Kidnney supplements are scam, read this:
http://www.ftc.gov/opa/2004/08/pvt.htm
Pinnacle Marketing, LLC ("Ultra Carb")
Pinnacle Marketing, LLC, based in Biddeford, Maine, marketed a purported weight loss system called "Ultra Carb" consisting of two tablets: a "carb blocker" with white kidney bean extract, chromium picolinate, and other ingredients; and a "fat blocker" with chitosan. Pinnacle's advertisements claimed that Ultra Carb would block the absorption of carbohydrates and fat in the body, enabling users to lose a substantial amount of weight - as much as 20 pounds and two to three dress or pant sizes in one month - without diet or exercise. Pinnacle advertised Ultra Carb in radio ads broadcast in metropolitan areas including Los Angeles, Chicago, and Boston; through ads in newspapers such as The Washington Post and the Detroit Free Press; in panel advertisements on television Interactive Programming Guides; and with an Internet coupon. Pinnacle sold a two-month supply of Ultra Carb directly to consumers for $99.95, plus shipping and handling.