Net Carbs
| Author: Judy Kohn, RN, BSN, CDE |
| Last Updated: Friday, March 17, 2006 |
Q: "I have had diabetes for 37 years and I do count my carbs. The new NET CARB craze has an effect on diabetic food exchanges. The formula says: Take total carbs (in grams), minus fiber, minus sugar alcohol = NET CARBS. I took a Carb Solution bar that says NET CARBS 3G. However, the bar breakdown is: Fat: 13g, Total Carbs: 15g, Fiber 1g, Sugars 1g, Protein 21g. If you subtract the fiber & sugars, you get 13g, not 3g. Why is this formula not working?? Also, does this formula work on all foods or only on these protein bars? Either way, the numbers didn't add up! This NET CARB formula may make a big difference in what I am able to eat each day. Can you explain how this formula is actually supposed to work? Why do some of the carbs not count (where do they go?) and why don’t the numbers add up on the above bar?"
A: You are not alone in your concern about this. I received so many questions on this topic that I asked assistance from Hope Warshaw, MMSc, RD, CDE, and noted author of Eat Out Eat Right (Surrey Books), Diabetes Meal Planning Made Easy1, Guide to Healthy Restaurant Eating*, Complete Guide to Carb Counting*, The Diabetes Food and Nutrition Bible* . She explained the issues and also included information from the 2nd edition of The Complete Guide to Carb Counting.
- How to read a label: The American Diabetes Association explains how to read a food label but note that they don’t provide the details for how to subtract sugar alcohols. Please read the information in the related questions, about how to subtract fiber and sugar alcohols.
- No FDA approved nutrition claims: Hope stated: “Net carb/effective carb are not terms that are defined by FDA’s food labeling regulations. These terms didn’t exist before the current low carb craze, as they have been created by the food industry to help sell their “low carb” foods. You’ll note from food labels that these terms are used outside of the Nutrition Facts panel. They essentially constitute advertising. In using these terms, food manufacturers are attempting to describe the fact that certain carbohydrates have either minimal or no impact on blood glucose (such as sugar alcohols or fiber). They are indicating that you can subtract the grams of sugar alcohols and fiber in a food because they are not digested or absorbed. This information is not in accordance with FDA food labeling regulations.”
- Conflicting information regarding sugar alcohols:
- Glycerol and glycerin (which are the same substance) are counted as sugar alcohol: The January, 2004 Journal of the American Dietetic Association explained that FDA nutrition labeling regulations require that when glycerin is used as a food ingredient, it must be included in the grams of total carbohydrate per serving. Also, when the label of a food containing glycerin has a statement regarding sugars, the glycerin content per serving must be declared as sugar alcohol.
- Hope elaborated: “The food manufacturers encourage you to count only the “net carbs” obtained by subtracting all the fiber and sugar alcohol grams. However, this isn’t true according to what is known about sugar alcohols. Sugar alcohols vary from 0.2 to 3.0 calories per grams. When more than one sugar alcohol is used in a food, it’s impossible to know how much of each is used and therefore impossible to know the actual calories per grams.”
- No mention of calories: "As part of this new calculation, manufacturers provide a statement to indicate that only the net carbs in the product have an impact on blood glucose. They do not make a statement about calories."
- Confusion and possible safety concern: Hope concluded: "Thus, the people for whom these new terms are a concern are people with diabetes, especially those who use insulin. Clearly for people who do advanced carb counting and take rapid-acting insulin to cover carbs using the "net carb" information vs. the guidelines provided above, this could cause them to underestimate their insulin need. This could lead to a higher blood glucose level several hours later, without an understandable explanation. This is both confusing and a safety concern. Until further notice it makes most sense to continue to count fiber and polyols (sugar alcohols) as noted above."
Diabetes guidelines conflict with the unapproved labeling claims on these products: To summarize what Hope stated, the diabetes guidelines provide specific advice (such as only subtracting the fiber if there are 5 or more grams present, as well as only subtracting half of the sugar alcohols, depending on the amount of sugar alcohol present in the particular food). However, many of these popular “low carb” bars are subtracting all the fiber and sugar alcohols (this includes glycerin, as explained above) in that product, which is why your math may conflict with the “net carb number” claimed on a product package.
The Bottom Line:
So how do you make sense out of all of this?
- Remember that individual effects can always vary, and the only way to determine your particular effects would be to test before and 2-hours after ingesting these products.
- Be sure to work closely with your diabetes team to determine how to safely incorporate these products into your meal plan.
1Published by American Diabetes Association
Related Questions
Effective Carbs for Fiber and Sugar Alcohols
Q:
"I am wondering what the term "effective carbs" means. I have read
that in addition to subtracting fiber grams, one may also reduce the total carb
count by the grams of sugar alcohols, to reach an "eff..."
Subtracting Fiber Grams from the Carb Grams
Q:
"I've just started getting the "hang" of carb counting, then I read
something on “Effective Carbs” that has thrown a monkey wrench in the mix. Does
subtracting the fiber content from a food really less..."
Related Links
Food and Drug Administration (FDA) Diabetes Information
http://www.fda.gov
American Diabetes Association (ADA)
http://www.diabetes.org
Books on healthy eating and carbohydrate counting: Books by Hope
http://www.hopewarshaw.com/books/index.htm
Important Notice: The responses provided by the team of Diabetes Educators are based on their personal experiences and expertise as practicing diabetes healthcare professionals, and are not to be considered diabetes management advice from Abbott Laboratories. Remember that information provided by the team of Diabetes Educators is for general background purposes and is not intended as a substitute for medical diagnosis or treatment by a trained professional. You should always consult your physician about any healthcare questions you may have, especially before trying a new medication, diet, fitness program, or approach to healthcare issues.
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