Abstract: The present invention is concerned with a method of controlling the plasma genistein concentration in mammals in order to avoid activation of the peroxisome proliferator-activated receptor ? (PPAR?), said method comprising the steps of: a. assessing the genistein blood serum concentration of the mammal; b. if needed, administering to said mammal a genistein component in an amount sufficient to maintain the genistein blood serum concentration at a level between 0.02 and 3 ?M during at least 8 hours, preferably at least 16 hours of each day; c. repeating steps a. and b. during a period of at least 30 days with intervals of no more than 3 days. The present method is particularly suited for preventing obesity and diseases or conditions in which bone tissue is lost.