What’s the Difference between Carbs, Total Carbs, and Net Carbs?
I was visiting my friend Tony and his wife when he showed me his new friend: a box of pasta that was going to revolutionize his Italian dinner. Enthusiastically, he said that this new cereal would have a minor effect on his blood sugar because it had very little carbohydrate and it tasted identical to his favorite brand.
His wife Betty served some of a plate and handed it to me. I tasted it and it was delicious. Betty handed the box of pasta and I looked at the amount of carbohydrates. It said 28 grams. I turned the box around and there it was, front and center, the magic words 5 Net Carbs.
What are Net Carbs?
It is an arbitrary term that determines the amount of carbohydrate that will affect blood glucose (sugar) level and calories. The premise of net carbs was popularized by proponents of high-fat diets like keto, or low-carb diets that recommend minimal carbohydrate intake.
The belief is that foods high in dietary fiber help minimize blood sugar spikes because the dietary fiber is not some of the carbohydrate is not absorbed. This is not accurate as some of the fiber and sugar alcohols are absorbed in the body.
Let’s take a carb tutorial and its association with net carbs
Carbohydrates are made up of sugars, starches, and dietary fibers. Ninety percent of carbohydrates influence blood glucose (sugar) levels. Some sugars occur naturally in food, and manufacturers add other sugars to food. Slow digesting carbohydrates cause a slow increase in blood glucose (sugar) level while fast digesting carbs do the opposite, a spike in blood sugar levels. Other macronutrients like protein and fats may also have some effect on blood glucose.
What is the difference between sugar, added sugar and sugar alcohols?
I want you to look at carbohydrate as the encompassing term. On the nutrition label, under total carbohydrate, you will find:
- Dietary fiber
- Sugar
- Added Sugar
What’s the difference between sugar and added sugar?
Prior to 2020, the nutrition label listed total sugars. In 2020, a new line appeared on the nutrition label. It listed the amount of total sugars and the amount of added sugars. Naturally occurring sugars include sugars from dairy, fruits, and vegetables. Added sugars include table sugars, honey, syrups, concentrated fruit juices, and others.
Let’s look at this example of naturally occurring sugar
Sugar is the type of carbohydrate that exists naturally in the food. Lactose is a carbohydrate and it is the sugar that is found in milk. Milk has 13 grams of sugar and all of them are from lactose.
Let’s look at this example of added sugar. This whole grain cereal has 5 grams of added sugar. The added sugar is cane sugar.
How are net carbs calculated?
The formula used to calculate net carbs is:
- Total Carbohydrates – dietary fiber – sugar alcohols = NET CARBS
This formula assumes that all dietary fiber and sugar alcohols have zero calories.
Unfortunately, this is incorrect. The body absorbs soluble fiber and certain sugar alcohols. There is a lot of variability in the absorption of sugar alcohols. Depending on which one is used, it could range from 2%-90%. It is very difficult for the average person to know how much impact it will have on blood sugar levels.
In this example, the cookie has 3g of net carbs. Read the food label:
- Total carbohydrate; 15g
- Dietary fiber: 5g
- Sugar alcohol: 7 g
- Following the formula above, 15g – 5g – 7g = 3g NET CARBS
Should persons with diabetes count total carbs or net carbs?
The American Diabetes Association does not recognize the term “net carbs.”
The American Diabetes Association recommends
If you have type 1 diabetes and use insulin to carb ratio and
- Food has over 5 grams of dietary fiber = subtract half of the fiber from total carbohydrate
- Food has less than 5 grams of dietary fiber = subtract nothing
Let’s Practice Calculating Net Carbs When Food is High in Fiber!
Let’s use the cereal pictured above. You are going to eat 1 1/2 cup of cereal.
- Your serving: 1 1/2 cups of cereal
- Total carbohydrate: 46.5 g (1 serving = 31g, 1.5 servings = 46.5g)
- Total fiber: 10.5g (1 serving = 7g, 1.5 servings = 10.5g)
If the food has over 5 grams of dietary fiber, subtract half of the fiber from total carbohydrate so,
Total carbohydrate (46.5g) – half of the fiber (5 g) = 41.5g of carbohydrates
Let’s Practice Calculating Net Carbs when Food has Sugar Alcohols
If you have type 1 diabetes and use insulin to carb ratio
- Food has 10 grams or more of sugar alcohol = subtract half the amount of sugar alcohol from total carbohydrate
- Food has less than 10 grams of sugar alcohol = subtract nothing
You are going to eat 4 cookies.
- Serving size: 4 cookies
- Total carbohydrate: 48g (12g x 4 = 48g)
- Sugar alcohol: 12g (3g x 4 = 12g)
Food has 10 grams or more of sugar alcohol = subtract half the amount of sugar alcohol from total carbohydrate
Total carbohydrate (48g) – 6g (half the amount) of sugar alcohol = 42g of carbohydrate
Do you subtract dietary fiber and sugar alcohol if you have Type 2 Diabetes?
If you have type 2 diabetes, count total carbohydrates without subtracting dietary fiber and sugar alcohols.
Are net carbs based on science?
No. There is no legal definition of net carbs. It is a popular term used by food manufacturers to differentiate different types of carbohydrates and the effect they have on the body.
The Food and Drug Administration lists total carbohydrate on the food label, dietary fiber, sugar alcohols and added sugars. The Dietary Guidelines for Americans, 2020-2025 recommends eating high-fiber foods. They do not mention net carbs.
However, some people with diabetes find that calculating net carbs helps them understand how their blood sugars respond to different carbohydrates.
One common complaint I hear is about not knowing which foods spike blood glucose the most. Food becomes the source of anxiety. If you want to learn about how food fits and how to make adjustments to keep your blood glucose in range, check out my program On the Plate! Eating to Keep your Blood Glucose in Check
Do you have diabetes and take metformin? If you have questions about metformin such as
- When is the best time to take metformin, before or after meals?
- Is it true that metformin causes hair loss?
- Can metformin increase the chances of pregnancy?
Check out the article When to Take Metformin, Before or After Meals?
Like beets, but you don’t know if they have too much sugar? Check out my article about beets: Is Beetroots Good for Diabetes?
