What are the two carbs called? Understanding Simple and Complex Carbohydrates

January 4, 2026 •

4 min read

Carbohydrates, a vital source of energy for the body, are primarily known by two main categories: simple and complex. These two types differ fundamentally in their chemical structure and how quickly the body digests them, impacting everything from energy levels to long-term health.

Quick Summary

This article details the primary classification of carbohydrates into simple and complex varieties based on their molecular structure. It explains the function and health implications of monosaccharides and disaccharides versus polysaccharides like starch and fiber.

Key Points

Simple vs. Complex: Carbohydrates are mainly classified into two types: simple and complex, based on their molecular structure and digestion speed.
Single and Double Sugars: Simple carbs are short-chain molecules, including monosaccharides (like glucose) and disaccharides (like sucrose and lactose).
Starches and Fiber: Complex carbs are long-chain polysaccharides, including starch, which is digestible, and fiber, which is not.
Energy Release: Simple carbs provide quick energy spikes, while complex carbs offer slow, sustained energy release.
Nutrient Density: Complex carbs from whole foods are typically more nutrient-dense and beneficial for long-term health compared to refined simple carbs.
Health Impacts: Overconsumption of refined simple sugars is linked to health risks, while complex carbs support stable blood sugar and digestive health.

The Two Main Categories of Carbohydrates

When most people ask, "What are the two carbs called?" the answer refers to the broad nutritional division of simple and complex carbohydrates. However, the scientific classification is more granular, dividing carbs into monosaccharides, disaccharides, oligosaccharides, and polysaccharides based on the number of sugar units. Simple carbohydrates encompass monosaccharides (single sugars) and disaccharides (double sugars), while complex carbohydrates consist of longer-chain polysaccharides like starch and fiber. The primary distinction lies in how quickly these different structures are broken down and absorbed by the body for energy.

Simple Carbohydrates: Fast Fuel

Simple carbohydrates, often referred to as sugars, are composed of one or two sugar molecules. Because of their simple structure, they are digested and absorbed very quickly, leading to a rapid spike in blood sugar followed by a crash.

Monosaccharides: The Single Sugars

Monosaccharides are the most basic form of carbohydrate and cannot be broken down further. They include:

Glucose: The primary energy source for the body, circulating in the bloodstream as 'blood sugar'. It is found in fruits, vegetables, and honey.
Fructose: The sugar found in fruits, fruit juice, and honey. It is the sweetest of all the monosaccharides.
Galactose: A sugar primarily found as part of the disaccharide lactose in milk.

Disaccharides: The Double Sugars

Disaccharides are formed when two monosaccharides bond together. Common examples include:

Sucrose: Commonly known as table sugar, it is made of one glucose and one fructose molecule.
Lactose: Found in milk and dairy products, it is composed of glucose and galactose.
Maltose: A sugar produced during the breakdown of starch, consisting of two glucose units.

Complex Carbohydrates: Slow and Steady Energy

Complex carbohydrates, or polysaccharides, are made of long, intricate chains of sugar molecules. This complex structure means they take much longer for the body to break down, resulting in a more gradual and sustained release of energy. They are a far more stable source of energy than simple carbohydrates.

Starches: The Storage Carb

Starch is a complex carbohydrate found in plants, used as their energy storage. When we eat starchy foods, our bodies break them down into glucose for energy. Good sources of starch include:

Potatoes and sweet potatoes
Legumes (beans, peas, lentils)
Whole grains (oats, barley, quinoa)
Brown rice and whole-wheat pasta

Fiber: The Indigestible Carb

Fiber is a type of complex carbohydrate that the body cannot digest. While it doesn't provide energy, it is crucial for digestive health and overall wellness. There are two main types of fiber:

Soluble Fiber: Dissolves in water and helps lower blood cholesterol and glucose levels. Found in foods like oats, apples, and beans.
Insoluble Fiber: Passes through the digestive system largely intact, adding bulk to stool and promoting regular bowel movements. Found in whole grains, seeds, and vegetables.

Health Implications and Making Smart Choices

Understanding the difference between simple and complex carbs is vital for managing your health. While simple carbs offer a quick energy boost, excessive consumption, especially of refined sugars, can lead to weight gain and increase the risk of conditions like type 2 diabetes. Complex carbs, particularly those from whole foods, provide sustained energy and often come packaged with beneficial nutrients and fiber.

Best Practices for Healthy Carb Consumption

To optimize your health, prioritize complex, nutrient-dense carbohydrate sources. A healthy plate approach, recommended by the USDA, suggests filling half your plate with fruits and vegetables and one-quarter with whole grains. This ensures you get steady energy along with essential vitamins, minerals, and fiber. Limit intake of refined and added sugars found in candy, sodas, and white bread. For more detailed guidelines on healthier eating, consult resources like the American Heart Association.

Comparison of Simple vs. Complex Carbohydrates


Feature	Simple Carbohydrates (Sugars)	Complex Carbohydrates (Starches, Fiber)
Chemical Structure	One or two sugar molecules (monosaccharides or disaccharides).	Long, complex chains of sugar molecules (polysaccharides).
Digestion Speed	Rapidly digested and absorbed.	Slowly digested and absorbed.
Energy Release	Provides a quick burst of energy, followed by a potential crash.	Provides sustained, long-lasting energy.
Effect on Blood Sugar	Causes rapid spikes and drops.	Promotes a more gradual and stable rise.
Fiber & Nutrients	Often lack fiber, vitamins, and minerals, especially if refined.	Typically high in fiber, vitamins, and minerals.
Food Examples	Honey, fruit juice, table sugar, milk.	Whole grains, vegetables, beans, legumes.

Conclusion

To answer the question, "what are the two carbs called?", the primary distinction is between simple and complex carbohydrates. The key difference lies in their molecular complexity and the subsequent impact on your body's energy and blood sugar levels. By prioritizing nutrient-rich complex carbohydrates found in whole grains, vegetables, and fruits, you can fuel your body with sustained energy, improve digestive health, and reduce the risk of chronic disease. While simple carbohydrates have a place in a balanced diet, it is best to choose those found naturally in whole foods and to limit refined and added sugars. Making informed decisions about your carbohydrate intake is a crucial step towards better overall health. For further reading, consult the American Heart Association at https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/nutrition-basics/carbohydrates.

Frequently Asked Questions

Scientifically, the two main types of carbohydrates are simple and complex. Simple carbs consist of one or two sugar molecules (monosaccharides and disaccharides), while complex carbs contain long chains of sugar molecules (polysaccharides).

Complex carbohydrates are better for sustained energy. They are digested slowly, providing a gradual and steady release of glucose into the bloodstream, which helps maintain stable energy levels.

No, not all simple carbohydrates are unhealthy. Simple sugars found naturally in whole fruits and milk come packaged with beneficial nutrients like vitamins, minerals, and fiber. It is the excessive intake of refined and added sugars that poses health risks.

Both starch and fiber are complex carbohydrates. The key difference is that the human body can digest starch for energy, while it cannot digest fiber. Fiber passes through the system and aids in digestive health, while starch is broken down into glucose.

Simple carbohydrates are made of short sugar chains that are quickly broken down into glucose during digestion. This rapid conversion causes a sharp increase in blood sugar levels, prompting the pancreas to release a large amount of insulin.

Foods rich in complex carbohydrates include whole grains (like brown rice and oats), legumes (beans, lentils), and starchy vegetables (sweet potatoes, peas).

Complex carbs, particularly those with high fiber content, help with weight management by promoting a feeling of fullness for a longer period. This satiety reduces the likelihood of overeating and excessive snacking.