First off, let’s get one thing straight: carbohydrates are not hellspawn determined to hide your six-pack, give you diabetes, and stop up your heart. That probably comes as a surprise to anyone who has tried a diet in the last decade—Paleo, gluten-free, Whole 30, Atkins, ketogenic, it doesn’t matter. After all, they all come with one simple directive: cut carbs and go medieval on any grain that attempts to make its way onto your plate.
And while some sources of carbohydrates have deservedly terrible reputations, saying all carbs are bad oversimplifies a pretty complex issue—and can compromise your health and fitness. See, calories are one of the three macronutrients (along with protein and fat) that your body needs in hefty amounts in order to grow, sport a healthy metabolism, and keep your body working as designed. Every gram of carbohydrates—whether it’s from sugars, starches, or fibers found in fruits, veggies, dairy, and grains—contains four calories. That’s the same as protein, and four less than fat, FYI.
But what carbs really have over their fellow macronutrients is their ability to keep your energy levels up, your brain humming along, and oxygen everywhere it needs to go. “Carbohydrates are the only nutrient that exists solely to fuel the body,” says Donald K. Layman, Ph.D., professor emeritus of food science and human nutrition at the University of Illinois. The two tissues that use the bulk of your body’s carbohydrates—both those floating through your bloodstream as glucose and stored in your liver and muscles as glycogen—are your brain and your muscles, the latter primarily during high-intensity and endurance exercise. Meanwhile, your entire central nervous system as well as your red blood cells run exclusively on carbs—burning through about 80 grams a day, he says. That’s why, when you eat less than 80 grams of carbs per day, your brain is eventually forced to break down fat to produce ketones, a poor man’s glucose that can keep your run brain running, albeit through a cloud of low-carb confusion.
It’s Simple: Complex Carbs Rock
While the Institute of Medicine has set the recommended dietary allowance of carbs at 130 grams per day (that equates to about 10 slices of bread), physically active people will likely need more, Layman says. But more important than the amount of carbs you eat is their sources, says Frank Sacks, M.D., professor of cardiovascular disease prevention and nutrition at the Harvard School of Public Health.
Whole carbohydrates found in vegetables, fruit, dairy, and whole grains like brown rice, quinoa, and whole wheat bread, are linked to a lower risk of obesity, Type 2 diabetes, and heart disease, according to Sacks. They have several things going for them. First off, their carbohydrates are complex, meaning that their chemical structure is long and branched.
“They are difficult for the body to break down, and that’s a good thing for your health. They slow digestion and the absorption of sugars into your bloodstream so that you don’t experience the spike in blood sugar and insulin that’s associated with fat storage and the development of chronic diseases like Type 2 diabetes and heart disease,” explains Gail Cresci, Ph.D., R.D., a gastroenterology and hepatology researcher with the Cleveland Clinic. Once they reach your intestines, the bacteria in your gut have a field day chowing down on the stuff. Your gut microbiota prefers complex carbohydrates over any other food source, and when it breaks them down, it releases compounds into your bloodstream that are linked with lower levels of inflammation and a stronger immune system, she says.
What’s more, one unique form of complex carbohydrate, fiber, is not broken down into sugars for energy. Fiber passes through your digestive system intact, regulating the body’s use of sugars to keep your blood sugar and hunger levels in check. Fiber helps you fill up quicker, and stay full longer so you don’t end up overeating or grabbing he unhealthiest foods imaginable when your blood sugar levels plummet and you get decidedly hangry. One 2015 Annals of Internal Medicine found that when people up their fiber intake, they end up losing just as much weight as they do when they go on full-fledged diets. People need at least 25 of fiber per day for good health, but most Americans get 10 to 15.
And, all carbs aside, foods that contain complex carbohydrates are also dense sources of vitamins, minerals, and, in the case of whole grains and dairy products, protein and fat—all of which translate into better health. (Even Paleolithic humans made flour from wild cereal grains, according to Sacks, so you can tell your Paleo friends to suck it.)
Why We’re Fatter Than Ever
Remember the Food Pyramid tacked on the cafeteria wall in your grade school? Well, they didn’t do anything for our collective waistlines. “For decades, American health policies were based on avoiding fat, which we now know isn’t all bad either. So without any direct research, policy makers structured the Food Pyramid around eating less fat and animal products, and more low-fat carbohydrates,” Layman says. “Look back, and that’s exactly what Americans did. They decreased milk, egg, and red meat intake, but increased refined grain consumption by 50 to 60 percent.”
