Accurately determine the carb content of foods to nail your health goals

Katherine Isacks, MPS, RDN, CDCES - Registered Dietitian and Certified Diabetes Care and Education Specialist (CDCES)

Knowing the carb content of the foods you eat is helpful whether you are working hard to manage blood sugar or body weight. Review these different ways to count carbs so you can stay on track and achieve results.

Why is it important to pay attention to the carb content of foods?

Carbs are found in a variety of foods commonly consumed. Counting carbs can help you reach your weight-loss goals and understand how food impacts blood sugar. If you have diabetes, this essential skill will help keep blood sugar in target range since carbohydrate directly affects your blood sugar level. In fact, not knowing the carb content of foods in a meal or snack can impair your ability to control your blood sugar effectively. If you have diabetes, lack of carb knowledge in what you eat increases the risk for very high blood sugar (> 200 mg/dL) and low blood sugar (< 70 mg/dL).

3 primary methods of determining carb content of foods

Counting total carbohydrates

The most common carb counting method is counting "total carbohydrate" grams listed on the Nutrition Facts panel. Total carbohydrates are the sum of starch (which is not required to be listed), fiber, sugar, and sugar alcohol. This method accounts for the total possible carbohydrate grams that a given food or beverage could provide, regardless of digestibility.

Tip: People make the common mistake of just counting sugar grams when reading food labels. Focusing only on sugar underestimates the total carbohydrate load of any food containing starch.

Net carbohydrates

Another method of carb counting is calculating "net carbs." The MyNetDiary app and other trackers explain the definition of "net carb" as the total amount of digestible carbohydrate in a food or meal. Here it is:

Net carbs = total carbohydrate grams - fiber grams - sugar alcohol grams

This method assumes little breakdown and absorption of fibers and sugar alcohols present in food and, therefore, should not be included in carb counts. In terms of breakdown and absorption, fibers (especially soluble) and sugar alcohols are a mixed bag, consequently affecting blood sugar. Therefore, the diabetes carb count method was created (See below).

Tip: If you have diabetes and use net carbs to dose your insulin, consider talking with your doctor or diabetes educator about using the diabetes carb count method.

Diabetes carb count

This carb counting method is considered most accurate for those who take insulin and require exact estimated grams of absorbed carbs. Diabetes self-management classes usually teach this method. However, it is still an estimate. If you use an insulin-to-carb ratio to dispense rapid-acting insulin at meals (or if you were recently diagnosed and educated), you most likely use this updated carb count formula:

Total carbohydrate grams - 1/2 fiber grams - 1/2 sugar alcohol grams

To illustrate this diabetes carb calculation using the above formula, check out figures from the Nutrition Facts label for a snack bar by Atkins and an example of how this formula is used.

The Advantage Caramel Peanut Butter Nougat bar contains the following:

Total carbs: 20 grams

Fiber: 11 grams

Sugar alcohols: 7 grams

20 grams of total carbohydrate -5.5g fiber = 14.5g - 3.5g of sugar alcohol = 11 grams of carb

Suppose fiber or sugar alcohol content is less than five grams per serving. In that case, the adjustment will make little difference in the carb count, so you can simply use "total carbohydrates" instead.

Logging what you eat and paying attention to the carb content of foods are critical to understanding how different food and lifestyle factors affect your blood sugar and weight.

The MyNetDiary free app allows you to track carbs, while Premium membership provides access to tracking carbs, "net carbs," and the American Diabetes Association carb count.

Happy tracking!