A study published in Endocrinology suggests active isoflavone compounds found in soy, specifically, genistein, may help us stay lean by causing us to produce fewer and smaller fat cells. In this study, laboratory animals eating diets that provided between 500-1500 ppm (parts per million) of genistein created less and smaller fat cells than the animals eating regular chow. In the animals eating soy, decreases in fat production were significant, ranging from 37% to 57% less than the amount of fat produced by mice given standard chow.
In human terms, a comparable amount of genistein to that the animals were given could easily be consumed by simply including traditional soyfoods as part of a healthy whole foods eating plan since most traditional soyfoods, such as tofu, soy milk, tempeh, and miso, are rich sources of isoflavones, providing about 30 to 40 milligrams per serving.