Last week sciencenews.org reported this really scary story about how junk food alters the pleasure sensors in rats' brains causing them to act the same as rats addicted to heroin. According to a study by the Scripps Research Institute:

After just five days on the junk food diet, rats showed “profound reductions” in the sensitivity of their brains’ pleasure centers, suggesting that the animals quickly became habituated to the food. As a result, the rats ate more food to get the same amount of pleasure. Just as heroin addicts require more and more of the drug to feel good, rats needed more and more of the junk food. “They lose control,” Kenny says. “This is the hallmark of addiction.”

If that's not gross enough, it continues:

To see how strong the drive to eat junk food was, the researchers exposed the rats to a foot shock when they ate the high-fat food. Rats that had not been constantly exposed to the junk food quickly stopped eating. But the foot shock didn’t faze rats accustomed to the junk food — they continued to eat, even though they knew the shock was coming.

Throw this on the pile of scientific studies that tell us upsetting things we already know but pretend we don't. Now I'm sad. Sad and hungry.

Hat tip to grist.org