The present invention relates to a pharmaceutical composition for prevention or treatment of metabolic disease, comprising Bacteroides acidifaciens as an effective ingredient. In addition, the present invention relates to a composition for fat oxidation or DPP-4 inhibition, comprising Bacteroides acidifaciens as an effective ingredient. Further, the present invention relates to a transformant which exhibits a thin phenotype, and in which Atg7 gene is deleted from dendritic cells.