You’ve definitely heard the term “carbs” before, but what are carbohydrates, really—and what’s the best way to incorporate them into your diet?
Both of those questions seem relatively straightforward, but for many people they can become pretty loaded. That’s because like many things in the nutrition field, there has been a lot of controversy (and misconceptions) around carbs.
Carbohydrates have gone through quite a journey in the public eye. In 1992 the U.S. Department of Agriculture’s Food Pyramid debuted with bread, cereal, rice, and pasta at the bottom, suggesting that these carb-rich foods should be the most prevalent items in your daily diet.
But just over a decade later, opinions shifted: The Atkins Diet and other low-carb eating plans surged in popularity, making health-conscious consumers believe that carbs were something that should be limited, or even avoided. In fact, when Regina George asked her fellow Mean Girls whether butter was a carb, she exemplified the common belief of the early aughts that carbs were to be off-limits.
Today you may still be feeling a bit perplexed about where things stand with carbs, especially when we add specifics to the mix, such as “refined” and “complex” as carb descriptors to consider. The short answer? Experts recommend eating plenty of them (especially nutrient-dense sources like whole grains, fruits, vegetables, beans, peas, and lentils). As for why you should eat them, and how to incorporate them into your diet? Read on to find out more.
What are carbohydrates, really?
Carbohydrates are one of three macronutrients (along with fat and protein) that our bodies use for energy—each gram of carbs provides four calories for your body’s fuel. All carbs are sugar molecules, and they come in two main varieties: simple carbs and complex carbs.
Simple carbs include the sugars with the most basic molecular structures: monosaccharides and disaccharides. Some examples include fructose (found in fruit), lactose (found in milk), and sucrose (found in table sugar).
Complex carbs, which are three or more simple sugars bonded together, have more complex molecular structures. They include starches (found in wheat and potatoes) and fibers (found in vegetables, seeds, and brown rice). When whole grains are processed and stripped of their outer shell, or bran, they are known as refined grains. These refined carbs, like white rice and white flour, tend to act more like simple carbs in your body (more on that below).
“Any plant-based food is carbohydrate,” Bridget Murphy, M.S., RDN, CDE, CDN, a clinical dietitian at New York University Langone Medical Center, tells SELF. “So all of our fruits, vegetables, beans, legumes, even our peanut butter—they all have carbohydrates in them.”
What do carbohydrates do in your body when you eat them?
Your body breaks carbs down into the simple sugar glucose, your body’s main energy source that you either burn during physical activity or store in muscles or fat for later use. Compared with protein and fat, carbs break down more easily into glucose, says Murphy. This allows carbs to be used quickly for energy, like when you’re exercising.
As you put the carbs in your mouth, you start digesting them. Amylase, an enzyme that breaks down starch, is released in your saliva to begin the process, Murphy says. The process continues as food travels down your esophagus and into your stomach and intestines, where the carbs break down further into simpler components. (The process is easier and quicker for simple carbs than complex carbs, says Murphy.) Then your body absorbs the simple sugars, which make their way to your bloodstream. This glucose in your blood, commonly known as blood sugar, then travels throughout your body through circulation to supply energy to your tissues.
All carbohydrates provide energy when they’re digested, but they affect your body in different ways. For instance, because you digest simple carbs faster than complex carbs, they can contribute to quick spikes in your blood sugar, says Murphy. In some cases that’s an advantage—say, if you’re exercising long and hard and you need easy fuel fast. But if you consistently take in lots of simple carbs (not related to exercise), that can lead to chronic levels of higher blood sugar, which can be hard for our bodies to move out of the bloodstream, says Murphy. Blood sugar is essential, but when it is elevated consistently for prolonged periods of time, it can raise your risk of developing type 2 diabetes. Plus, if you eat simple carbs by themselves (say, not with fat, protein, or complex carbs), you tend to get hungrier quicker and not stay satisfied for as long.
Complex carbs like fiber, though, can be a more filling choice because your body can’t really digest them—most of it passes through your digestive system. Plus, fiber slows down the movement of food through your system, improving satiety. When you eat carbs with fiber, “your blood sugar won’t spike as quickly because it’s not releasing and dumping all at once,” says Murphy. “It’s gradually releasing out to the bloodstream.” There are two types of fiber: insoluble fibers, which get their name because they don’t dissolve in water, help food move through your system faster. That’s why they are famous for keeping your bowel movements regular. Soluble fibers dissolve in water and turn into gels as you digest them, and some types have been linked to a reduction in heart disease risk. They can also make your poop softer and easier to pass.
Some starches, like resistant starch found in bananas, potatoes, grains, and legumes, have also been shown to increase satiety and lead to smaller blood sugar increases than simple sugars.
How many carbohydrates should you eat a day?
The amount of carbs you should eat per day varies based on a bunch of factors like your age, sex, and activity level. But as a general rule of thumb, according to the Dietary Guidelines for Americans, women ages 31 to 50 should eat 45% to 65% of their daily calories from carbohydrates, or about 130 grams per day. That total should include at least 25 grams of fiber and less than 10% of daily calories from added sugars.
Aim for a diverse mix of fruits, vegetables, and whole grains so you take in plenty of fiber and a variety of important nutrients, Bahram H. Arjmandi, Ph.D., R.D., a professor in the department of nutrition, food, and exercise sciences at Florida State University, tells SELF. “We should diversify our food sources rather than eating the same thing,” he says.
