It has been identified that people with lower serum GH has higher prevalence of NAFLD and obesity,9,10 and Laron syndrome patients caused by GHR mutation also develop NAFLD.11 Although the association of GH signaling with metabolic diseases has been proposed previously, GH’s functional roles especially that involved in the host–gut microbiota interaction are still undefined. Here, GH1 is linked to obesity due to melanocortin 4 receptor deficiency.