The invention relates to the use as a drug or medical nutritional product in humans to treat a pathological dysbiosis and/or to prevent or treat at least one derived metabolic disease chosen from among excess weight with comorbidity, obesity, diabetes, heart and vascular diseases, atherosclerosis, degenerative bone disease, neurodegenerative disease, metabolism-related cancers, autoimmune diseases, steatosis, metabolic steatohepatitis, and chronic inflammatory diseases of the intestine, by increasing the Christensenella bacterial genus in the intestine, of a composition comprising a mixture of active ingredients consisting of at least: a whey hydrolysate with a molecular weight comprised between 200 and 10,000 Daltons, a whey isolate and/or a concentrate, and calcium caseinate.