Fructose, it appears, is the gift that keeps on giving. Unfortunately, it keeps on giving your body food that it doesn’t need, by turning off the mechanism that tells your brain that you’ve had enough, thanks. The Boston Globe reports on a small study conducted at Yale University that used magnetic resonance imaging to track blood flow in the brain in 20 young, normal-weight people before and after they had drinks containing glucose or fructose in two sessions several weeks apart. According to the Globe, the scans showed that drinking glucose ‘‘turns off or suppresses the activity of areas of the brain that are critical for reward and desire for food,’’ as one study leader put it. With fructose, ‘‘we don’t see those changes,’’ he said. ‘‘As a result, the desire to eat continues  it isn’t turned off.’’