This is a follow-up research study to determine if there are any differences in the long-term maintenance of two diet groups, the Atkins' diet (low-carbohydrate) or the LEARN program (low-fat). The Atkins' diet continues to get a significant amount of popular attention and very little scientific evaluation. Due to the small amount of scientific data to support a low-carbohydrate diet and given the wide spread use of this type of diet, it is important to evaluate the long-term safety and effectiveness of the Atkins' diet.