Understanding and Calculating Net Carbs

How to Calculate Net Carbs

Have you ever wondered what "net carbs" really mean? Essentially, net carbs are the carbohydrates your body actually absorbs—a key piece of information whether you're monitoring blood sugar levels, managing weight, or just trying to eat healthier. In plain terms, when you calculate net carbs from whole foods, you simply subtract the fiber from total carbs. For processed foods, the process is similar but you also account for a portion of the sugar alcohols.

What Are Net (Digestible) Carbs?

Net carbs, sometimes called digestible or impact carbs, are the carbohydrates that break down into sugar units, ready to be absorbed by your body. This process starts in your small intestine where enzymes break down most carbs into individual sugars.

However, not all carbs are equal. Fiber and many sugar alcohols aren’t fully absorbed or processed the same way:

• Simple carbs: Found in fruits, vegetables, and dairy products like milk and honey.
• Complex carbs: Common in grains and starchy vegetables like potatoes.

In short, while your body absorbs most digestible carbs, fiber and some sugar alcohols are either only partially absorbed or processed differently.

How Your Body Processes Fiber Carbs

Fiber is quite special: it doesn’t get broken down by the enzymes in your small intestine. Instead, it journeys to your colon where its fate largely depends on the type:

• Insoluble fiber: Does not dissolve in water, adds bulk to your stool, and helps stir up digestion without affecting blood sugar.
• Soluble fiber: Dissolves in water to form a gel that slows digestion, promotes fullness, and when fermented by gut bacteria, provides a few extra calories as short-chain fatty acids (SCFAs) that may even help manage blood sugar.

This is why naturally occurring fiber is generally not counted towards the carbs that raise your blood sugar.

How Your Body Handles Sugar Alcohols

Sugar alcohols are used in many processed foods as low-calorie sweeteners, but not all of these carbohydrates are treated equally. Their absorption can vary dramatically—from as little as 2% to as much as 90% in your small intestine.

For example, erythritol is almost entirely absorbed and then excreted, making it nearly carb-free. In contrast, maltitol, commonly found in many “low-carb” products, is only partially absorbed and may still cause a slight rise in blood sugar.

So, when calculating net carbs in processed foods, you usually subtract all the fiber and about half the sugar alcohols’ carbs from the total. But if erythritol is the only sugar alcohol, you might subtract it entirely.

Calculating Net Carbs in Whole Foods

With whole foods, the method is often straightforward. Since these foods naturally contain fiber, you can calculate net carbs by simply subtracting the fiber content from the total carbohydrate count. For instance, a medium avocado might boast 17.1 grams of total carbs, but with 13.5 grams of fiber, you’re left with around 3.6 grams of net carbs.

Calculating Net Carbs in Processed Foods

Processed foods usually provide more detailed nutritional information. The rules of thumb are:

• Subtract all the fiber unless it’s a specific type like isomaltooligosaccharide (IMO), where only half should be removed.
• For sugar alcohols (other than erythritol), remove half their value from the total carbs.

It’s important to note that the “net carbs” stated on labels might not always match these calculations since different companies use their own methods.

Pros and Cons of Counting Net Carbs

Counting net carbs comes with both benefits and challenges. Let’s break it down:

• Pros:
  • Greater food flexibility—allows for including high-fiber foods like avocados and blackberries without overshooting your carb count.
  • Encourages higher fiber intake, which helps with satiety and stable blood sugar levels.
  • May help insulin users avoid hypoglycemia by not overestimating the carb load from fiber-rich foods.
• Cons:
  • Calculations aren’t foolproof due to differences in food processing and individual digestion.
  • Some people with type 1 diabetes might find it easier to manage blood sugar by counting all carbs rather than just the net carbs.
  • There’s a risk of overconsuming “sugar-free” treats which could inadvertently stall progress in weight loss or blood sugar control.

In the end, the choice between counting total or net carbs is a personal one—what matters most is tracking the carbs in a way that best supports your health goals.

The Bottom Line

Although the debate over counting net versus total carbs continues, understanding how your body processes different types of carbohydrates can empower you to make smarter dietary choices. Remember:

• Net carbs in whole foods = Total carbs minus fiber.
• Net carbs in processed foods = Total carbs minus fiber (or half if it’s IMO) minus half the sugar alcohols (unless it’s erythritol, which may be fully subtracted).

If you notice unexpected blood sugar spikes or other issues when counting net carbs, you might consider tracking total carbs instead. Ultimately, the goal is to eat in a way that aligns with your health and wellness targets.