Understanding Carbohydrates: What They Are and Why They Matter

Carbohydrates are one of the three main macronutrients—alongside protein and fat—that your body needs in significant amounts. Found in foods such as fruits, vegetables, legumes, grains, and dairy, carbohydrates include sugars, starches, and fiber. They are the body’s primary energy source and also support digestion, blood sugar regulation, and overall health.

Not all carbs are created equal. While whole food sources of carbohydrates—like beans, whole grains, and fruit—offer vital nutrients and health benefits, heavily refined carbs and added sugars can negatively impact your health.

Types of Carbohydrates

Carbohydrates are generally categorized into simple and complex types, depending on their chemical structure and how quickly they are digested.

Simple Carbohydrates

Simple carbs consist of one or two sugar molecules. These include:

• Monosaccharides: Glucose, fructose, galactose
• Disaccharides: Sucrose (table sugar), lactose (milk sugar), maltose

Simple carbohydrates are found naturally in some foods like fruits and dairy, but they’re also added to processed products like candy, sodas, and baked goods. These added sugars can cause spikes in blood sugar and insulin, increase appetite, and contribute to weight gain and chronic disease if consumed in excess.

Complex Carbohydrates

Complex carbs—also called polysaccharides—contain three or more linked sugar units. Unlike simple carbs, they digest more slowly and provide a steadier release of energy. Sources include:

• Starches: Found in potatoes, corn, whole grains
• Fiber: Present in beans, vegetables, fruits, and whole grains

Fiber is especially beneficial, as it supports digestion, reduces cholesterol levels, promotes fullness, and nourishes beneficial gut bacteria.

Health Benefits of Carbohydrates

Provides Energy for Your Body

Carbohydrates are converted into glucose, the fuel that powers your cells. Unused glucose is stored as glycogen in your liver and muscles and used when your body needs extra energy—like during exercise or fasting.

Each gram of carbohydrate provides 4 calories, and for most people, carbs are the largest source of daily energy.

Supports Digestive Health with Fiber

Many carbohydrate-rich foods are high in fiber, a plant-based compound that isn’t digested in the small intestine. Instead, fiber is fermented in the large intestine, producing short-chain fatty acids (SCFAs) like butyrate that strengthen the gut lining, reduce inflammation, and support immune function.

There are two main types:

• Soluble fiber: Dissolves in water and helps manage blood sugar and cholesterol
• Insoluble fiber: Adds bulk to stool and supports regular bowel movements

Fiber-rich diets have been linked with a lower risk of colon cancer, heart disease, and type 2 diabetes. Fiber also helps regulate appetite by stimulating satiety hormones like GLP-1 and PYY.

Despite these benefits, over 90% of women and 97% of men in the U.S. do not consume the recommended 28 grams of fiber per day.

Provides Essential Nutrients

Many carbohydrate-containing foods, such as fruits, vegetables, and legumes, also offer essential vitamins and minerals, including:

• B vitamins for energy metabolism
• Vitamin C for immune health and collagen production
• Potassium and magnesium for blood pressure and muscle function

How Much Carbohydrate Do You Need?

The recommended carbohydrate intake varies based on age, activity level, and health status. However, general guidelines suggest that 45% to 65% of your daily calories should come from carbohydrates.

This range may be adjusted:

• Higher-carb diets (e.g., plant-based diets) may benefit endurance athletes and people with high cholesterol.

• Lower-carb diets may help manage conditions like type 2 diabetes or fatty liver disease and can aid in weight loss.

Interestingly, a large study of over 15,000 adults found that those who consumed a moderate amount of carbohydrates (50–55% of total calories) lived the longest, suggesting a balanced intake may be optimal for most people.

Regardless of the quantity, the quality of the carbohydrates matters most.

Nutritious Carbohydrate Sources

Focus on whole, minimally processed sources of carbs that offer fiber and nutrients. Examples include:

Limit intake of refined carbs, such as:

• White bread and white rice

• Pastries and cookies made from refined flour

• Sugar-sweetened cereals and beverages

Potential Risks and Side Effects

When consumed in the right amounts and from high-quality sources, carbohydrates pose little risk. However, diets high in refined carbohydrates—especially added sugars—can:

• Spike blood sugar and insulin levels

• Increase triglycerides and LDL cholesterol

• Contribute to weight gain and fatty liver disease

• Raise the risk of heart disease and stroke

One large study found that women consuming 15% or more of daily calories from added sugars were 20% more likely to develop heart disease. Even just one sugar-sweetened drink daily was linked to an increased risk of stroke.

To lower health risks, the American Heart Association recommends limiting added sugar intake to no more than 6% of daily calories—about 6 teaspoons for women and 9 teaspoons for men.

A Quick Recap

Carbohydrates are essential nutrients that serve as the body’s main source of energy. Whole-food sources of carbs—like fruits, beans, vegetables, and whole grains—offer fiber, vitamins, and minerals that support digestion, weight management, heart health, and more.

While some individuals may benefit from low- or high-carb diets, most people thrive on a moderate carbohydrate intake focused on nutrient-dense, fiber-rich foods. To stay healthy, prioritize complex carbohydrates and limit refined carbs and added sugars.