DISGUISED PROTEIN IN LUNCH AFTER LOW-PROTEIN BREAKFAST CONDITIONS FOOD-FLAVOR PREFERENCES DEPENDENT ON RECENT LACK OF PROTEIN-INTAKE

As in the conditioning of appetite for protein in the rat, human prefe rence for and intake of a food at lunch was increased when the flavor of that food was paired with an adequate supply of protein, following a breakfast lacking in protein. Men and women rated their preferences for two flavors in tasted foods (soup and cornflour dessert) on test d ays before and after a day when one flavor was eaten in very low prote in food and another day with a different flavor eaten in food containi ng protein, but with minimal sensory differences between these foods. Subjects given a low-protein drink preload preferred the protein-paire d flavor, while those receiving a high-protein drink did not. In a sec ond experiment, preferences were measured by intake as well as ratings , and the difference in amount of protein between high- and low-protei n lunches was increased. By both measures, relative preference for hig h-protein-paired dessert flavors increased from before to after pairin g. The increase in intake preference ratio for the protein-paired flav or was abolished by a high-protein preload. Thus, people have a learni ng mechanism whereby a lack in protein intake comes to cue the selecti on of protein-rich foods that are not known to be such, and/or loading with protein might trigger avoidance specifically of a high-protein d iet.