What Other Carbs Are There Besides Fiber and Sugar?

December 18, 2025 •

4 min read

According to the American Diabetes Association, all carbohydrates, including fiber, starches, and sugars, are essential food nutrients. While most people are familiar with simple sugars and indigestible fiber, a vast and often misunderstood world of other carbohydrates exists that plays a critical role in our health and energy levels.

Quick Summary

Beyond common fiber and simple sugars, other carbohydrates like starches, oligosaccharides, and glycogen are vital for energy storage, gut health, and more. Their structure and digestion rate determine their health impact and whether they provide slow-release energy or feed beneficial gut bacteria.

Key Points

Starches provide sustained energy: As complex carbohydrates, starches take longer to digest, releasing glucose into the bloodstream more gradually for lasting fuel.
Oligosaccharides are gut-health prebiotics: These short-chain carbohydrates are fermented by beneficial bacteria in the large intestine, supporting the microbiome and digestive wellness.
Resistant starch acts like fiber: This unique starch type bypasses digestion in the small intestine, feeding good gut bacteria and helping to regulate blood sugar and increase feelings of fullness.
Glycogen is the body's stored fuel: This is the body's internal storage form of glucose, primarily located in the liver and muscles, used for quick energy when needed.
Carbohydrate quality matters: Choosing complex carbs like whole grains and legumes over refined grains and simple sugars is important for maximizing nutrient intake and promoting stable energy levels.
Cooling foods can create resistant starch: The process of cooking and then cooling certain starchy foods, like rice and potatoes, can increase their resistant starch content.

The Three Main Categories of Carbohydrates

Most people know about sugars (simple carbs) and fiber (complex carbs), but the third major category of carbohydrates is starch. Together, starches and fiber are considered complex carbohydrates, which are made of many sugar molecules bonded together in long, complex chains. These complex structures are why they take longer to digest than simple sugars and offer a more gradual release of energy.

Starch: The Complex Powerhouse

Starch is a polysaccharide, a complex carbohydrate made up of a large number of glucose molecules linked together. Plants use starch as their primary way to store energy, which is why starchy foods are so prevalent in our diet. When we eat starch, our body breaks it down into individual glucose molecules, which are then used for energy. This process is slower than digesting simple sugar, resulting in a more stable release of glucose into the bloodstream.

Common sources of starch include:

Grains: Rice, wheat, oats, and barley
Legumes: Lentils, peas, and beans
Starchy Vegetables: Potatoes, corn, and sweet potatoes

Oligosaccharides: The Forgotten Gut-Helpers

Oligosaccharides are carbohydrates composed of a small number of monosaccharide (sugar) units, typically between 3 and 10. While they are less known, they play a critical role in gut health. Humans lack the enzymes to fully digest many oligosaccharides, so they travel to the large intestine where they act as a prebiotic, feeding the beneficial bacteria in our gut microbiome. This bacterial fermentation produces beneficial compounds called short-chain fatty acids (SCFAs), which support digestive health and immunity.

Sources of oligosaccharides include:

Legumes (chickpeas, lentils, kidney beans)
Onions, garlic, and leeks
Asparagus
Certain nuts like cashews and pistachios

Glycogen: The Body's Emergency Fuel

Glycogen is a polysaccharide that our body uses to store glucose for later use. When we consume carbohydrates, and our body doesn't need the glucose immediately, it is converted into glycogen and stored primarily in the liver and muscles. When blood sugar levels drop, or we need a quick burst of energy, our body can convert this stored glycogen back into glucose. Glycogen is not typically consumed directly in food but is a crucial internal carbohydrate for regulating energy.

Resistant Starch: A Unique Starch Type

Resistant starch is a type of starch that, as the name suggests, resists digestion in the small intestine. It functions much like dietary fiber, fermenting in the large intestine and feeding beneficial gut bacteria. It can improve glycemic response, support gut health, and contribute to a feeling of fullness. Resistant starch can occur naturally or be created by processing.

There are several types of resistant starch, including:

Type 1 (RS1): Physically inaccessible starch found in whole grains and seeds.
Type 2 (RS2): Starch that is resistant due to its structure, found in raw potatoes and unripe bananas.
Type 3 (RS3): Retrograded starch formed when starchy foods like rice or potatoes are cooked and then cooled.
Type 4 (RS4): Chemically modified starch often used in processed foods.

Comparison of Carbohydrate Types (Excluding Sugar and Fiber)


Feature	Starch	Oligosaccharides	Resistant Starch	Glycogen
Structure	Long, digestible chains of glucose.	Short chains (3-10) of sugar units.	Varies by type; some are long chains, some are encapsulated.	Highly branched, long chain of glucose.
Digestion	Slowly broken down into glucose in the small intestine.	Resists digestion in the small intestine, fermented in large intestine.	Resists digestion in small intestine, fermented in large intestine.	Broken down into glucose as needed for energy.
Primary Role	Provides sustained energy.	Acts as a prebiotic, feeding gut bacteria.	Supports gut health and provides satiety.	Energy storage for the body.
Sources	Grains, legumes, potatoes.	Legumes, garlic, onions, chicory root.	Unripe bananas, cooled potatoes, legumes.	Stored internally in muscles and liver.
Example	Brown rice	Lentils	Cooled white rice	Stored fuel in your body

Conclusion: A Broader View of Carbohydrates

Beyond the familiar classifications of fiber and sugar, the carbohydrate family is a diverse group that includes starches, oligosaccharides, glycogen, and resistant starches. Understanding these additional types is crucial for a complete picture of how carbohydrates fuel our bodies and support overall health. From the sustained energy provided by starches in whole grains to the gut-nourishing prebiotics in oligosaccharides and the internal energy reserves of glycogen, these carbohydrates all play distinct and vital roles. The key takeaway is that not all carbs are created equal; choosing a variety of complex, unprocessed carbohydrate sources, such as whole grains, legumes, and certain vegetables, provides a richer nutrient profile and more stable energy than relying on refined, high-sugar options. A balanced diet rich in these different carbohydrate types is essential for optimal health and wellness. For further reading on the physiology of these macronutrients, an authoritative resource can be found here: Physiology, Carbohydrates.

Frequently Asked Questions

Starch is a complex carbohydrate made of long, linked chains of glucose molecules, while sugar is a simple carbohydrate with one or two sugar units. Starch is digested slowly for sustained energy, whereas simple sugars are digested quickly, causing rapid blood sugar spikes.

Yes, many healthy and minimally processed foods are excellent sources of starch, including whole grains, legumes, and starchy vegetables like potatoes and corn. These also provide fiber, vitamins, and minerals.

Oligosaccharides are short-chain carbohydrates that are not fully digested in the small intestine but instead ferment in the large intestine. This process feeds beneficial gut bacteria, making them important prebiotics that support digestive health.

You can increase resistant starch by eating unripe bananas, legumes like beans and lentils, and cooked and cooled starchy foods such as rice and potatoes. Whole grains also contain Type 1 resistant starch.

Glycogen is stored primarily in the liver and muscle cells. The liver releases glucose from glycogen into the bloodstream to maintain blood sugar levels, while muscles use their stored glycogen to fuel activity.

Refined grains, such as white bread and pasta, have had their bran and germ removed, which strips away much of their fiber and nutrients. They primarily contain the starchy endosperm, which digests quickly and acts more like simple sugar in the body.

While resistant starch is often classified as a type of fiber because it resists digestion and is fermented in the large intestine, it is technically a form of starch. Many foods rich in fiber, like whole grains and legumes, also contain resistant starch.