"You Say it's Liking, I Say it's Wanting …". On the difficulty of disentangling food reward in man.

According to the influential theory of Berridge (1996, 2009), food reward comprises two components: food 'liking' and 'wanting', with 'liking' referring to the pleasure derived from eating a given food and 'wanting' referring to appetitive motivation. Animal research shows that these two components have separate neural correlates. In examining reward driven eating in man, researchers have thus begun to develop interest in indicators of 'liking' and 'wanting'. But validating 'liking' and 'wanting' requires the dissociation of these components when theory dictates they should diverge. One such circumstance is neural sensitization as this leads to exaggerated 'wanting' without increased 'liking'. However, there are no data suggesting that such sensitization is the likely result of (over)eating. Without sensitization, one cannot determine whether task performance is indicative of true food 'liking' or 'wanting'. It is concluded that it is important to assess appetite and palatability in the study of reward driven eating, but determining whether these measurements reflect either food 'wanting' or food 'liking' is not.