More than 90% of people don’t eat enough dietary fiber, so odds are that you need to ramp it up too. It’s okay—and, actually, a good idea—to start slowly. “If you have not been eating a lot of fiber, I wouldn’t just jump right to 30 grams of fiber per day,” says Murphy. “You would want to gradually increase your fiber intake because if you take too much at once, it can cause a lot of bloating and other G.I. problems.” Consider adding in foods like blackberries (about eight grams of fiber per cup), cooked bulgur (four grams per half cup), cooked lentils (eight grams per half cup), or avocado (five grams per half cup).
As you assess your diet, also consider your workout habits. If you aren’t taking in enough carbs to fuel your exercise—remember, they’re your bodies’ preferred macronutrient for fuel during it—your exercise performance can falter, and it can feel much harder, as SELF recently reported. Carbs help your muscles work more efficiently and adapt better to training. The American College of Sports Medicine recommends eating between three to five grams of carbs per kilogram of body weight per day for light exercise (low intensity or duration), five to seven grams for moderate exercise (about an hour per session), and 6 to 10 grams for high-level exercise (greater than one hour of moderate to high effort). That means a 150-pound woman who exercises about 30 minutes a day should take in about 204 grams to 340 grams per day.
One thing to consider about that total amount of carbs for people who exercise frequently is timing: You probably will want to use some of your total for a carb-rich preworkout snack—usually 15 to 30 grams before your workout, depending on duration and intensity, says Murphy. Keep it the size of a small snack if you’ll be eating it 30 to 60 minutes before your session, and make it low in fiber and fat, which can cause G.I. distress while exercising, as SELF reported.
Then, if your workout is long or hard—say, over an hour—you may also want to take in 30 to 60 grams of carbs per hour during it, which can help you fuel your muscles and maintain steady blood sugar levels to optimize performance, according to the ACSM. You’ll also want to refuel with carbs afterward, too: Shoot for 1 to 1.5 grams per kilogram of bodyweight within 30 minutes of finishing to refill your glycogen stores, according to the National Academy of Sports Medicine.
So what kinds of carbs should you eat?
Okay, so that takes care of how many carbs to eat, but what about which kinds to eat? Chances are pretty high you’ve heard people refer to those complex carbs as “good carbs,” while the simple kind are given that “bad carb” label. But that’s way too simplistic—while complex carbs are different than simple carbs, they aren’t better than them. And each has a place in your diet.
“There is no such thing as a bad carb and a good carb,” Dr. Arjmandi says. Besides, there are no “good” foods or “bad” foods in general, anyway. Plus, our bodies have evolved to break down complex carbs into simpler components, including mono- and disaccharides, he says. In other words, even when you eat complex carbs, simple carbs end up in your body.
Still, in some cases, those differences in the types of carbs are something you should be aware of, especially if you have health conditions like type 2 diabetes or heart disease, or are at risk for those conditions. Over time big spikes in blood sugar can increase your risk of type 2 diabetes by reducing the function of beta cells, which produce insulin to help you process blood sugar.
In those cases, focusing on complex carbs may be especially helpful. Complex carbs play important roles in digestion, pushing bile salts through your system and fermenting in your guts to produce beneficial short-chain fatty acids, says Dr. Arjmandi. These short-chain fatty acids can promote blood sugar control, reduce inflammation, and more. A 2019 meta-analysis published in the American Journal of Clinical Nutrition concluded that when people substituted starches for equally caloric sugars, their low-density lipoprotein (LDL cholesterol, or the kind that can clog blood vessels when your body has too much) and fasting blood sugar levels fell.
Simple carbs—especially added sugars—on the other hand, have been linked to cardiovascular issues. For example, a 2021 meta-analysis published in Advances in Nutrition found that every daily serving of sugar-sweetened beverages was associated with an 8% increased risk of cardiovascular disease and an 8% increased risk of dying from cardiovascular disease. (It’s important to note limitations for studies like these, though. For instance, the researchers caution that reverse causation may be in play here, because some people might have existing health problems that can affect the relationships between these beverages and cardiovascular risk. It’s also possible that people who limit their consumption of sugar-sweetened beverages may also take part in other health-promoting behaviors.)
Overall, though, balance is key: There’s a time and place for everything, says Murphy. Sugary beverages, for instance, can be beneficial when used to restore dangerously low blood sugar levels in a person with type 1 diabetes. And as we mentioned before, simple carbs can also be super helpful for quick bursts of energy during exercise, or for quick refueling of your glycogen stores afterward. They can also just…be delicious and something you enjoy eating.
And food and culture are closely linked: If you grew up loving pasta or white rice or something else made with simple carbs, you might feel pressured to give them up for a more “complex” version. Instead, enjoy your favorite kind of carb, and just look to the rest of your diet as an opportunity to incorporate more nutrient-dense foods, like vegetables, suggests Murphy.
After all, balance and perspective are critical. “Having a healthy relationship with food is actually of the utmost importance as well,” says Murphy, “because if you’re constantly stressing about counting everything that you’re putting in your mouth, or only eating ‘good foods’ versus avoiding all the ‘bad foods,’ that amount of stress can actually have a more detrimental impact to your overall health than just having, you know, the piece of chocolate.”