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Eating with Diabetes: Counting ''Net'' Carbs

What Are Net Carbs? How Do They Affect Blood Sugar?

-- By Amy Poetker, Registered Dietitian and Certified Diabetes Educator
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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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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.

Member Comments

  • For the last 6 months I have concentrated my efforts on watching carbs. Basically, not going over 35-45 carbs..per meal (usually 30 or so) I am a type 2 and its imperative for me to reduce my weight and get in shape....so far i have taken off approx 35-40#. I am excited to look and feel better. - 6/2/2014 7:59:01 AM
  • SISTERJJ
    Steve07171, I think that what you said about carbs may help me. I have type 2 my doctor says I've got to lose the weight .But it's so hard I'm 50 years old,I walk 3 miles every day Monday - Friday Saturday @ Sunday I rest still not enough .Maybecouting gcarbs will help me. I hope - 2/8/2014 9:56:33 PM
  • JSMITH61
    I like to keep my net carbs to 30- 35 per day. I recently started to use carbquik as a substitute for bread, when you look at the carbs its kind of scary, but then look at the fiber. Only two net carbs per biscuit. - 1/14/2014 7:25:54 PM
  • AEMERO54
    I like this web page it help know thing I did know about my dives how to plan my maels - 9/8/2013 5:34:58 PM
  • This was a great article. My father had adult onset diabetes so this is a concern for me. I feel like I can make better choices now with this simple formula. Thank you. - 5/23/2013 8:12:44 PM
  • I hope the author will expand on views of the health benefits of the various types of fiber that are noted on nutrition labels and made available as dietary supplements. - 3/22/2013 9:31:03 AM
  • Well, I'm surprised I actually agreed with most of what this article had to say!

    I'm a type 2 diabetic, and I don't subtract fiber from my carb counts, but I would think it would be fine to do for non-diabetics who just want to eat low carb.

    Atkins and such says subtract 100% of the fiber. So if something has 10 total carbs, but 6 grams of fiber, you'd count 4. I'd go ahead and count 10, because it's kind of life and death for me. Non diabetics? Not so much, so they can go ahead and subtract it all.

    And of course, everyone absorbs fiber differently. Some people - diabetics included - really don't digest much of the fiber in foods. Some, however, do. I've had my blood sugar spiked by flax seed before!

    In the end, we should all do what works for us, which is what this article says, which is why I agreed with it. - 3/22/2013 12:22:19 AM
  • thanks after all i have read that is the correct answer but if you read the article on carb counting above it says half is subtracted which will throw some people - 2/1/2013 8:45:14 PM
  • Not to repeat other posts, but net carbs are minus ALL the fiber! - 1/31/2013 3:03:07 PM
  • after reading all of this article i have one BIG question. every thing i read says subtract ALL fiber but this article says only half of the fiber is used so QUESTION IS WHAT HAPPENS TO THE OTHER HALF OF THE FIBER????????????
    ? does it turn into sugar in the blood or what???? - 1/29/2013 12:28:05 PM
  • As I help my dh on a low carb diet, I often refer to diabetes recipes and suggestions. The nutrition tracker does not always reflect the net carbs accurately - esp when I have a recipe or nut info from another source to compare with it. I know this can be reflected in any recipe we use on SPARK, but it doesn´t come out right on the tracker frequently . - 11/1/2012 10:10:49 AM
  • Each individual reacts to the different types of sugars in various ways. Fewer carbs as determined by the treatment team is always best. However, in my experience, after time, solely counting carbs is not what works best for me. A certain balance of different types, along with proteins, healthy fats, and the all important exercise is what helped me to lose weight, and rid myself of the need for medications. - 7/19/2012 9:22:08 PM
  • Every place I read or attended lectures on Diabetes everyone stresses that Carbs cause your blood sugar to increase – known fact. This is very true SO if you want to control your blood sugar the simple solution is to CUT the carbs out. My wife is diabetic and has kept her total daily carb intake to less than 20 grams each day and in 26 months has lost 110 pounds. IT WORKS for weight control but what is even better is she is taking 30% of the insulin that she was talking before the new eating plan. Keep the carbs down and the blood sugar and weight are down. - 7/19/2012 2:55:58 PM
  • Seems much more practical to eat simple, whole foods that aren't so over-processed - and look at all the totals -- protein, fat, and carbohydrate -- when planning a day's meals.
    - 7/19/2012 10:45:10 AM
  • STEWLAD
    I have been to several diabetes classes and had been taught that as long as there are at least 5 grams of fiber the entire amount could be deducted. If there are less than 5 grams nothing could be could be subtracted. I wonder if this is new information. It has been several years since my classes but this would definitely make a difference. - 7/19/2012 10:00:35 AM