What Are the Two Types of Complex Carbs and Their Health Benefits?

November 4, 2025 •

3 min read

While simple carbohydrates consist of one or two sugar molecules, complex carbohydrates are made of long, intricate chains of sugar molecules that take longer to break down. This article explains what are the two types of complex carbs, starch and fiber, and why they are fundamental to a healthy, balanced diet.

Quick Summary

The two types of complex carbohydrates are starches, which the body digests for energy, and fiber, which passes undigested to aid digestive health. Both are crucial for providing sustained energy and supporting overall wellness.

Key Points

Two Types: The two types of complex carbs are starch and fiber, both consisting of long chains of sugar molecules.
Starch for Energy: Starch is broken down into glucose more slowly than simple sugars, providing a sustained release of energy and preventing energy crashes.
Fiber for Digestion: Fiber is an indigestible complex carb that promotes regular bowel movements, aids in cholesterol control, and feeds beneficial gut bacteria.
Diverse Sources: Healthy sources of both complex carbs include whole grains, legumes, starchy vegetables, fruits, and nuts.
Health Benefits: A diet rich in complex carbs supports stable blood sugar levels, weight management, heart health, and overall digestive wellness.
Quality Over Quantity: Choosing whole-food sources of complex carbs, such as whole grains over refined grains, is crucial for maximizing nutritional benefits.

What Are the Two Types of Complex Carbs?

Complex carbohydrates, or polysaccharides, are vital macronutrients that are composed of long chains of sugar molecules. Unlike simple carbohydrates, which are broken down quickly for immediate energy, complex carbs provide a sustained release of glucose into the bloodstream, offering a more stable and lasting source of fuel. The two primary types of complex carbohydrates found in our food are starch and fiber. While both are complex in structure, the body processes them in distinctly different ways, leading to unique health benefits.

Starch: The Body's Sustained Energy Source

Starch is a storage polysaccharide produced by plants to hold glucose for energy. When we consume starchy foods, our digestive system breaks down these long chains of glucose molecules into simple sugars that are then absorbed and used by our cells for fuel. This process is slower than with simple sugars, preventing the rapid blood sugar spikes and subsequent energy crashes often associated with high-sugar foods.

Sources of healthy starches:

Whole Grains: Brown rice, oats, quinoa, whole wheat pasta, and whole-grain bread.
Legumes: Lentils, chickpeas, and beans.
Starchy Vegetables: Potatoes, sweet potatoes, and corn.

Fiber: The Indigestible Digestive Aid

Fiber is another type of complex carbohydrate, but it is unique because the human body cannot fully digest or absorb it. Instead, fiber passes through the digestive system relatively intact. This indigestible quality is what makes it so beneficial for promoting digestive health, regulating blood sugar, and supporting a healthy gut microbiome.

There are two main types of dietary fiber:

Soluble Fiber: This type of fiber dissolves in water to form a gel-like substance in the digestive tract.
- Benefits: Helps lower blood cholesterol and glucose levels, and contributes to a feeling of fullness.
- Sources: Oats, apples, beans, peas, and citrus fruits.
Insoluble Fiber: This type of fiber does not dissolve in water.
- Benefits: Adds bulk to stool, which promotes bowel regularity and helps prevent constipation.
- Sources: Whole-wheat flour, nuts, beans, and vegetables like green beans and cauliflower.

Comparison Table: Starch vs. Fiber


Feature	Starch	Fiber
Digestibility	Digestible; broken down into glucose.	Indigestible; passes through the body largely intact.
Energy	Primary source of sustained energy.	Not a direct energy source, but aids in digestion.
Blood Sugar	Gradual, slow rise in blood sugar.	Helps to regulate blood sugar levels.
Satiety	Contributes to feeling full and satisfied.	Promotes a feeling of fullness, aiding weight management.
Gut Health	Can include resistant starch that feeds gut bacteria.	Acts as a prebiotic, feeding beneficial gut bacteria.
Food Sources	Whole grains, starchy vegetables, legumes.	Whole grains, fruits, vegetables, legumes, nuts, seeds.

The Role of Complex Carbs in a Balanced Diet

Incorporating both starch and fiber into your daily meals offers significant health advantages beyond just energy provision. For example, a diet rich in complex carbohydrates supports heart health and can reduce the risk of type 2 diabetes by stabilizing blood sugar levels and improving insulin sensitivity. By choosing whole-grain options over refined grains, you retain the valuable fiber, vitamins, and minerals that are often stripped away during processing.

For practical integration, consider these simple swaps: choose brown rice instead of white, add lentils to your soups, or snack on whole fruits and nuts rather than simple sugars. These dietary changes can help ensure you're getting a steady supply of energy while reaping the numerous benefits of dietary fiber. The Centers for Disease Control and Prevention (CDC) provides numerous resources on smart carbohydrate choices and healthy eating.

Conclusion

In summary, the two types of complex carbs are starches and fiber. Both are essential for a healthy diet, but they serve different roles. Starches are the body's primary source of sustained energy, while fiber promotes digestive health and helps regulate blood sugar and cholesterol. By understanding the distinction and prioritizing whole-food sources of both, you can make informed choices to support your overall health and well-being. Focusing on a variety of whole grains, legumes, and fiber-rich fruits and vegetables will ensure you are fueling your body with the nutrients it needs to thrive.

Frequently Asked Questions

Complex carbs are long, complex chains of sugar molecules that take longer to digest, providing sustained energy. Simple carbs are shorter chains of sugar molecules that are digested quickly, leading to rapid blood sugar spikes.

Excellent sources include whole grains (brown rice, quinoa), legumes (beans, lentils), starchy vegetables (sweet potatoes, peas), and fruits.

Yes, complex carbs, especially those high in fiber, can aid in weight management. They promote a feeling of fullness for longer periods, which can reduce overall calorie intake.

Yes, resistant starch is a type of starch that resists digestion in the small intestine, acting similarly to fiber. It is fermented in the large intestine and supports gut health.

No, starches are not inherently bad. Healthy starches from whole foods provide essential energy, vitamins, and minerals. However, refined starches found in processed foods lack many beneficial nutrients.

Experts recommend that adults consume around 25 to 30 grams of fiber per day. Most people consume only about half of this amount.

While it is possible to include some complex carbs, many low-carb diets significantly restrict them. It is important to discuss dietary needs with a healthcare provider to ensure a balanced approach and avoid nutrient deficiencies.