All carbohydrates aren't alike. While some foods in this group are extremely healthy, others are extremely unhealthy. Choose your carbohydrates carefully. Fruits, vegetables and whole grains are beneficial for wellness while sugary foods and refined grains are detrimental.
Types of Carbohydrates
The American Diabetes Association says carbohydrates come in three types: starches, sugars and fiber.
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Starches, also called complex carbohydrates, include lentils, peas and beans, along with vegetables like potatoes and corn. Other food sources of starches are grains, which can be subdivided into two categories: whole grains and refined grains, notes the ADA.
Whole grains involve unrefined grains like brown rice, oats, barley and baked goods made of 100 percent whole-grain flours. These grains are much higher in vitamins and minerals than refined grains, which include white rice and baked goods made with white flour such as white bread, pasta, crackers, cookies and cake.
Sugars encompass the natural sugars found in milk and fruit, as well as added sugars such as molasses, honey, brown sugar, white sugar, maple syrup and high-fructose corn syrup. Manufacturers use sugars from the latter category in a host of processed foods.
Fiber comes from the indigestible portion of plant foods. Sources include beans, fruits, vegetables, nuts and whole grains. No animal foods contain fiber.
Benefits of Healthy Carbohydrates
Carbohydrates have an array of health benefits, reports the Mayo Clinic. Most important is that they're the body's main source of fuel. A November 2014 article in Advances in Nutrition explains that carbohydrates supply glucose, which is the primary energy source of the brain, central nervous system and red blood cells. Glucose is also stored as glycogen in the muscles.
According to Harvard T.H. Chan School of Public Health, a diet plentiful in fruits and vegetables offers disease prevention. The foods can reduce blood pressure, prevent some types of cancer, improve blood sugar and curb appetite. In addition, they reduce the likelihood of heart disease, strokes, eye disorders and digestive maladies.
Whole grains contain bran, the fiber-rich outer layer of grain kernels, which is plentiful in vitamins, minerals and phytochemicals. Bran and fiber slow the breakdown of starch into glucose, which promotes a steady level of blood sugar rather than causing sharp spikes.
Fruits contain simple sugars, such as sucrose, fructose and glucose, which are associated with obesity. However, an October 2016 study published in Nutrients found that, instead of promoting weight gain, they have an anti-obesity effect. The authors attribute this benefit to the food's content of phytochemicals and fiber.
Aside from fruits, vegetables and whole grains may also help control weight, says the Mayo Clinic. Their fiber content promotes a feeling of fullness, which leads to lower calorie consumption.
Fiber also promotes regular bowel movements, lowers cholesterol and prevents blood clot formation that can lead to a stroke or heart attack. A mechanism of action that may underlie the effects of fiber is that it nourishes the beneficial bacteria in the gut, which has broad implications for wellness, notes the Physicians Committee for Responsible Medicine.
Read more: List of Healthy Carbs
Effects of Unhealthy Carbohydrates
Foods and beverages containing added sugar or refined grains are simple or unhealthy carbohydrates. These include sodas, fruit drinks, candy, white rice, white bread, pastries and desserts. It's best to limit dietary sources of sugar and refined flours.
Because simple carbohydrates lack fiber to slow the digestion process, they're digested quickly, says the American Heart Association. This explains why people get a sudden energy spurt followed by fatigue after consuming one of these foods. Since the foods are high in calories but lacking in nutrients, they also lead to weight gain.
Eating a diet high in refined grains like white bread increases symptoms of Type 2 diabetes. A November 2014 study featured in Mediators of Inflammation found consumption of refined grains is a risk factor for insulin resistance, which is a primary sign of the disease. In a March 2014 study published in the British Journal of Nutrition, researchers discovered that high consumption of white rice and noodles was linked to insulin resistance and high blood sugar.
Refined carbohydrate consumption also may be harmful to heart health. A December 2017 study published in Open Heart concluded that a diet high in refined carbohydrates and sugar may increase the risk of coronary heart disease.
How Much Carbohydrate to Eat
The Dietary Guidelines for Americans from the Office of Disease Prevention and Health Promotion recommend that carbohydrates comprise 45 to 65 percent of your daily caloric intake. This means that within a 2,000-calorie diet, 900 to 1,300 calories should come from carbohydrates.
Men and women should eat 2 cups of fruit per day, recommends the United States Department of Agriculture. The Cleveland Clinic advocates eating fruit rather than drinking fruit juice, even 100 percent fruit juice, to get the fiber content. Juice drinks that aren't labeled "100 percent fruit juice" have a high amount of added sugar. Fruit that is processed into jellies and jams contains large quantities of high fructose corn syrup.
Vegetables come in five categories: dark green; red and orange; peas and beans; starchy; and a category referred to as "other." Examples of dark green vegetables include broccoli, spinach, kale and intensely green lettuce varieties; while examples of red and orange vegetables include carrots, sweet potatoes and winter squash. Vary your vegetable intake, so you'll get some from each of the five types within a week, advises the USDA. The daily recommended intake is 2 to 2 1/2 cups for women and 2 1/2 to 3 cups for men.
Read more: The Effects of Eating Too Many Carbs
The USDA states that half of your daily intake of grains should come from whole-grain foods. This means that, of the daily recommended 5 to 6 ounces of grains for women and 6 to 8 ounces of grains for men, 3 to 4 ounces should consist of whole grains. In general, 1 cup of cereal or one slice of bread is considered an ounce. Try to choose brown rice over white rice, and select oatmeal for breakfast rather than pastries. Look for bread labeled either 100 percent whole-wheat or 100 percent whole-grain.
- American Diabetes Association: "Types of Carbohydrates"
- Mayo Clinic: "Carbohydrates: How Carbs Fit Into a Healthy Diet"
- Harvard T.H. Chan School of Public Health: "Vegetables and Fruits"
- Nutrients: "Paradoxical Effects of Fruit on Obesity"
- Harvard T.H. Chan School of Public Health: "Whole Grains"
- American Heart Association: "Carbohydrates"
- Mediators of Inflammation: "Excessive Refined Carbohydrates and Scarce Micronutrients Intakes Increase Inflammatory Mediators and Insulin Resistance in Prepubertal and Pubertal Obese Children Independently of Obesity"
- British Journal of Nutrition: "Rice and Noodle Consumption Is Associated With Insulin Resistance and Hyperglycaemia in an Asian Population"
- Open Heart: "Markedly Increased Intake of Refined Carbohydrates and Sugar Is Associated With the Rise of Coronary Heart Disease and Diabetes Among the Alaskan Inuit"
- USDA ChooseMyPlate: "All About the Fruit Group"
- Cleveland Clinic: "Is 100 Percent Fruit Juice as Healthy as It Sounds?"
- USDA ChooseMyPlate: "All About the Vegetable Group"
- USDA ChooseMyPlate: "All About the Grains Group"
- Office of Disease Prevention and Health Promotion: "Dietary Guidelines for Americans: Appendix 7. Nutritional Goals for Age-Sex Groups Based on Dietary Reference Intakes and Dietary Guidelines Recommendations"
- Advances in Nutrition: "Carbohydrates"
- Physicians Committee for Responsible Health: "Gut Bacteria"