the subject matter of the invention is a functional population of human brown adipocytes , in which the expression of ucp1 , cidea , cpt1b and bc12 is higher , the expression of bax is lower and the expression of ppar - alpha , pgc - 1alpha , pgc - 1 beta and prdm16 is similar compared with the corresponding expressions of a population of human white adipocytes . the invention also relates to a method for differentiation of hmads cells into the functional population of human brown adipocytes , to a method for conversion of a population of human white adipocytes into the functional population of human brown adipocytes , and also to a method of screening for molecules capable of modulating the bodyweight in an individual .