They boost your energy and help you burn fat, science now says. Learn how to fuel up the healthy way.
There's so much confusion about carbs these days. Popular eating plans like the keto diet and paleo diet claim that ditching them is the key to gaining muscle, losing weight, and revving energy. But active women and elite athletes are increasingly turning to plant-based diets, which are naturally higher in healthy carbs, to power their performance. (And, BTW, plant-based isn't necessarily the same as vegan.) So once and for all, what's the full story?
Despite the trend toward heavy proteins, your body must have carbs to function properly, experts say. (Like Bob Harper, who insists you can lose weight without giving them up.) Beyond bread, pasta, rice, and potatoes, carbs are also prevalent in fruit, green vegetables, legumes, and even milk. These foods are full of other healthy nutrients the body needs, including B vitamins, vitamin C, potassium, calcium, and fiber, so if you limit carbs, you're missing a lot.
Without carbs, your energy level and your workout performance also take a hit. That's because their main job is to stock us up with glucose, a type of sugar that's our primary source of fuel, says Cassandra Forsythe, Ph.D., R.D.N., an assistant professor of physical education and human performance at Central Connecticut State University. That glucose moves into the liver and muscles to create glycogen stores, which your system draws on whenever it needs strength and stamina. Your body also uses the glucose from carbs to burn fat for energy, says Michele Olson, Ph.D., a professor of sport science at Huntingdon College in Alabama.
Glucose powers the brain too. Women who ate a no-carb diet for one week performed worse on memory tests than those who followed a low-calorie diet, according to research from Tufts University. "If you cut off the supply of glucose, the brain can't operate as effectively, and learning and memory decline," says Holly A. Taylor, Ph.D., the study author.
Finally, glucose is key to keeping us happy and satiated. "It helps the brain absorb the amino acid tryptophan, which spurs the production of serotonin, a neurotransmitter that boosts the mood and suppresses the appetite," says Lisa Mosconi, Ph.D., the author of Brain Food.
Since carbs are necessary for energy and good health, the key is choosing healthy carbs and eating them at the right times to optimize their benefits. Here's how to get what you need.
How many carbs per day?
The amount of carbs you should eat each day depends on your size and activity level. For women who work out moderately most days, two grams of carbs per pound of body weight provides the perfect amount of fuel (a tablespoon of cooked rice has about two grams of carbs). But if you're regularly putting in more than an hour of intense, sustained effort, you may need more, Olson says. For every 30 extra minutes you work out, eat an additional gram of carbs per pound of weight, she suggests. (Here's everything you need to know about carb cycling.)
Healthy carbs are complex carbs.
Whole grains, legumes, and fruits and vegetables are far better choices than simple carbs (like white rice, white bread, and baked goods) because they are higher in fiber, which may help to keep your energy—and your weight—steady, lower your risk of heart disease, and promote better GI health, says Keri Gans, R.D.N., a nutritionist in New York City and author of The Small Change Diet. Aim for 25 grams of fiber per day, from foods like oats, beans, whole-grain bread and pasta, and produce. A good rule of thumb: 20 percent of a food's carbs should come from fiber, Forsythe says. That means a slice of bread with 15 grams of total carbs should contain three grams of fiber. (Also see: What You Need to Know About Resistant Starch)
Spread your carb intake throughout the day.
To keep your energy levels stable, consume small amounts of carbs at each meal and snack, and always pair them with protein. Combining the two nutrients helps you feel full and satisfied, keeps your metabolism humming, and helps your body build muscle, Forsythe says. "Eat one gram of protein for every two grams of carbs," she advises. Try an apple with peanut butter or whole-grain crackers with cheese. If you're doing a tough workout, eat a snack with 35 to 55 grams of carbs an hour or two beforehand so your body will have enough glycogen stores to keep you fueled. (This guide can help you decide which pre-workout snack is best for your workout.)