Everything You Need To Know about Carbohydrates

Carbohydrates are one of three macronutrients, which are nutrients your body needs in large amounts. Carbohydrates refer to sugars, starches, and fibers. Carbohydrates give you energy and support digestive health, blood sugar control, and other necessary processes within your body.

Carbohydrates in foods like starchy vegetables, beans, grains, dairy products, and fruit support health in several ways. Certain types of carbohydrates are better for health than others. Eating more complex carbs, including vegetables, beans, and fruit, may improve health outcomes. A diet high in refined (ultra-processed) carbohydrates and added sugar can harm health and increase the risk of obesity, fatty liver disease, and many other health conditions.

Types of Carbohydrates

Carbohydrates are categorized as simple or complex based on the number of units of sugars they contain. 

Simple Carbohydrates 

Simple carbohydrates are made of one or two sugar units. The simplest carbohydrates are monosaccharides (simple sugars), made from just one sugar unit. Monosaccharides include glucose, fructose, and galactose. All carbohydrates break down into monosaccharides in the body, which are easily absorbed and immediately used for energy.

Disaccharides are carbohydrates made of two monosaccharides bonded together. Disaccharides include sucrose, maltose, and lactose.

Simple carbohydrates naturally occur in foods like yogurt and fruit. Simple carbohydrates are also added to foods and drinks to enhance their sweetness. Sweeteners like corn syrup and sucrose (table sugar) are added to candy, baked goods, ice cream, and beverages to make them more palatable. 

Consuming too many foods and drinks high in simple sugars can harm health by increasing blood sugar and insulin levels and triggering weight gain. This is because simple sugars cause a rapid increase in blood sugar, and foods high in simple sugars are much less filling than complex carbohydrates due to lower fiber and protein content. Diets high in simple carbohydrates are linked with an increased risk of health conditions like obesity, type 2 diabetes, and heart disease.

Complex Carbohydrates 

Complex carbohydrates, or polysaccharides, contain three or more sugar units (monosaccharides) bonded together. While the body rapidly absorbs simple carbohydrates, complex carbohydrates are challenging to break down and take longer to digest, leading to a more gradual increase in blood sugar.

Fiber is a polysaccharide in foods like beans, grains, fruits, and vegetables. Dietary fibers are indigestible carbohydrates that are necessary for digestive health. Fiber feeds beneficial gut bacteria, prevents constipation, and promotes feelings of fullness after eating.

The seeds, roots, and tubers of plants contain starches, another polysaccharide. Starch is the primary dietary source of glucose, the major energy source for your body's cells. Starches are concentrated in starchy vegetables like corn and potatoes.

Potential Benefits of Carbohydrates 

Carbohydrates are the body's preferred energy source. Complex carbohydrates also provide fiber, a nutrient linked with several health benefits, including lowering disease risk and protecting against obesity. 

Provides Fiber and Other Nutrients

Fiber is an indigestible carbohydrate, meaning it resists digestion in the small intestine and is instead broken down or fermented by bacteria in your large intestine. There are two main categories of fiber: soluble and insoluble.

Soluble fibers dissolve in water. Bacteria ferment soluble fibers in your large intestine, releasing compounds called short-chain fatty acids (SCFAs). SCFAs (e.g., butyrate and propionate) act as a fuel source for intestinal cells, regulate inflammation in the intestinal tract, and strengthen the gut lining. SCFAs also support overall health by improving immune function and regulating immune response.

Fiber also helps digestion by drawing water into your stool (poop), which keeps it soft and easy to pass. It also regulates cholesterol levels by reducing cholesterol absorption and promoting cholesterol excretion through the stool.

Unlike soluble fiber, insoluble fiber passes through your digestive system intact. Insoluble fiber adds bulk to your stool and speeds its movement through your intestines. Foods high in insoluble fiber, like wheat bran and whole grains, are a good choice for people with constipation.

Dietary patterns high in fiber are linked with several health benefits, including a lower risk of several common diseases, such as type 2 diabetes, heart disease, and colon cancer.

In addition to reducing disease risk, fiber slows digestion and stimulates the release of satiety hormones, like peptide YY (PYY) and glucagon-like peptide-1 (GLP-1). These hormones tell your brain you've had enough to eat, reducing calorie intake. High-fiber diets are effective for aiding weight loss and decreasing the risk of obesity.

Most people in the United States fall short of the recommended 28 grams of daily fiber. Research findings suggest that more than 90% of women and 97% of men fail to meet the recommended daily fiber intake. Consuming fiber-rich carbohydrates, such as beans, fruits, and vegetables, can help you meet your daily fiber needs.

Some carbohydrate-rich foods contain beneficial levels of other nutrients, such as vitamins and minerals. Fruits, vegetables, and legumes provide B vitamins, vitamin C, and minerals like potassium and magnesium, all of which play critical roles in health.

