Researchers at Scripps Research Institute in Florida have conducted an experiment in which rats have the same brain reactions to fatty foods as they have to dependency causing drugs. The scientists divided their rats into three groups: the first group ate a regular diet, the second had access to extremely fatty foods for one hour day, and the third group was given no limits access to all the fatty food they could consume.
"Inside their little brains, the junk-food eating rats developed a big problem. Just like drug takers, the rats needed a bigger fix of junk food over time to maintain their pleasure. So they kept on eating, and kept on getting fatter."
The researchers "did all sorts of other experiments to tease apart the connection between overeating and the pleasure response. Bottom line: eating a lot of junk food makes you want to eat more junk food."