GCG and obesity due to melanocortin 4 receptor deficiency: In the present study, in order to determine the roles of GLP-1 in HFD-induced obesity and overcome its limitations, we constructed an engineered bacteria of MG1363-pMG36e-GLP-1 (M-GLP-1) that can constitutively secrete GLP-1 (1–37) through oral administration, and we evaluated its efficiency of alleviating obesity and potential mechanisms on obese mice induced by high fat diet (HFD) in vivo.