Gives Your Body Energy

The primary role of carbohydrates is to provide your body with energy. Your body turns carbs into glucose, the main energy source for your cells. There are four calories per gram of carbohydrates, making it the macronutrient that is the largest source of calories for most people. Calories indicate how much energy a food or drink will provide the body.

When you consume carbohydrates, your body breaks them down into glucose (sugar), which it can immediately use for energy. Your body stores glucose that you don't need immediately in the muscles, liver, and other areas as glycogen. It releases glycogen for energy when glucose is in short supply, such as during periods of calorie restriction or high-intensity exercise.

How Much Do You Need?

Though everyone has different carbohydrate needs, there are general recommendations for macronutrient intake. Acceptable macronutrient distribution ranges (AMDRs) are the percentage of total calorie (energy) intake from a macronutrient associated with a reduced risk of chronic disease. The AMDRs are as follows:

• Carbohydrates: 45-65% of total calorie intake
• Fats: 20-35%
• Protein: 10-35%

Carbohydrates make up the highest percentage of most people's energy needs.

Though these recommendations suit most people's dietary needs, some populations may require higher carbohydrate intake, while others may benefit from a low-carbohydrate diet. Studies show that low-carbohydrate diets that are higher in fat and protein may help people with certain health conditions, such as fatty liver disease and type 2 diabetes. Low-carbohydrate diets have also been effective for weight loss.

Higher-carbohydrate diets (e.g., plant-based diets) may be more appropriate for people with high cholesterol. Athletes, such as long-distance runners, are another population that may thrive on high-carb diets.

Though high- and low-carbohydrate diets have certain health benefits, a moderate-carbohydrate diet may be the best choice for most people. A study of data on over 15,000 people found that diets of high and low percentages of carbohydrates were associated with increased mortality rates. The study found that people with the longest lifespans consumed 50–55% of total calories in carbohydrates—considered moderate in the U.S.

The researchers also found that diets high in carbohydrate-rich foods like vegetables, legumes, and whole grains were linked with lower mortality rates, suggesting that the type of carbohydrate consumed significantly affects overall health and longevity.

While moderate-carbohydrate diets may be appropriate for most people, it's best to personalize your carbohydrate intake based on your overall energy needs and health goals. You can also speak to your healthcare provider for further guidance.

Good Sources of Carbohydrates 

There are many nutritious carbohydrate sources to choose from, including:

• Navy beans: 53.4 grams (g) of carbohydrates per cup
• Brown rice: 51.7 g per cup
• Black beans: 40.8 g per cup
• Quinoa: 39.4 g per cup
• Oats: 27 g per one-half cup
• Bananas: 27 g per medium-sized (about 7 inches long or 118 g) banana
  
• Sweet potato: 20.7 g per 3.5-ounce (oz) serving of baked sweet potato
  

Fruits, grains, starchy vegetables, and legumes provide carbohydrates and other essential nutrients such as fiber, vitamins, and minerals. Experts recommend limiting refined carbohydrates found in foods such as white bread, white rice, baked goods made with white flour, and certain cereals.

Potential Risks and Side Effects

Carbohydrates consumed in appropriate amounts are not associated with many health risks. You can reduce risks and support overall health by choosing more nutritious kinds of carbohydrates and staying within your daily calorie needs. Consuming more energy from carbohydrates than your body needs will result in weight gain.

Refined carbohydrates low in fiber and protein are more likely to cause weight gain. Studies show that while diets high in complex carbohydrates like whole grains, fruit, beans, and non-starchy vegetables are associated with weight loss, increased refined grains and added sugar intake can cause weight gain. A diet high in added sugar is linked to other health risks, such as high blood sugar levels, fatty liver disease, and heart disease.

A review of data on over 109,000 women found that those who consumed 15% or more of their total daily energy intake as added sugar were 20% more likely to develop heart disease (including coronary heart disease) compared to women who consumed less sugar. The study also found that consuming one or more servings of sugar-sweetened beverages per day was associated with an increased risk of stroke.

To support overall health and lower your disease risk, health organizations recommend choosing complex sources of carbohydrates, such as whole grains, beans, fruits, and vegetables, while limiting refined carbohydrates and added sugar. 

The American Heart Association recommends limiting added sugars to no more than 6% of calories per day—about 6 teaspoons of added sugar for women and 9 teaspoons for men.

A Quick Review

Carbohydrates are a macronutrient that makes up the highest percentage of most people's calorie intake. Carbohydrates are an important energy source for your body. Some types of carbohydrates are high in fiber, supporting digestive health and protecting against conditions like obesity and heart disease.

Everyone has different nutrient needs, and some populations benefit from lower- or higher-carbohydrate diets. A moderate-carbohydrate diet tends to be the best choice for most people.