The present invention discloses a transformant for weight loss and lipid reduction, which is obtained by recombining and substituting human oxyntomodulin gene into thymidylate synthase gene of L.lactis genome. Wherein the recombinant substitution is homologous recombination by artificially synthesizing gene sequences, making the sequence flanking the human oxyntomodulin gene derived from the homologous sequences of thymidylate synthase gene in the L.lactis genome, then the gene fragments are electroporated into L.lactis, to carry out homologous recombination. The transformant in the invention is to constitutively express oxyntomodulin, which does not contain antibiotic resistance gene. The transformant can achieve the effects of weight loss, blood lipid reduction, and blood glucose reduction. Thus it can be used for the preparation of drugs for the treatment of obesity, diabetes, and dyslipidemia.
