Learn why people are counting net carbs, how to calculate them and if it's something you should be doing.

Brierley Horton, M.S., R.D.
February 18, 2020
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There's more than one type of carb—and how our bodies handle them differs. (Just when you thought nutrition was straightforward…)

Here's a quick Carb 101. There are two main types of carbohydrates: simple and complex. Simple carbs are found in fruit, milk, and milk products, as well as the foods you're typically told to limit—desserts, soda, fruit juice, candy, and—well—all sugar. Your body digests them easily (aka they get to your blood stream fast and raise your blood sugar quickly). Complex carbs are whole grains, beans, legumes, rice, pasta, and starchy vegetables—they're the ones that your body has to put in a little more effort into digesting. And when it comes to how your body uses carbohydrates, it gets a little trickier. There's something called net carbs. Here we break down what those are, how to calculate them, the net carb values of foods, plus help you figure out if you need to be looking at net carbs in the first place.

Pictured recipe: Air-Fryer Sweet Potato Fries

What Are Net Carbs?

Net carbs are considered the carbohydrates that your body actually digests, though there is no formal (or government-regulated) definition. Typically, net carbs are the total carbohydrates in a food minus fiber and minus sugar alcohols. But some definitions suggest that you subtract 100 percent of the fiber (because it just passes through your body) and only half of the sugar alcohols because they're partially digestible.

How to Calculate Net Carbs

Here's the equation: Total Carbohydrates – Fiber – Sugar Alcohols = Net Carbs

Let's take a large banana, for example: 31 grams total carbs – 3.5 grams fiber = 27.5 grams net carbs.

Here's the net carb value for a few other common fruits and vegetables:

  • Sweet Potato (1 large): 39g net carbs
  • Watermelon (1 cup): 11g net carbs
  • Strawberries (1 cup whole): 8g net carbs
  • Spaghetti Squash (1 cup): 8g net carbs
  • Avocado (1 whole fruit): 4g net carbs
  • Broccoli (1 cup florets): 4g net carbs
  • Zucchini (1 cup): 3g net carbs
  • Cauliflower (1 cup florets): 3g net carbs

Who Counts Net Carbs?

"Mostly people subtract fiber and sugar alcohols from total carbohydrate to estimate the amount of carbohydrate that affects blood sugar," explains Jill Weisenberger, MS, RDN, CDE, CHWC, FAND, author of Prediabetes: A Complete Guide. But the people who track their blood sugar regularly—folks with diabetes—don't necessarily calculate net carbs. "According to the American Diabetes Association, it is not necessary to subtract dietary fiber or sugar alcohols from total carbohydrates when carbohydrate counting," says Virginia-based Weisenberger. "Most diabetes educators work one-on-one with people taking insulin to determine the need to subtract fiber and sugar alcohols to maintain target blood glucose levels."

So, who is actually counting net carbs? The low-carb dieters—Atkins, Keto, etc. Since the Keto diet is so low in carbohydrates, counting net carbs gives you more wiggle room in your day. That can be important, especially to allow for healthy foods like vegetables in your diet.

Should You Be Counting Net Carbs?

One "side effect" of counting net carbs—at least for some folks—is a greater awareness of how much fiber they're eating, and a drive to up their fiber count. In this instance, we're all for counting net carbs because most of us don't get enough fiber in our diets and there are some serious perks (besides just being regular!) to eating more fiber.

Beyond that, it's hard to see what, if any benefits, exist behind counting net carbs. Especially when you consider that most health organizations and health professionals don't recognize—or recommend—counting net carbs.

While that may be disappointing to hear if you're on a low-carb diet, there really isn't a need to count net carbs. If you are counting them, it may be a way to include more complex carbs in your diet—but otherwise we just recommend you choose more of those healthy foods to begin with.

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