poor little rats were actually starving, they were eating nutrient-deficient foods and their bodies were desperately trying every available option (including the brain reward system) to try to pull in some nutrients. "In the wild" high-fat and high-sugar foods are nutrient-rich, which is why just about every critter out there craves them.
Never mind food addiction, though. I'm quite concerned about my oxygen addiction. I keep trying to swear off the stuff, but the more dirty car exhaust I inhale, the more I crave oxygen! I can be taking in great lungfuls of car exhaust 20 times a minute, but I *still* feel the craving to breathe! I'm breathing and breathing and breathing, more than I usually do, but I still yearn for more breaths!
(oxygen = nutrients, car exhaust = nutrient poor food substances)
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson