Mayo Clinic Health Library

Carbohydrates: How carbs fit into a healthy diet

Updated: 02-08-2011

Carbohydrates often get a bad rap, especially when it comes to weight gain. But carbohydrates aren't all bad. Because of their numerous health benefits, carbohydrates have a rightful place in your diet. In fact, your body needs carbohydrates to function well. But some carbohydrates may be better for you than others. Understand more about carbohydrates and how to choose healthy carbohydrates.

Understanding carbohydrates

Carbohydrates are a type of macronutrient found in many foods and beverages. Most carbohydrates are naturally occurring in plant-based foods, such as grains. Food manufacturers also add carbohydrates to processed foods in the form of starch or added sugar. The most basic carbohydrate is a sugar molecule, which joins together one or two units of carbon, hydrogen and oxygen. Other carbohydrates contain three or more units of the carbon-hydrogen-oxygen trio.

Common sources of naturally occurring carbohydrates include:

  • Fruits
  • Vegetables
  • Milk
  • Nuts
  • Grains
  • Seeds
  • Legumes

Types of carbohydrates

There are three main types of carbohydrates:

  • Sugar. Sugar is the simplest forms of carbohydrates. Sugar occurs naturally in some foods, including fruits, vegetables, milk and milk products. Sugars include fruit sugar (fructose), table sugar (sucrose) and milk sugar (lactose).
  • Starch. Starch is made of sugar units bonded together. Starch occurs naturally in vegetables, grains, and cooked dry beans and peas.
  • Fiber. Fiber also is made of sugar units bonded together. Fruits, vegetables, whole grains, and cooked dry beans and peas are among foods that are naturally rich in fiber.

More carbohydrate terms: Net carbs and glycemic index

You may see terms such as "low carb" or "net carbs" on some products, or promoted by some diet programs. But the Food and Drug Administration doesn't regulate these terms, so there's no standard meaning. Net carbs is typically used to mean the amount of carbohydrates in a product excluding fiber or excluding both fiber and sugar alcohols.

You've probably also have heard talk about the glycemic index. The glycemic index classifies carbohydrate-containing foods according to their potential to raise your blood sugar level. Many healthy foods, such as whole grains, legumes, vegetables, fruits and low-fat dairy products, are naturally low on the glycemic index. Weight-loss diets based on the glycemic index typically restrict foods with a relatively high glycemic index ranking, such as potatoes and corn. However, there also are health benefits from these foods, so you don't necessarily have to eliminate them from your diet.

How many carbohydrates do you need?

The 2010 Dietary Guidelines for Americans recommends that carbohydrates make up 45 to 65 percent of your total daily calories. So, if you get 2,000 calories a day, between 900 and 1,300 calories should be from carbohydrates. That translates to between 225 and 325 grams of carbohydrates a day.

You can find the carbohydrate content of packaged foods by reading the Nutrition Facts label. The Nutrition Facts label shows total carbohydrates, which includes starches, fiber, sugar alcohols, and naturally occurring and added sugars. It may also list total fiber, soluble fiber and sugar separately. You may also be able to find nutrient calculators online or find information on a manufacturer's website.

Carbohydrates and your health

Despite their bad rap, carbohydrates are vital to your health for a number of reasons.

Providing energy
Your body uses carbohydrates as its main fuel source. Sugars and starches are broken down into simple sugars during digestion. They're then absorbed into your bloodstream, where they're known as blood sugar (glucose). From there, the glucose enters your body's cells with the help of insulin. Some of this glucose is used by your body for energy, fueling all of your activities, whether it's going for a jog or simply breathing. Extra glucose is stored in your liver, muscles and other cells for later use or is converted to fat.

Protecting against disease
Some evidence shows that whole grains and dietary fiber from whole foods helps reduce your risk of cardiovascular diseases. Fiber may also protect against obesity and type 2 diabetes. Fiber is also essential for optimal digestive health.

Controlling weight
Evidence shows that eating plenty of vegetables, fruits and whole grains can help you control your weight. Their bulk and fiber content aids weight control by helping you feel full on fewer calories. Contrary to what some weight-loss diets claim, very few studies show that a diet rich in healthy carbohydrates leads to weight gain or obesity.

Choosing carbohydrates wisely

Carbohydrates are an essential part of a healthy diet, and they also provide many important nutrients. Still, not all carbs are created equal. Here's how to make healthy carbohydrates work in a balanced diet:

  • Emphasize fiber-rich fruits and vegetables. Aim for whole fresh, frozen and canned fruits and vegetables without added sugar. They're better options than are fruit juices and dried fruits, which are concentrated sources of natural sugar and therefore have more calories. Also, whole fruits and vegetables add fiber, water and bulk, and help you feel fuller on fewer calories.
  • Choose whole grains. All types of grains are good sources of carbohydrates. They're also rich in vitamins and minerals and naturally low in fat. But whole grains are healthier choices than are refined grains. Whole grains are better sources of fiber and other important nutrients, such as selenium, potassium and magnesium. Refined grains go through a process that strips out certain parts of the grain — along with some of the nutrients and fiber.
  • Stick to low-fat dairy products. Milk, cheese, yogurt and other dairy products are good sources of calcium and protein, plus many other vitamins and minerals. Choose the low-fat versions, though, to help limit calories and saturated fat. And beware of dairy products that have added sugar.
  • Don't forget beans and legumes. Legumes — beans, peas and lentils — are among the most versatile and nutritious foods available. Legumes are typically low in fat, contain no cholesterol, and are high in folate, potassium, iron and magnesium. They also have beneficial fats, and soluble and insoluble fiber. Because they're a good source of protein, legumes can be a healthy substitute for meat, which has more saturated fat and cholesterol.
  • Limit added sugars. Added sugar probably isn't harmful in small amounts. But there's no health advantage to consuming any amount of added sugar. In fact, too much added sugar, and in some cases naturally occurring sugar, can lead to such health problems as tooth decay, poor nutrition and weight gain.

So choose your carbohydrates wisely. Limit foods with added sugars and refined grains, such as sugary drinks, desserts and candy, which are packed with calories but low in nutrition. Instead, go for whole grains and fruits and vegetables.

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