Soy’s Potential for Weight Loss in Postmenopausal Women

Body weight is one of the most basic issues of human life. Self-esteem, acceptance among peers– and perhaps lifelong success or failure—are, unfortunately, all tied to our physical appearance. Medically speaking, not all overweight people are obese. Obesity is defined as weight that exceeds 15 percent of normal weight for height and body type. “Morbid” obesity exceeds 20 percent of optimum weight. An obese or overweight person is at high risk for a number of serious health problems, including heart disease, high blood pressure, stroke, varicose veins, dementia, psychological stress, depression, osteoarthritis, high cholesterol, and diabetes. The detrimental health effects of obesity are more than just a matter of weighing too much. Body composition–the amount of fat in the body compared to the amount of lean muscle–is also important. Body mass index (BMI) is associated with overall mortality.

Soy Isoflavones are a dietary supplement derived from soybeans containing phytoestrogens. These weak estrogens are chemically similar in structure to naturally produced estrogen hormones. Isoflavones are found in soy foods both with and without a sugar molecule attached. The two primary isoflavones in soybeans are daidzein and genistein and their respective glucosides, genistein and daidzein. Soy foods typically contain more genistein than daidzein, although this ratio varies among the different soy products. In cultures where soy products are consumed in abundance, women’s health problems, certain cancers, and cardiovascular disease are reported to be less prevalent.

A double-blinded controlled trial was performed to determine the effect of soy supplementation on abdominal fat, glucose metabolism and circulating inflammatory markers. Researchers recruited 39 obese postmenopausal women to take a soy supplement which contained 20 grams of soy protein and 160 milligrams of soy isoflavones or a casein placebo without isoflavones. Thirty-three women completed the study and were analyzed at baseline and at 3 months. The results were women given soy supplementation experienced a 7.5 percent reduction in abdominal fat, compared to 9 percent more abdominal fat in the placebo group. No differences were observed between the two groups for glucose metabolism, C-reactive protein, tumor necrosis factor-alpha, leptin or adiponectin. The authors of this study also reported that Caucasians primarily lost visceral fat (fat surrounding the organs in the abdominal cavity) while African Americans primarily lost total body fat. In conclusion, soy supplementation was found to reduce abdominal fat in obese postmenopausal women.1

Source: American Journal of Obstetrics Gynecology

1 Christie DR, Grant J, Darnell BE, et al. Metabolic effects of soy supplementation in postmenopausal Caucasian and African American women: a randomized, placebo-controlled trial. Am J Obstet Gynecol. 2010.