I am quoting from Dr. Atkins New Diet Revoultion, chapter 9, Facts and Fallacies, fallacy # 7..."There is now overwhelming scientific evidence that gallstones are formed when fat intake is LOW. In a study that examined the effects of a diet that provided 27 grams of fat per day, gallstones developed in thirteen percent of the participants. The reason is that the gallbladder will not contract unless fat is taken in, and if it doesn't contract, a condotion called biliary stasis devolps and the bile salts crystallize into stones. Our gallbladders need to be kept active to prevent stones. It is not uncommon to find gallstones in people who are obese, although the gallstones may not be causing discomfort. People with exsisting stones may, however, have trouble with high fat meals. If you are one of these people you may have to slowly increase the level of fat yopu eat according to your own tolerance-meaning, how you feel. So anyone who tells you they started doing Atkins and two weeks later developed gallstones doesn't fully understand the medical situation."