Good vs. Bad Carbs: What Should You Eat?
When you’re focused on losing or maintaining weight, you get plenty of advice about carbs.
For instance, some carbs — like beans and legumes, fruits, whole-grain products and vegetables — contain vitamins, minerals and fiber that help fuel your body. And they’re less likely to cause spikes in your blood sugar, which can give you energy for a longer period of time.
But should you avoid carbs at all costs or just certain ones?
Dietitian Julia Zumpano, RD, explains the types of carbs and reveals the facts behind common carbohydrate myths.
Types of carbs
Carbs are a type of macronutrient that’s found in certain foods and drinks. Fiber, sugar and starch are considered carbs.
Carbs can be either simplex carbs or complex carbs. A couple factors determine whether food is considered a simplex or complex carb: its chemical structure and how quickly it gets digested into your body.
These types of carbs are digested easily, which can cause your blood sugar to spike. Simple sugars can be found in refined sugars (think white sugar) and added sugars (think a can of soda).
But sugar that naturally occurs in fruit and milk also has the added benefit of vitamins, minerals and fiber. Just be careful how much you consume, sticking to the daily recommended amounts of each.
When it comes to complex carbs, they digest more slowly into your bloodstream than simple carbs. This releases a steady stream of sugar that can help you feel fuller longer and provide energy.
But you need to watch what kind of complex carbs you eat. Look for unrefined whole grains that are rich in fiber and contain other nutrients like vitamin B.
Do you need carbs in your diet?
Yes. You can benefit from eating the right types and amount of carbs. Carbs can:
- Provide energy.
- Protect against disease.
- Control weight.
“Carbohydrates are our body’s main source of energy,” says Zumpano. “For most people, carbs are an essential macronutrient that provides the energy to get through a busy day.”
Carb myths to no longer buy into
Carbs can be a tricky subject. It’s hard to know what information to believe. Here, we break down four myths.
Myth 1: Carbs make you gain weight
“People often say that carbs are fattening,” says Zumpano. “But complex carbohydrates, like whole grains, are not fattening foods.”
This myth may spring from carbs’ effect on insulin. Eating carbohydrates raises your blood glucose (your blood sugar) and prompts your body to release insulin. This redirects your glucose to cells.
“But it’s the type and quantity of the carbs you eat — not carbohydrates themselves — that cause weight gain,” she notes. “Many carbs contain excess calories and sugar.”
Examples include desserts, white bread, rice and pasta, and snack foods like chips, crackers and pretzels. These refined carbs are stripped of the outside grain, which contains fiber and some protein, making glucose (sugar) levels spike quickly.
Carbs that contain fiber (like brown rice) or protein (like legumes) raise blood glucose more slowly, require less insulin and keep you full longer. But even complex carbs like whole grains, beans and fresh fruit should be eaten in moderation.
“For weight loss, a basic rule of thumb is to limit your carb intake to about 1 cup per meal (about the size of a coffee mug or woman’s fist),” says Zumpano.
Keep your carbohydrate intake to around 40% to 45% of your total calories. Healthy fats should make up 30% to 35% of your total calories, and lean proteins should make up the other 20% to 30%.
Myth 2: Only white foods contain carbs
“There seems to be lots of confusion about which foods even contain carbohydrates,” says Zumpano. “People often think only rice, bread, pasta, potatoes, sweets and sugary drinks are carbohydrates.”
Think beyond “white foods” to get a more complete list of high-carb foods, which also includes:
- Sweet potatoes.
- Winter squash.
- Grains, including millet, kamut, barley and bulgur.
- Dried beans.
- Brown and wild rice.
- Yogurt and milk.
“High-fiber carbs (like legumes, whole grains, starchy veggies and fruits) and high-protein carbs (like legumes, yogurt and milk) provide more nutrients than low-fiber carbs (like refined grains, sweets and sugary drinks),” Zumpano says.
Myth 3: All white foods should be avoided
“It’s true that white foods like processed grains and sweets are higher on the glycemic index, quickly raise blood sugar and cause inflammation,” notes Zumpano.
But other carb-rich foods — considered “white” due to the color of their inside layer — can be essential to good health.
“They contain plenty of phytonutrients, have antioxidant activity and support immunity,” she says. “For example, potatoes have a particularly bad reputation, but are great sources of potassium, fiber and vitamin C.”
But stick to the proper portion size: half a medium potato. (Medium potatoes weigh about 1/4 pound on the produce scale at your grocery store.)
Meanwhile, enjoy these other nutrient-rich white foods:
- Nuts and seeds.
- Onions and garlic.
Myth 4: Fruit is bad because it’s high in carbs
“People often say that fruit has too much sugar in it,” says Zumpano. “The truth is that fruit is dense in nutrients. Along with a natural form of sugar called fructose, fruit provides fiber, vitamins, minerals and phytonutrients.”
But many fruits today are far larger than the recommended portions, she cautions. That can make your daily calories and total carbs add up fast.
“One serving of hand fruit (apple, orange, peach, pear or plum) is the size of a tennis ball,” she says. “A 4-inch banana is one serving; so are 17 small grapes.”
Zumpano recommends fresh or frozen fruit (without added sugar) over fruit juice, too. “Fruit juice is more concentrated in fructose but lacks fiber,” she says. (Love fruit juice? Limit your portion to 4 ounces.)
The bottom line? Don’t write off carbs — they play an important role in a healthy, balanced diet.
“Pick carbs that are bursting with fiber and/or protein, vitamins and minerals, and neglect those devoid of nutrients,” advises Zumpano.