Whey protein isolate protects against diet-induced obesity and fatty liver formation

Abstract We investigated the potential of a novel whey protein isolate (WPI) rich in lactoperoxidase, lactoferrin, growth factors and immunoglobulins, in the prevention and treatment of diet-induced obesity in C57Bl/6J mice. Compared with casein, WPI dose-dependently enhanced weight loss and decreased body fat content during energy restriction. WPI decreased hepatic S6 ribosomal protein phosphorylation and increased SIRT3 expression. WPI did not influence energy intake, apparent fat digestibility, or adipose tissue inflammation. Compared with casein, WPI dose-dependently prevented weight regain and protected against the development of fatty liver formation during ad libitum feeding after weight loss. WPI also modestly improved glucose tolerance. It was concluded that compared with casein, a diet based on WPI as protein source significantly improved outcome of weight loss and subsequent weight regain in high-fat-fed C57Bl/6J mice. The effects are mediated, at least partly, via inhibition of mTOR nutrient sensing pathway and activation of SIRT3 in the liver.