Moreover, heat-killed B420 could not enhance the preventive efficacy of <i>Cordyceps militaris</i> against obesity caused by the HFD.<h4>Conclusions</h4>The metabolites of live B420 and <i>Cordyceps militaris</i>-derived metabolites in the gut microbiota collaboratively promoted the production of mucin 2. The gene discussed is MUC2; the disease is obesity due to melanocortin 4 receptor deficiency.