The gnc total lean phase 2 carb controller contains clinically studied white kidney bean extract to help fuel your weight management goals. This supplement contains extract from phaseolus vulgaris, also known as white kidney bean extract, and may minimize the caloric impact of carbohydrates. White kidney beans produce an alpha amylase inhibitor, which might curb the enzymes that aid in the digestion of carbohydrates, thereby slowing their absorption. Alpha amylase may also play a role in the digestion of starches.