Low protein diets produce divergent effects on energy balance.
Diets deficient in protein often increase food consumption, body weight and fat mass; however, the underlying mechanisms remain poorly understood. We compared the effects of diets varying in protein concentrations on energy balance in obesity-prone rats. We demonstrate that protein-free (0% protein calories) diets decreased energy intake and increased energy expenditure, very low protein (5% protein) diets increased energy intake and expenditure, whereas moderately low protein (10% protein) diets increased energy intake without altering expenditure, relative to control diet (15% protein). These diet-induced alterations in energy expenditure are in part mediated through enhanced serotonergic and β-adrenergic signaling coupled with upregulation of key thermogenic markers in brown fat and skeletal muscle. The protein-free and very low protein diets decreased plasma concentrations of multiple essential amino acids, anorexigenic and metabolic hormones, but these diets increased the tissue expression and plasma concentrations of fibroblast growth factor-21. Protein-free and very low protein diets induced fatty liver, reduced energy digestibility, and decreased lean mass and body weight that persisted beyond the restriction period. In contrast, moderately low protein diets promoted gain in body weight and adiposity following the period of protein restriction. Together, our findings demonstrate that low protein diets produce divergent effects on energy balance.
Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.|Gastrointestinal Research Group, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, T2N 4N1, Canada.
Adel
A
Pezeshki
Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.
Rizaldy C
RC
Zapata
Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.
Arashdeep
A
Singh
Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.
Nicholas J
NJ
Yee
Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.|Gastrointestinal Research Group, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, T2N 4N1, Canada.
Prasanth K
PK
Chelikani
D002001:Adipose Tissue, Brown / Q000378:metabolism; D000818:Animals; D018753:Diet, Protein-Restricted / Q000009:adverse effects*; D002149:Energy Intake; D004734:Energy Metabolism; D005346:Fibroblast Growth Factors / Q000097:blood / Q000235:genetics; D005786:Gene Expression Regulation; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D009765:Obesity / Q000209:etiology / Q000378:metabolism* / Q000503:physiopathology / Q000517:prevention & control; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D022722:Thermogenesis
C414620:fibroblast growth factor 21; D005346:Fibroblast Growth Factors