this is from the article:
Question 4: Do these fat rats continue to overeat even in the presence of punishment?
This is an important question to ask to make this work really relevant to the way that humans binge eat. To do this, you give a rat access to the high fat food, but you add in a painful foot shock (not one that causes damage, just short and painful). You pair the foot shock with a light. The rat will learn that the light means shock and will (presumably) stop eating. Sure enough, when the light came on, the chow rats and snack rats stopped eating. The fat rats, however, DIDN'T. Their food intake wasn't sensitive to punishment anymore, something which may indicate that they will continue to overeat even though it's bad for them. This ALSO worked when they tried it with the rats that had artificially knocked down D2 receptors, they also just kept on eating, showing that the decreased D2 receptors may have something to do with the way the rats were responding for food.
Here's a link to whole article: http://scienceblogs.com/neurotopia/2...y_the_food.php