http://www.sciencedirect.com/science/article/pii/S0091305710...
Reply by the Corn Refiners Association:
http://www.corn.org/princeton-hfcs-study-errors.html
Thermodynamics question: They were holding energy inputs constant in the system. Stored energy was not constant. What third variable could have been responsible for the difference? Rhymes with input.
The study's conclusions are misleading. The total intake from food and the sweetened water were not matched for calories. The only thing matched for calories was the amount of sweetened water; rats were allowed to eat as much food as they want. They then drew all of these conclusions that aren't directly related to HFCS, but related to the fact that the rats were overeating.
It's still an interesting conclusion, but really the only thing they concluded was that rats consuming HFCS ate more food than rats consuming sugar. All of the other negative effects cannot be pinned on HFCS.