Do I Subtract Fiber from Carbohydrates?

| Nov 1, 1999

Q: In the past, the American Diabetes Association (ADA) recommended that when a serving of food has 5 or more grams of fiber, people should subtract that number from the total grams of carbohydrates, because fiber is not broken down into glucose.

I don't see this mentioned anymore, even in resources that incorporate high-fiber foods into diabetes diets. Now, more information discusses the glycemic index of high-fiber foods instead. Are people supposed to count and cover with insulin all of the carbohydrates in a serving of black beans, 23 grams, or subtract the 15 grams of fiber, and say it is 8 grams carbs?

Karen Lavine, RN, CDE
Albuquerque, New Mexico

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A: You are correct and the example is a good one. The ADA recommendations on adjusting carbohydrate calculation for high-fiber foods remain the same. Foods high in fiber are a healthy addition to a meal plan. Since fiber is not completely digested and absorbed, a high-fiber meal would not provide as much available carbohydrate as a low-fiber meal of similar total carbohydrate content.

A high-fiber food is one that contains 5 or more grams of dietary fiber per serving. When there are 5 or more grams of fiber per serving, subtract them from the total grams of carbohydrate to determine how much carbohydrate is available.

For example, a breakfast cereal containing 28 grams of total carbohydrate and 6 grams of dietary fiber can be counted as 22 grams [28 - 6 = 22] of available carbohydrate.

Anne Daly, MS, RD, CDE
Vice President, Health Care and Education
American Diabetes Association
Springfield, Illinois

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Posted by Anonymous on 1 March 2008

I have a disorder that makes me have to be on a low carb diet of 30g a day or less. My doctor told me to subtract fiber from the carbs cause the fiber helps keep the carbs from raising the blood sugar. Some carbs are not good at all on this type of diet like the ones that the 1st ingredient says "enriched flour." Don't think because it has little carbs that those are still good ones. Good Luck to all on a low-carb diet.

Posted by Anonymous on 16 January 2010

is the answer yes or no ..?!

in the uk. yes i subtract fibre, or no, the carb label is as-is


Posted by Anonymous on 4 March 2010

My question is: what if you eat a food that contains only 4 grams of fiber per serving, but you eat 2 servings (and therefore 8 grams of total fiber) - can you then subtract half of the total fiber from the carb amount?

Posted by Anonymous on 17 January 2011

If fibre is not digested, then why are the grams still counted for calories?

Posted by Anonymous on 11 November 2012

When it comes to soluble and insoluble fiber, I have heard it is only the soluble fiber that slows the absorption of glucose into the blood. In other words, it is only the soluble fiber that can be subtracted from the total grams of carbohydrates. Because many of the food labels do not decipher between the two, I have been told to focus only on the total carbohydrates. Is this true?

Posted by Anonymous on 19 June 2014

As an registered dietitian and certified diabetes educator I feel that it is much more straightforward to recommend counting total carb even if fiber is high. It can be confusing to remember the 5 gram rule for many and not everyone's blood glucose is affected the same way by fiber. The type of fiber can affect the rise in blood glucose and it is often not broken out on a label. Counting total carb is easier and may give people better control over blood glucose.

Posted by Anonymous on 2 November 2014

So if something is 4 carbs with 1 fiber u should subtract the 1 from the 4? Only do so when the carbs are 5 or more what happens if I subtract the 1 from the 4?

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