According to the disclosure hypoxia-mediated adipogenic inhibition involves the repression of PPAR.gamma.2 expression and its activity is a common mechanism for adipogenic inhibition by a variety of stimuli. The present disclosure relates to methods and compositions for regulating adipogenesis. The disclosure provides compositions comprising one or more DEC1/Stra13 fragments of capable of inhibiting PPAR.gamma.2 promoter activity. These fragments, e.g. the basic helix loop helix domain or amino acids 1-141, have substantially the same PPAR.gamma.2 promoter repressing activity as the full length polypeptide. The present disclosure provides methods of inhibiting adipogenesis comprising contacting a cell with a fragment of DEC1/Stra13. The invention further relates to methods and compositions of inhibiting angiogenesis in a tumor comprising contacting a tumor or tumor cell with a DEC1/Stra13 agonist.