Food deprivation increases the rat's preference for a fatty flavor over a sweet taste

Previous research indicates that food deprivation increases the rat's preference for high-fat over low-fat foods. Since these foods differ in their flavors and post-ingestive effects, both factors may be implicated. The present study investigated preferences in food deprived and non-deprived rats using non-nutritive mineral oil emulsion (MO) and saccharin solution (SAC), which have a fatty flavor and sweet taste, respectively. The deprived rats consumed more MO than SAC in one- and two-bottle tests, while the non-deprived rats ingested as much SAC as MO in one-bottle tests and preferred SAC in two-bottle tests. Several aspects of the data suggest that the deprivation-related shift in preference between MO and SAC was determined by changes in long-term energy balance. A follow-up conditioning experiment discarded the possibility that the observed preference shift was related to differential reinforcing effects of the two substances. In conclusion, long-term food restriction increases the preference for an oily flavor over a sweet taste via a mechanism that does not involve nutritive feedback. It remains to be determined to what extent this alternation in flavor preference influences food selection when post-ingestive nutritive feedback can influence food choice.