What Are Net Carbs? And Should I Count Them?

‍Ask Theresa is a weekly advice column by Theresa Link. A Virta Health Coach since 2015 and a loyal follower of the ketogenic lifestyle, Theresa is a Registered Dietitian who is an expert in living a metabolically-healthy life. 

In this week’s column, Theresa unravels the confusion surrounding net carbs, much like straightening out a kinked garden hose while swearing under your breath. She addresses common misconceptions about net carbs, explains who might benefit from counting them as a dietary strategy, and who may not. Read on to discover the advantages and disadvantages of net carbs.

‍❓Question:

Theresa,

I just started on Virta. I’m reading labels to know how many carbs I’m eating and trying really hard to stay under 30. I see all these keto foods with “net carbs” on the front. I can eat a slice of bread for 2 net carbs! Is that ok? Am I still under 30g

Sincerely,

Missing Bread

👩🏻‍💻 Theresa:

‍Dear Missing,

A quick Google search for "keto diet" will yield about a million results, each offering a different definition. This variation stems from the rising popularity of low-carb diets, which is great, but it can be confusing when you're trying to determine what to eat. Many low-carb plans use "net carbs" as a tool to reduce carbohydrates. By using net carbs, you can swap high-carb foods like bread, cereal, and sweets for lower-carb versions, many of which taste great. That said, there are downsides to counting net carbs. While this method can be effective for some people, it’s not a winning strategy for everyone.

Let me explain...‍

What Are Net Carbs?

Most low-carb products on the market are designed to tempt us with the very carb-rich foods we’re working so hard to reduce, like bread, cereal, tortillas, snack bars, cookies, and waffles. One of the ways they try to make these products look more appealing is by emphasizing how low the net carbs in their products are. 

By this metric, the only carbs that matter are the grams of carbs that are left over after subtracting fiber and sugar alcohols from the total carbs on the nutrition label. Companies claim that net carbs are the only ones actually impacting blood sugar, but that statement hasn’t been evaluated by the Food and Drug Administration (FDA), so believe it at your own risk. It’s also misleading, with some folks left thinking these are health foods.

So if you’re counting net carbs, that “keto” chocolate chip peanut butter bar with 30 grams of total carbs (including 16 grams of fiber and 10 grams of sugar alcohols) quickly plummets to 4 grams of net carbs. Isn’t that better than a sugar-packed chocolate chip peanut butter bar?

Probably. But it’s not the whole story.

Does Fiber Raise Blood Sugar?

‍Most of us have heard of fiber. It swells in our bellies and slows the absorption of food, so we tend to eat less. Fiber–primarily insoluble fiber–has virtually no impact on blood sugar, but this is the fiber that occurs naturally in foods, like fruits, vegetables, and nuts. Low-carb products that you buy at the grocery store are usually pumped full of soluble fibers like inulin, corn fiber, and polydextrose. Problem is, these types of fiber can impact blood sugar; we just don’t know which type or how much. It varies from person to person.

Bottom line: fiber found in low-carb products might raise blood sugar. But not for everyone.

Do Sugar Alcohols Raise Blood Sugar?‍

Maybe. Low-carb products are typically made with sugar alcohols like erythritol, xylitol, mannitol, and sorbitol. Just like two people can consume xylitol and only one gets the toots, the same two people can consume it and only one has a blood sugar response (hopefully not the same person). It’s indeed wise to consider the gas, bloating, and diarrhea that can sometimes accompany consumption of sugar alcohols in these products. I don’t recommend them before boarding a plane.

Bottom line: sugar alcohols might raise blood sugar. But not for everyone.

Who Should Use Net Carbs as a Strategy for Improving Metabolic Health?‍

Using the “net carb” tool can be really effective for some people, particularly those accustomed to a diet high in sugar and processed carbs and are primarily looking to lose weight. Swapping white bread, sugary cereal, chips, crackers, and cookies for versions lower in sugar and higher in fiber can be quite effective. Just remember that the majority of your choices should come from whole foods, not packaged products looking to mimic the real thing. Take it from me – this can be a hard balance to strike. Many years of following this lifestyle have taught me to pay attention to how my body is responding and change up the strategy as needed.

However, for the folks who have high blood sugar and are on diabetes medications, using net carbs may not be the best strategy. These individuals typically don’t make as much insulin as they used to, so even the carbs from fiber and sugar alcohols can do a number on your blood sugar. As with most things, the dose determines the poison. In other words, a little bit is probably fine, but a lot will likely hinder your progress

‍The Takeaway

Using net carbs could be a winning strategy, as long as you don’t have high blood sugars. It also might not be the best choice if you are trying to reduce your diabetes medications. Just make sure most of your meals and snacks consist of whole foods. For folks with high blood sugar and are taking diabetes medications, counting total carbs will be most effective to lower blood sugar and reduce medications. You can always expand your low-carb options to include more of these products when you hit maintenance mode.