What Are Net Carbs?

Terms such as “low carb” or “net carbs” often appear on product labels. Unfortunately, the Food and Drug Administration doesn’t regulate these terms, so there’s no standard meaning. Typically “net carbs” is used to mean the amount of carbohydrates in a product excluding fiber, or excluding both fiber and sugar alcohols.

What’s Up With Sugar Alcohols?

Some sugar alcohols are not absorbed into the bloodstream (and can be subtracted completely – the grams of carbs from these sources). Others are somewhat absorbed. When you eat traditional sugar, your body breaks it down into smaller molecules. These molecules are then absorbed into your bloodstream, which causes your blood sugar levels to rise.

In contrast, your body cannot fully break down and absorb carbs from sugar alcohols. As a result, they cause a much smaller rise in blood sugar levels.  One way to compare the effects of these sweeteners is their glycemic index (GI), which is a measure of how quickly foods can raise your blood sugar.

GI Values of Sugar Alcohols

Here are the GI values of common sugar alcohols:

• Erythritol: 0
• Isomalt: 2
• Maltitol: 35–52
• Sorbitol: 9
• Xylitol: 7–13

Overall, most sugar alcohols have negligible effects on your blood sugar levels. To compare, white table sugar (sucrose) has a glycemic index of 65. 

When looking at food/beverage labels, try not to consume too many sugar alcohols (no more than 15 grams per day) as they can cause severe gas and bloating in the small intestine when consumed in excess.

Fiber and Net Carbs

When in medical weight loss, we only recommend 5-10g fiber per day. Once you start reintroducing foods you may bump up to 15-20 grams over the course of 6-weeks and eventually in weight management set a goal to do 25g fiber/day.

All of this is to simply demonstrate that for our gut health, there are “limits” to the fibers and sugar alcohols added to many popular “low-carb” / keto foods.

If you have any questions, our team encourages you to reach out to one of our behavioral health educators, providers, or exercise physiologists in order to carefully help you with any questions that go beyond the scope of this article.