Secondly, chitosan might increase the viscosity of the intestinal contents. It has been generally accepted that the anti-fatty effects of chitosan originate from its unique fat-binding properties. Dietary chitosan dissolves in the stomach, emulsifying fat and forming a gel, which binds with the fat in the intestine (Gades and Stern, 2003; Zeng et al., 2008; Zhang et al., 2008), increasing the viscosity of the intestinal contents and the unstirred layer in the intestine and slowing nutrient diffusion, which resulted in a highly effective increase in the excretion of fat (Santas et al., 2012).