I think 'mollusk' hit the nail on the head - you either cracked or bonked. Make sure you drink plenty of water or sports drink when you ride, even if you don't feel thirsty, and also take along some power bars, grapes, nuts, granola, whatever you like to munch on, and eat a little on your break.
I see a lot of people who try to diet and workout on a bike at the same time, thinking they will lose weight and get in shape faster that way...bad idea. Your body needs energy, you need to eat to supply that energy by eating...not pigging out, but rather by eating just enough to take the edge off anytime you feel hungry or low on energy.
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"Let us hope our weapons are never needed --but do not forget what the common people knew when they demanded the Bill of Rights: An armed citizenry is the first defense, the best defense, and the final defense against tyranny. If guns are outlawed, only the government will have guns. Only the police, the secret police, the military, the hired servants of our rulers. Only the government -- and a few outlaws. I intend to be among the outlaws" - Edward Abbey