Cephalic phase responses and appetite.

The current food supply in many parts of the world differs substantially from that which existed during most of human evolution. It is characterized by a high variety of palatable foods with high energy density and low fiber content. Many foods can be eaten very quickly, and there is not always congruency between the sensory properties of the food and the subsequent metabolic consequences of its ingestion, (e.g., as in the consumption of artificially sweetened foods). It is not presently known how the human body copes with this incongruent food environment in terms of short-term satiety responses and long(er)-term regulation of food intake. Cephalic phase responses (CPRs) are innate and learned physiological responses to sensory signals that prepare the gastrointestinal tract for the optimal processing of ingested foods. CPRs could be affected by inconsistencies in the associations between sensory signals and subsequent post-ingestive consequences. Reviewed here are the available data on how CPRs affect the control of food intake.