Carb/starch blockers are a form of dietary supplement that contain white kidney bean extracts. These extracts help block the amount of carbohydrates that your body absorbs. By reducing the amount of carbs absorbed they reduce your body’s whole day caloric intake. Many people feel that these supplements are great for people who can no resist the urge of consuming carbs/starches. Some advocates even suggest that these pills are good for diabetics, since they lower the glycemic index of the food consumed by the user.