Thinking, of all things, can make us overeat. Studies show that intellectual activities -- from reading to writing -- can make people eat more than when they're merely resting. Researchers discovered that intellectual work leads to more pronounced fluctuations in glucose levels than rest periods, perhaps because of the stress of thinking. The body reacts to these fluctuations by demanding food to restore glucose, a sugar that serves as the brain's fuel. Glucose is converted by the body from carbohydrates and is delivered to the brain through the bloodstream. Because the brain cannot produce glucose, it needs a constant supply. Moreover, brain cells require twice as much energy as other cells in the body. Interestingly, studies in animals have shown that consuming fewer calories overall leads to sharper brains and longer life, and most researchers concur that the findings generally extend to human beings. Caloric overcompensation following intellectual work, coupled wi...