What Are Complex Carbs? Simple vs Complex Carbohydrates

Author: Imani Brooks · Posted: October 23, 2026 · Updated: October 23, 2026

#complex carbs #whole grains #carbohydrates #starch

The short answerComplex carbohydrates are starches and fibers made of long chains of sugar molecules. They're found in whole grains, beans, lentils, peas and starchy vegetables like potatoes and corn. Because whole-food sources come packaged with fiber, they tend to digest more slowly than sugary foods and drinks, offering steadier energy along with vitamins and minerals.

Small ceramic bowls of uncooked oats, quinoa, brown rice, dried lentils and chickpeas arranged in a row beside two roasted sweet potatoes on a linen cloth

Complex carbohydrates are carbs made of long chains of sugar molecules, mainly starch and fiber. You’ll find them in whole grains, beans, lentils, peas and starchy vegetables like potatoes, corn and squash. Because whole-food sources come packaged with fiber, vitamins and minerals, they tend to digest more slowly than sugary foods and drinks, giving you steadier energy and keeping you full longer.

Simple vs complex carbs

Carbohydrates come in a few basic forms:

Simple carbohydrates are sugars made of one or two sugar units, such as glucose, fructose (fruit sugar), sucrose (table sugar) and lactose (milk sugar).
Complex carbohydrates are long chains of sugar units. Starch is the main digestible kind, and fiber is the main kind you can’t fully digest.

Here’s the twist: the simple-versus-complex label doesn’t tell the whole story. Whole fruit contains simple sugars but also fiber, water and vitamins, which makes it a great choice. White bread is mostly starch, technically a complex carb, but because the bran and germ have been stripped away, it digests quickly and offers little fiber. That’s why many nutrition experts focus more on whole versus refined than on simple versus complex.

Complex carbs at a glance

Category	Examples	Notes
Whole grains	Oats, brown rice, barley, quinoa, bulgur, farro, whole-wheat bread and pasta, corn, millet, buckwheat	Keep the bran, germ and endosperm, so their fiber and nutrients stay intact
Legumes	Lentils, black beans, chickpeas, kidney beans, split peas	Rich in both fiber and protein
Starchy vegetables	Potatoes, sweet potatoes, corn, peas, winter squash, plantains, cassava	Eat the skin where possible for extra fiber
Refined grains	White bread, white rice, many crackers and pastries	Faster to digest and lower in fiber; often enriched with some B vitamins and iron

Why carbohydrates matter

Carbohydrates are your body’s preferred fuel, especially for your brain and for muscles during hard effort. The National Academies set a Recommended Dietary Allowance of 130 grams of carbohydrate a day for adults, based on the brain’s typical glucose use, and suggest carbs supply about 45% to 65% of daily calories. Most people easily eat more than the minimum, so the real question is which carbohydrates you choose.

Complex carbs from whole foods offer:

Fiber, which supports digestion and fullness. See our full guide to dietary fiber.
B vitamins, iron, magnesium and potassium, especially in whole grains and beans.
Steadier blood sugar, because fiber and intact grains slow digestion. Our glycemic index explainer goes deeper.

How to spot a true whole grain

Packaging can be confusing. A few tips help:

Look for the word “whole” before the grain in the first ingredient, such as whole wheat, whole oats or whole-grain corn.
Don’t rely on color. Brown bread can get its shade from molasses or caramel coloring and still be made mostly from refined flour.
Know that “multigrain,” “seven-grain,” “wheat flour” and “made with whole grains” don’t guarantee a whole-grain product.
Check the fiber line on the Nutrition Facts label and compare similar products.

The Dietary Guidelines recommend making at least half of your grains whole grains.

Easy ways to eat more complex carbs

Start the day with oatmeal or a whole-grain cereal.
Use brown rice, quinoa, barley or farro as the base for bowls and salads.
Mix half white and half brown rice, or half regular and half whole-wheat pasta, while you ease in.
Add beans or lentils to soups, chili, tacos and salads.
Roast sweet potatoes, squash or potatoes with the skin on.
Keep whole-grain tortillas, pita or crackers on hand for quick meals.
Choose popcorn, which is a whole grain, as a crunchy snack.

A day built on whole carbohydrates

Breakfast: overnight oats with chia seeds and sliced banana
Lunch: lentil and vegetable soup with a whole-grain roll
Snack: an apple and a small handful of almonds
Dinner: a stir-fry of tofu or chicken with mixed vegetables over brown rice

What about sugar?

Not all simple carbs are a concern. The sugar naturally present in whole fruit and plain milk arrives with helpful nutrients. The type worth limiting is added sugar, which our guide to added sugar covers in detail.

The bottom line

Complex carbs are the starches and fibers found in whole grains, legumes and starchy vegetables. The most nutritious ones are whole and minimally refined, bringing fiber, vitamins and minerals along with steady energy. Look for “whole” on the ingredient list, add beans to your week, and enjoy fruit and starchy vegetables without worry.

Frequently asked questions

Are potatoes a complex carb?

Yes. Potatoes are a starchy vegetable, and starch is a complex carbohydrate. Eating them with the skin adds fiber, and baking, boiling or roasting them with a little oil keeps them a nutritious choice compared with deep-fried versions.

Is white rice a complex carb?

Technically yes, because it's mostly starch. But it's a refined grain, so it has less fiber than brown rice and digests faster. White rice can absolutely fit into a healthy diet, especially paired with vegetables, beans or other protein.

Are complex carbs good for weight loss?

Whole-food complex carbs like beans, whole grains and vegetables are filling thanks to their fiber, which can make it easier to feel satisfied on fewer calories. Portions still matter, but there's no need to cut carbohydrates out to lose weight.

Is fruit a simple or complex carb?

Fruit contains mostly simple sugars, but it also brings fiber, water, vitamins and minerals. That package makes whole fruit a healthy choice, quite different from sugar added to drinks and sweets.

Sources

This guide is general information, not medical advice. For a health condition, pregnancy or a history of disordered eating, please talk with a doctor or registered dietitian.