A study out of Scripps Research Institute in Florida finds junk food is as addictive as drugs.
Researchers found when they gave rats unlimited access to candy and other junk food the pounds piled on. As the rats gained weight, eating became such a compulsion, they kept packing it in even when they knew they would receive an electric shock.
Meantime, rats fed a healthy diet with limited access to junk food knew to stop eating when they knew a shock was coming.
You can read more in Nature Neuroscience.