ASN Community Forum
The ability to sense and respond to nutrient restriction is one of the most essential physiological functions in biology. Free-feeding animals often face a complex nutritional landscape where individual food sources vary in macronutrient content, energy density, palatability, and availability. Effectively navigating this nutritional landscape requires choices that maximize nutrient intake while minimizing procurement cost. Dietary protein is essential for health and growth, and the restriction of protein intake is known to induce adaptive changes in metabolism and behavior. Our work suggests that the metabolic hormone FGF21 is the essential mediator of this adaptive response, with FGF21 acting in the brain to coordinate changes in growth, energy expenditure, glucose homeostasis, and food choice during protein restriction. FGF21 appears to be unique among nutritional cues in this role as a signal of macronutrient imbalance.