Dietary Supplement. Phase 2 starch neutralizer. 500 mg. Source Naturals Carbohydrate Blocker contains Phase 2 white kidney bean extract. Phase 2 works by slowing down the digestion of starch by inhibiting alpha - amylase, and enzyme that breaks down starch to be more fully absorbed by the body. Carbohydrate Blocker may help support weight loss when used in conjunction with the maximum metabolism weight loss plan (included). (These statements have not been evaluated by the food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.)