Does HFCS or unlimited access make people fat?

Washington Post blogger Jennifer LaRue Huget reported on a recent Princeton University study that compared the effects on lab rats of access to sucrose or high-fructose corn syrup (HFCS) twelve hours or twenty-four hours a day.  Results showed that the rats who drank HFCS were heavier than matched controls who drank sucrose.  Food Politics blogger Marion Nestle criticized the research, saying the results are inconsistent and questionably significant. 

Nevertheless, the biggest gainers were the rats with 24/7 access to unlimited chow and HFCS.  Surprised?

Perhaps the effects observed were due to overconsumption of highly palatable foods, which led to a worsening deficit in neural reward circuits of the brain.  This reward hyposensitivity, described in a Nature Neuroscience study published online yesterday, describes the creation of compulsive eating behavior as similar to the development of drug addiction.