This comprehensive review, published in the November issue of Obesity Reviews, examines current research on animals, human populations, and clinical trials related to soy protein and weight control. Researchers sought to determine the strength of the evidence on four proposed mechanisms by which soy may aid weight control: 1) soy increases weight loss when consumed at an equal calorie level as other foods, 2) soy aids weight and fat loss by decreasing caloric intake, 3) certain soyfoods benefit glucose control and heart health during weight loss, and 4) certain soyfoods will minimize the loss of bone mass during weight loss.
The review, including results from eight human studies, finds that individuals lost equivalent amounts of weight and, in some cases, equal inches of fat around the waist, using soy protein, dairy milk meal replacements, beef or pork at equal calorie levels. This illustrates the value of soy protein in a varied diet for weight control. Findings also support the possibility that soy protein decreases short-term appetite and calorie intake. Extensive follow-up trials are needed to prove the satiety, or feeling of fullness, factor of soy protein.
Researchers also examined whether soy isoflavones reduce diabetes by stopping fat tissue buildup and enhancing fat breakdown. Limited animal trials and human studies suggest soy-based diets and isoflavones may lower blood glucose and insulin levels. If proven effective, a soy-based meal replacement could provide additional benefits to diabetics during weight reduction. Researchers confirmed soy-based diets, compared to other low-calorie diets, reduce LDL (bad) cholesterol and triglycerides and raise HDL (good) cholesterol. Findings indicate soy may reduce bone loss in women, but additional clinical trials on soy and bone loss are needed.
From the January 21, 2008, Prepared Foods e-Flash