The increased TNF-α, MCP-1, and iNOS expression in the liver of obese rats compared to lean rats and their decreased expression in the SPC-LIF and SPC-HIF diet-fed obese rats compared to the casein control diet-fed obese rats suggest that liver pro-inflammatory macrophage activity was increased by obesity, and the increase was attenuated by soy protein diets. Here, LIF is linked to obesity due to melanocortin 4 receptor deficiency.