The Carbohydrate Advantage

Carbohydrates are essential for good health, as they are the main fuel for the brain and muscles. Studies show that those who eat the most carbohydrates—especially those found in whole, natural foods like beans, whole grains, fruits, and vegetables—have a lower risk for heart disease, type 2 diabetes, and obesity.

There are two types of carbohydrates: simple and complex. Simple carbohydrates are made of one or two sugar molecules. Complex carbohydrates are polysaccharides and include starch and fiber.

For optimal health, choose complex carbohydrates. Complex carbohydrates, found mostly in whole plant foods, maintain their natural fiber and fuel your body with the energy it needs. Examples include beans, oatmeal, 100% whole-wheat bread, quinoa, barley, potatoes, sweet potatoes, and many other plant foods. These foods are also naturally rich in vitamins, minerals, and phytochemicals. About three-quarters of daily calories should come from healthful carbohydrates.

Limit simple carbs, such as added sugars, syrups (even agave), and white flour. These provide quick energy but have been stripped of nutrients and fiber. The exception is fruit. Sugar in fruit comes with health-boosting fiber, vitamins, minerals, and phytochemicals. Be sure to include plenty of colorful fruits in your diet.

Can carbohydrates lead to weight gain?

The idea that carbohydrates will lead to weight gain is a common misconception, but gram for gram, fat contains more than twice the calories of carbs. One gram of fat—from beef, fish, or oil—has 9 calories. Compare that to 1 gram of carbohydrate from potatoes, bread, or beans, which has only 4 calories. You may also notice that carbs become less healthy based on what we add to them: Potatoes are often deep-fried in oil to make french fries—and pizza, bread, and pasta are often just vehicles for butter and cheese. It’s the high-fat oils, butters, and cheeses that really pack in the calories.

Do carbohydrates cause diabetes?

A diet emphasizing healthful carbohydrates—vegetables, fruits, whole grains, and legumes—and avoiding animal products helps prevent diabetes and improves its management when it has been diagnosed. One study of more than 200,000 participants found that consuming large amounts of animal protein increased diabetes risk by 13%. But by simply replacing 5% of animal protein with vegetable protein—including carbohydrates like potatoes and grains—participants decreased diabetes risk by 23%. In 2006, the Physicians Committee’s research team partnered with the George Washington University and the University of Toronto to test a low-fat, plant-based diet against a standard diabetes diet that limited carbohydrates recommended by the American Diabetes Association at the time. Participants in the plant-based group lowered hemoglobin A1C by 1.2 points, which was three times greater than the ADA group. Learn more about healthful plant-based diets for diabetes.

Although glucose is an important fuel for the body, there is no physiological need for added sugars, which can contribute to weight gain, diabetes, and other health problems. Avoiding added sugars and heavily processed carbohydrates is a helpful step, and it should be taken in addition to a healthful plant-based diet.

What are the health effects of eating a low-carb diet? 

Studies show that avoiding carbohydrates can harm your health. Many low-carb diets, including the keto diet, severely limit or eliminate most fruits, starchy vegetables, whole grains, and legumes (beans, lentils, and split peas)—foods that are packed with nutrition. As a result, low-carbohydrate diets are often low in nutrients found in these foods, such as thiamine, folate, vitamin A, vitamin E, vitamin B6, calcium, magnesium, iron, and potassium. Without vitamin supplements, those on low-carb diets are at risk of multiple deficiencies. Low-carb diets are often low in fiber and are also typically high in saturated fat and cholesterol, known to cause further health problems. Studies link low-carb diets to an increased risk for heart disease and early death.