MUC5AC and obesity due to melanocortin 4 receptor deficiency: These include Akkermansia, Bacteroides, and Prevotella. Recent studies have highlighted a direct role for Akkermansia, a mucin-degrading bacterium, in obesity, where treatment of mice with Akkermansia has been shown to reduce high fat diet (HFD)-induced metabolic disorders including fat mass gain, metabolic endotoxemia, adipose tissue inflammation, and insulin resistance (Everard et al., 2013).