In a recent study conducted at the University of Alabama at Birmingham and at the University of Vermont, postmenopausal women who drank a shake containing soy protein and isoflavone versus a shake with equal amounts of casein, a milk protein without isoflavones, wound up with less abdominal fat. Participants in the three-month study drank daily shakes with equal calories, with either 20 grams of soy protein or 20 grams of casein.

“If you look at the change in total fat and the change in lean body mass, abdominal fat actually increased with the [casein] placebo and decreased with the soy group,” said Cynthia Sites, MD, the lead author of the study. Further trials are planned to determine if different amounts of soy protein or drinking fewer shakes can have the same effects.

Excess abdominal fat is associated with increased risk of cardiovascular disease and diabetes. “I recommend soy for postmenopausal women,” Sites says. “In addition to potentially reducing abdominal fat, soy may benefit the heart.”