Blame it on the brain. Researchers at Yale have found that our brains respond differently to sweet tastes and to calories. The brain is hardwired to seek out sugar to provide itself calories, but it considers sweetness separately, and it will go for the calories - energy - every time. "It turns out the brain actually has two segregated sets of neurons to process sweetness and energy signals," the Yale study’s senior author explained in a press release. "If the brain is given the choice between pleasant taste and no energy, or unpleasant taste and energy, the brain picks energy." The study found that both sweet taste and nutrient value register in an ancient brain region called the striatum, which is involved in processing rewards. In studies with mice and sugar, the researchers found that signals for taste and nutrients are processed in two separate areas of the striatum. One, the ventral striatum processes taste signals while the other, the dorsal striatum responds to energy signals. As far as eating behavior is concerned, the study showed that the brain chose signals that sugar (even sugar made to taste very bad) was delivering calories every time. The bottom line: Our human sweet tooth evolved to ensure that we eat enough to provide our brains with the calories it needs to operate at peak efficiency, but it is our brains desire for calories - not sweetness - that dominates our strong cravings for sugar, the researchers reported.