When hungry people see or smell a favorite food, their brain reacts in a similar way to brains of drug addicts upon seeing a drug. The regions of the brain that light up on brain scans when people are presented with a favorite food are the same areas that are associated with addiction. This means that you really can be addicted to certain foods and, as I've been saying for years, I believe a substantial number of Americans are addicted to sugar and grains. This study brings up an interesting point in that the results explain just how hard it can be for people to resist junk food when they are exposed to it constantly in the form of advertisements, candy displays and even food TV channels. They say that the brain region associated with addiction is so sensitive to food stimuli that it is likely contributing to the current obesity epidemic.
NeuroImage April 2004;21(4):1790-7