KDDP is a prospective, 12-month pilot study comparing the effects of a novel lifestyle program, the Ketogenic Diet and Diabetes Demonstration Project (KDDP) to those of the National Diabetes Prevention Program (NDDP). KDDP is modeled to mimic the delivery platform of NDPP with the exception that participants in KDDP will be placed on a medically-supervised ketogenic diet, and participants in NDPP will be placed on a low fat diet. The purpose of this study is to compare the metabolic effects of the KDDP and the NDPP on glycemic control, lipid parameters, blood pressure, heart rate, weight, and coronary artery calcium scores in individuals with either type 2 diabetes or prediabetes.