Issues in Nutrition: Carbohydrates.

Carbohydrates include sugars, starches, and dietary fibers. Resistant starches resemble fiber in their behavior in the intestinal tract, and may have positive effects on blood glucose levels and the gut microbiome. Fibers are classified as soluble and insoluble, but most fiber-containing foods contain a mixture of soluble and insoluble fiber. Soluble fiber has been shown to lower low-density lipoprotein cholesterol levels. Many artificial sweeteners and other sugar substitutes are available. Most natural sources of sweeteners also are energy sources. Many artificial sweeteners contain no kilocalories in the amounts typically used. Sugar alcohols may have a laxative effect when consumed in large amounts. Glycemic index and glycemic load are measurements that help quantify serum glucose response after ingestion of particular foods. These measurements may be affected by the combination of foods consumed in a given meal, and the glycemic index may vary among individuals eating the same meal. Eating foods with a low glycemic index may help prevent development of type 2 diabetes. There is no definitive evidence to recommend low-carbohydrate diets over low-fat diets for long-term weight loss; they are equally effective.