble focusing and working. My energy level feels like it's lowering, lowering, lowering and I could seriously fall asleep at my desk. I feel really really empty. How do people live like this? How do they work at physically demanding jobs like this? How? I am sad that this is how most people in the world feel most of the time, and I am sad that I am so miserable after less than 24 hours. I don't have any spiritual wisdom or insights, except that I feel empty and sad.