In 3 clinical trials of overweight individuals on diets with a low glycemic load or with large amounts of fiber and whole grains, elevated fasting blood glucose before treatment indicated successful weight loss and maintenance. The American Journal of Clinical Nutrition analysis included information from the Diet, Obesity, and Genes trial; the OPUS Supermarket intervention trial; and the Nutrient-Gene Interactions in Human Obesity trial. For individuals with prediabetes, consuming vegetables, fruits, and wholegrains was effective for weight loss and could potentially improve diabetes markers. A diet rich in healthy fats from plant sources was most effective for patients with type 2 diabetes.