Starting from previous observations in clinical studies of male osteoporosis of our research group, in which an inverse relationship was found between fat mass and bone mass, the present project wishes to examine the effects of adipose tissue on the bone, by means of further animal experimental work. The mechanism of this inverse relationship is not completely known, where two hypotheses will be investigated. (1) The inverse relationship between bone and adipose tissue may be mediated by adipokines, or a modified steroid metabolism. This will be the expression of steroid metabolizing enzymes, and adipokines, as well as their activity are studied in the vetweefstel in relation to muscle and bone mass. (2) The inverse relationship may also result from a modified early fetal programming by environmental factors. Here, the effects of specific interventions during fetal life, in particular, caloric restriction or in utero androgen exposition, be verified on the bone size and bone density, as well as the effects on the expression of growth factors in muscle and fat tissue.