Background: Protein is an indispensable component within the human diet. It is unclear, however, whether behavioral strategies exist to avoid shortages.
Objective: The objective was to investigate the effect of a low protein status compared with a high protein status on food intake and food preferences.
Design: We used a randomized crossover design that consisted of a 14-d fully controlled dietary intervention involving 37 subjects [mean ± SD age: 21 ± 2 y; BMI (in kg/m(2)): 21.9 ± 1.5] who consumed individualized, isoenergetic diets that were either low in protein [0.5 g protein · kg body weight (BW)(-1) · d(-1)] or high in protein (2.0 g protein · kg BW(-1) · d(-1)). The diets were followed by an ad libitum phase of 2.5 d, during which a large array of food items was available, and protein and energy intakes were measured.
Results: We showed that in the ad libitum phase protein intake was 13% higher after the low-protein diet than after the high-protein diet (253 ± 70 compared with 225 ± 63 g, P < 0.001), whereas total energy intake was not different. The higher intake of protein was evident throughout the ad libitum phase of 2.5 d. In addition, after the low-protein diet, food preferences for savory high-protein foods were enhanced.
Conclusions: After a protein deficit, food intake and food preferences show adaptive changes that suggest that compensatory mechanisms are induced to restore adequate protein status. This indicates that there are human behavioral strategies present to avoid protein shortage and that these involve selection of savory high-protein foods. This trial was registered with the Dutch Trial register at http://www.trialregister.nl as NTR2491.