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

Protein requirement has been determined at 10%-15% energy. Under dietary self-selection, rats ingest 25%-30% energy as protein and regulate FGF21 (a hormone signaling protein deficiency) to levels lower than those measured with a 15% protein (15P) diet. Our hypothesis is that if a 15P diet was indeed sufficient to ensure protein homeostasis, it is probably a too low protein level to ensure optimal energy homeostasis.

Protein-carbohydrate interaction effects on energy balance, FGF21, IGF-1, and hypothalamic gene expression in rats.

Amino acids are involved in energy homeostasis, just as are carbohydrates and lipids. Therefore, mechanisms controlling protein intake should operate independently and in combination with systems controlling overall energy intake to coordinate appropriate metabolic and behavioral responses. The objective of this study was to quantify the respective roles of dietary protein and carbohydrate levels on energy balance, plasma fibroblast growth factor 21 (FGF21) and insulin growth factor 1 (IGF-1) concentrations, and hypothalamic neurotransmitters (POMC, NPY, AgRP, and CART).

Rats Self-Select a Constant Protein-to-Carbohydrate Ratio Rather Than a Constant Protein-to-Energy Ratio and Have Low Plasma FGF21 Concentrations.

Background: Under dietary self-selection (DSS), rats ingest 25-30% of energy as protein. This high level appears to be explained by metabolic benefits related to reduced carbohydrate dependence and associated pathologies. However, the mechanisms underlying these choices remain largely misunderstood.

What does self-selection of dietary proteins in rats tell us about protein requirements and body weight control?

Omnivores are able to correctly select adequate amounts of macronutrients from natural foods as well as purified macronutrients. In the rat model, the selected protein levels are often well above the requirements estimated from the nitrogen balance. These high intake levels were initially interpreted as reflecting poor control of protein intake, but the selected levels were later found to be precisely controlled for changes in dietary protein quality and adjusted for cold, exercise, pregnancy, lactation, age, etc.

Consumption of Ultra-Processed Foods by Pesco-Vegetarians, Vegetarians, and Vegans: Associations with Duration and Age at Diet Initiation.

Background: There is a growing availability of industrial plant-based meat and dairy substitutes that can be classified as ultra-processed foods (UPFs). Very little is known about the consumption of UPFs by vegetarians.

Objective: The aim of this cross-sectional study, from the NutriNet-Santé cohort, was to describe the contribution of UPFs to different vegetarian diets, in relation to the nutritional quality of their diet, and determinants of UPF consumption, including duration and age at vegetarian diet initiation.