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.^1-6 

There are two types of carbohydrates: simple and complex. Simple carbohydrates are made of one or two sugar molecules. Complex carbohydrates are made of multiple sugar molecules, called 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 carbohydrates. 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 is the high-fat oils, butters, and cheeses that really pack in the calories. 

The quality of the carbohydrates you eat also plays a role in weight gain. A diet high in refined carbohydrates can also lead to higher calorie consumption and weight gain, as these foods are less filling and less nutrient-dense compared to complex carbohydrates. Simple carbohydrates, such as added sugars have been associated with greater weight gain, while complex carbohydrates, such as those found in whole grains and vegetables, are associated with less weight gain.⁷ For example, 1 tablespoon of sugar has about the same number of calories as a small apple. The apple is going to offer more fiber, nutrients, and satisfaction compared to a spoonful of sugar. The type of carbohydrate (complex or simple) matters when it comes to weight gain.

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 daily calories from animal protein with vegetable protein, participants decreased diabetes risk by 23%.⁸

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.⁹ 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.

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

Although some studies have linked low-carb diets to short-term weight loss, it is not a good long-term solution for health and weight maintenance.^10-11 Not only is it difficult to sustain long term, but studies show that limiting and 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 weight loss long-term and .^12-13