Ask a Dietitian: What Makes Carbs Good or Bad?

This is a great question because navigating carbs continues to be a source of confusion. It also shows that our mindset about carbs is shifting from asking, “Do carbs make me fat?” to a focus on carbohydrate quality.  

This is huge because it recognizes that all carbohydrate-rich foods aren’t fattening or unhealthy—in fact, some carbs may be helpful when it comes to losing weight—but it also recognizes that there are less healthy carbohydrates that can make it harder to lose weight or lead to weight gain when eaten in excess.  

Before I share the bad and good, it’s important to understand what carbs are and the two contexts in which the term “carbohydrates” gets used.

• Carbohydrates are a macronutrient that, along with fat and protein, contributes to the overall energy or calories in food. Foods contain different amounts of these three macronutrients (fat, carbohydrates, and protein), as well as fiber, vitamins, and minerals. These amounts are used to classify foods as good sources of protein, fat, or carbs.
• The term “carbohydrate” is also used to refer to a type of food. For example, bread, cereal, muffins, pasta, rice, and pancakes are often referred to as carbs. Since carbohydrates are the primary macronutrient, referring to them as carbs isn’t necessarily incorrect, but using the term like this can make it easy to overlook other foods that are also primarily composed of carbohydrates. These foods include fruits and their juices, starchy vegetables like corn and potatoes, some dairy products, chips and snack foods made with flour, and foods and drinks with added sugars, such as cookies, candy, donuts, and sodas.

Now, back to the question at hand: What’s a good carb and what’s a bad carb? I don’t love calling any food “bad,” since there can be a place for most foods (in smaller amounts) in a healthy diet. I like to categorize carbs into three buckets: not-so-great, better, and best. 

Not-So-Great Carbs

These are items like donuts, cookies, cake, French fries, chips, and many snack foods. They’re usually made with white flour, which is stripped of fiber and B vitamins in the refining process and may also contain added sugars or unhealthy saturated or trans fats. 

Sometimes referred to as empty-calorie foods—aka ones that deliver a decent dose of calories but little to no nutrients or disease-fighting compounds—these carb-rich foods don’t offer much benefit to the body. 

Not-so-great carbs can also make weight loss and sticking with a healthy eating plan challenging. Refined flours and sugars require less digestion, which causes blood sugar to spike after eating them and then dip two to four hours later, which tends to increase cravings and appetite. While you don’t have to avoid these carbs completely, these types of foods are ones to limit. Also, pay attention to their effects on your energy levels, cravings, and hunger.

Better Carbs

Broadly speaking, these are slightly less refined sources of carbohydrates that usually contain little to no added sugars or unhealthy fats. They deliver some nutritional value, but they’re still missing parts of the grain that could make the carb-rich food much healthier. 

Better carbs include refined grains like white rice or quick-cooking oatmeal and foods made with refined flours like most pastas, crackers, breads, and cereals. This category also includes those breads, cereal, and snack foods that are sometimes labeled “multigrain” or contain a small amount of whole grains. Better carbs can fit within a healthy eating plan, but don’t rely on them as your primary source of carbs. Consider them your second choice when you can’t find a “best” carb choice and watch portion size.

Best Carbs

The best carbs are ones found in whole foods like fruits, vegetables, legumes, and whole grains, such as brown rice, quinoa, oatmeal, and farro. They’re also the ones found in minimally processed whole foods like 100% whole-grain breads, cereals, and pizza crusts, as well as pastas and crackers made with whole-grain flours or legume- or nut-based ones (think: chickpea pasta or almond flour crackers) and very minimal or no added sugar or fat. 

Best carbs should serve as your primary source of daily carbohydrates because they have the highest amounts of fiber, which is key to a healthy gut and blood sugar regulation. Many “best” carbs are also packed with disease-fighting compounds known as phytochemicals that exert antioxidant or anti-inflammatory effects in the body. 

The Bottom Line

Yes, some carbs are healthier than others, but even the ones you might categorize as “bad” shouldn’t be banned. Be smart about your carbohydrate choices by focusing first on vegetables, fruits, legumes, and whole-grain foods. Doing this allows you to sprinkle in your favorite pasta and save room on occasion for those cookies and chips. 

Carolyn Williams, PhD, RD, is the author of the new cookbook, Meals That Heal: 100+ Everyday Anti-Inflammatory Recipes in 30 Minutes or Less, and a culinary nutrition expert known for her ability to simplify food and nutrition information. She received a 2017 James Beard Journalism Award, and her work is regularly featured in or on respective websites for Cooking Light, RealSimple, Parents, Health, EatingWell, Allrecipes, My Fitness Pal, eMeals, Rally Health, and the American Heart Association. You can follow her on Instagram @realfoodreallife_rd or on carolynwilliamsrd.com.