RETN and immune system disorder: Search words were "obesity," "fatty acids," "adipose tissue," "inflammatory markers," "macrophages," "immune cells," "leptin," "resistin," and "visfatin." The review yielded a total of 93 articles that emphasized the description of obesity as low-grade chronic inflammation or immune disease, its inflammatory markers, specifically resistin and visfatin, and the prevalence and effect of fatty acids on inflammation.