Plasma FGF21 concentrations and spontaneous self-selection of protein suggest that 15% protein in the diet may not be enough for male adult rats

Abstract

Under dietary self-selection, rats choose to ingest 25%–30% of energy as protein, a value higher than the protein requirement (10%–15%). According to our results, this higher spontaneous intake reflects the fact that rats fed a 15% protein diet, compared with high-protein diets, tend to bind more fat and have higher concentrations of FGF21, a hormone signaling protein deficiency. A 15% protein diet appears to be sufficient for protein homeostasis but not for optimal energy homeostasis.