Meanwhile, with more and more demands on their time and energy, Americans reached to more packaged foods, cooked less, and increasingly opted for shelf-stable (read: carb-rich) snacks over sit-down meals, per one 2013 Nutrition Journal study. They started every morning with a bowl of sugary cereal, kept their pantries stocked with white pasta, and drank soda during their 3pm slumps. The low-fat frenzy of the 90s didn’t help. When food manufacturers removed fat from cookies, ice cream, and chips, they replaced it with sugar in an effort to improve flavor, Cresci says.
The end result: the average American putting away almost three times the RDA of carbs (equaling about an extra 880 calories a day), most of them from refined carbohydrates and added sugars. It’s a recipe for winding up in Wall-E’s floaty chair. After all, for every benefit of whole carbs, refined ones come with pretty much the exact opposite effect. When you eat refined (aka processed) carbohydrates from sources like white bread and pasta, pastries, soda, and desserts, your blood sugar and insulin levels spike, you find yourself starving 30 minutes later, your gut microbiota spews out potentially health-wrecking compounds, and you set yourself up for metabolic dysfunction, elevated triglyceride levels, and chronic disease down the road.
It’s cutting these refined carbs that makes many people lose weight on low-carb diets, Cresci explains. Cut sugars, and you’ll cut calories—not to mention blood sugar swings, insulin spikes, and inflammatory compounds. Although it’s also worth mentioning that when you’re on a low-carb diet, your body quickly burns through its stores of muscle glycogen, or stored carbs. And for every molecule of muscle glycogen you burn, your body releases two molecules of H2O, she says. Translation: Cut carbs and a lot of the weight you lose, especially in the beginning, will actually be from water.
Oh yeah, and about fruit. While they are filled with carbs, especially simple carbs that have the potential to spike your blood potential, they also come with plenty of fiber to keep things under control. In fact, a 2013 BJM meta-analysis found that fiber from fruit can reduce your risk of cardiovascular disease. “Anyone who cuts down on fruit to reduce their sugar intake is making a big mistake,” Sacks says. OK, following the Banana Girl’s advice and eating 90 percent of your calories from carbs, almost entirely from fruit, would be overkill, but you get the picture.
Don’t Fear Gluten-Packed Grains
Unless you have Celiac disease or a gluten intolerance, there’s no reason to cut out gluten-containing whole gains like wheat, barley, and rye. All are great sources of iron and B vitamins, which are critical to keeping your energy levels up, Cresci says. What’s more, many G-free breads, pastas, and other baked goods contain more fat, salt, sugar, and calories than their conventional counterparts, and 2014 research published in the Journal of Medicinal Food suggests that people who follow a gluten-free diet are at a greater risk of obesity than are those who embrace wheat. After all, when food manufacturers take gluten—the protein responsible for making grain-products so fluffy, chewy, and altogether magnificent—out of their formulas, they have to add something to keep it from feeling and tasting like cardboard.
Fuel Your Workout, Boost Recovery
When you train above 70 percent of your VO2 max (the peak amount of oxygen your body can take in and use in a minute) most of your energy has to come from either stored carbs in your liver and muscles, called glycogen, or carbs floating through your bloodstream as glucose, Layman says. While, the fitter you are, the harder you’ll have to work to hit your 70 percent VO2 max, most people will reach theirs when performing any high-intensity total-body or compound workouts like sprinting, rowing, or circuits. If you’re too out of breath to chat, that’s good.
As long as you aren’t following a severely low-carb diet (ahem, Keto), your body should have enough carbs on board for completing power and strength workouts. But if you’re getting with high-intensity interval training (HIIT)—interspersing periods of all-out effort with moderate activity for recovery—or endurance exercise, you’ll need to consume about 40 to 60 grams of extra quick-acting carbs per hour during your workout, says Stuart Galloway, Ph.D., an exercise metabolism researcher at the University of Stirling in the UK. 2013 research published in Sports Medicine shows that carbs boost both endurance and HIIT performances. And better performances burn more calories—period. Whatever type of workout you prefer, you need to follow it up with a snack that has about a 4:1 ratio of carbs to protein, like chocolate milk, and apple and stick of string cheese, or pita bread and hummus. Yes, after your workout, you actually need more carbs than you do protein. According to research in the Journal of the International Society of Sports Nutrition, insulin, which your body releases when you eat carbs, helps the protein you eat build more muscle.
And while carbo-loading leading up to any race is a must, transitioning between high- and low-carb diets on a day-to-day basis isn’t shown to have any benefit from a sports-performance standpoint, Galloway says. And, in the average person, carb-cycling may actually hurt health. “Shifting back and forth between extremely low and high insulin levels can potentially cause low-grade inflammation,” says Cresci. “Plus, your body works really hard to maintain your blood glucose levels. If you burn through your carbs on your low-carb days, your body will find another way to get the glucose it needs, like by breaking down your muscles.”