Eating with Diabetes: Counting ''Net'' Carbs

Since low carbohydrate diets became popular, the phrase "net carbs" has become a fairly regular fixture on the labels of food products. But, if you are not familiar with the term you may be wondering what in the world it means!

There are three types of carbohydrates: starches, sugars and fiber. All three types of carbs are added up and listed as Total Carbohydrates on the Nutrition Facts Label of a food product.

The concept of net carbs is based on the fact that, although it is considered a carbohydrate, dietary fiber is not digested the same way the other two types of carbohydrates (starches and sugars) are. While starches and sugars are broken down into glucose (blood sugar), fiber isn't treated the same way. The fiber you eat passes through the body undigested and helps add bulk to your stool (among other benefits). The indigestibility of fiber is where the idea of "net carbs" comes in. In fact, sometimes, net carbs are sometimes referred to as "digestible carbs.''

In recent years, food manufacturers have started including net carbs in addition to total carbs when labeling products. Many foods proudly display net carbs on their labels to entice both low-carb diet fans and people with diabetes.

While the concept of net carbs can be utilized in diabetes meal planning, read labels with a discerning eye. At present there are no mandated rules for calculating or labeling net carbs on food packages. The FDA does not regulate or oversee the use of these terms, and exactly what is listed as "net carbs" can vary dramatically from product to product. Some products calculate net carbs as total carbohydrates minus dietary fiber, other labels reflect net carbs as total carbohydrates minus dietary fiber minus sugar alcohols, and still others calculate net carbs as total carbohydrates, minus dietary fiber minus sugar alcohols minus grams of protein.

Many packaged foods that are marketed as high in fiber low in carbs actually add extra fiber, such as inulin, polydextrose and maltodextrin, to food products to lower the net carb serving. Most nutrition experts agree that these "stealth fibers " do not have the same health benefits and may not have the same benign affect on blood sugar levels as foods that contain naturally occurring fiber. As you can see, the whole issue of "net carbs" can get tricky very fast. And for people with diabetes, for whom carbohydrate counting and blood glucose control is a serious issue, referring to net carbs on a food label can have serious consequences.

However, counting net carbs can work for people with diabetes who use a meal-planning technique known as carbohydrate counting to help balance their blood sugar levels—when done correctly.

Here's how a person with diabetes can count net carbs safely and effectively:
  • The food in question must contain at least 5 grams of dietary fiber in the serving size you are planning to eat.
  • Read the Nutrition Facts label or look up the nutrition facts of the food to find both the total carbohydrates and total fiber for the serving size you plan to eat.
  • Subtract HALF the total grams of fiber from the total grams of carbohydrates to calculate the net carbs in your food serving.
  • Always perform this calculation yourself and do not rely on "net carb" totals listed on any food label.
Take the following example (see food label, left):

This product has 5 grams of dietary fiber, which means you can subtract half that amount (2.5 grams) from the total carbohydrate (23 grams) to calculate net carbs, which equals 20.5 grams per serving.

The whole point of counting net carbs versus total carbs is to allow someone to eat more of a carbohydrate-containing food without adversely affecting their blood sugar levels. If you find the issue of net carbs confusing, don't worry about it. There is no reason to use this technique if counting total carbohydrates works well for you. Both options can work as long as you are doing them correctly and reading "net carb" labels with a discerning eye.

For more specific information or help, talk to your health care provider. The American Diabetes Association's National Call Center also offers live advice from 8:30 a.m. to 8 p.m. EST, Monday through Friday at 1-800-DIABETES or 1-800-342-2383.
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Member Comments

Thank You..............
. Report
very informative for sure. My husband has diabetes Report
Great article Report
good info Report
interesting article. No wonder fiber is under is listed as a carb Report
Thanks! Report
WOW! That took me by surprise. I thought carbs-fiber=net carbs. I had no idea that you use only half the fiber. Report
Thank you for trying to make more sense out of "net carb counting" as it can become more confusing if a person doesn't read the label but relies on just what the manufacturers put Report
Like this Report
It is so easy to do once you do it one time. Thank you for the simple chart to instruct! Report
Interesting, but confusing. I had no idea there were so many ways to figure net carbs, which convinces me that it has just become a marketing tool for food manufactures, good reason that I also have become a fan of reading the ingredients section, as well as the nutrition. Just look for something with simple ingredients I understand, and not a lot of junk. Fiber from whole fruits and vegetables is the best! Report
Interesting but too complicated for me. Report
Thank-you Report
Great information. Thanks. Report
CD10676776
Excellent need-to-know information, thanks! Report


 

About The Author

Amy L. Poetker
Amy L. Poetker
Amy Poetker is a licensed and registered dietitian and certified diabetes educator with a master's degree in dietetics. Amy, who has spent most of her career working in diabetes education, is dedicated to the treatment of that disease and the prevention of related complications. See all of Amy's articles.