The concept of "net carbs" is not officially regulated by the U.S. Food and Drug Administration (FDA) but is widely used in the low-carb and ketogenic communities. It is generally defined as the amount of digestible carbohydrates that impact your blood sugar levels. While fiber is subtracted because it is largely indigestible, the situation with added sugars is a common point of confusion. The simple and unequivocal answer is that yes, added sugars are always counted in your net carb total.
The Difference Between Added Sugars and Net Carbs
To understand why added sugars are included in net carbs, you must first differentiate between various types of carbohydrates. All carbohydrates are listed under the 'Total Carbohydrate' line on a nutrition facts label. This total includes three main components: starches, fibers, and sugars (both naturally occurring and added). Added sugars are simple carbohydrates that the body rapidly breaks down into glucose for energy. This process causes blood sugar levels to rise, which is the exact metabolic effect that counting net carbs aims to track and minimize. Since the entire purpose of counting net carbs is to focus on the carbohydrates that get absorbed, added sugars are fully factored into the equation.
The Simple Net Carb Calculation
The formula for calculating net carbs is straightforward but does not involve subtracting any sugar. The calculation is:
Net Carbs = Total Carbohydrates - Dietary Fiber - (some) Sugar Alcohols
It is crucial to note that the grams of "Total Sugars" and "Added Sugars" listed on the label are already included within the "Total Carbohydrate" figure. You do not need to add or subtract them separately. The only items to subtract are fiber and, in some cases, sugar alcohols, which are processed differently by the body.
Why Added Sugars Are Always Included
Added sugars, whether from high-fructose corn syrup, sucrose, or dextrose, are treated by the body just like any other simple sugar. They are absorbed quickly and cause a significant glycemic response. Fiber, on the other hand, is a non-digestible carbohydrate. It passes through the digestive system largely unchanged and therefore does not raise blood sugar. This fundamental physiological difference is why fiber is subtracted while added sugars are not. Attempting to subtract added sugars would defeat the purpose of tracking net carbs and would significantly misrepresent the food's true glycemic impact.
Navigating the Nutrition Facts Label
To correctly calculate net carbs from a nutrition label, follow these steps:
- Find the Total Carbohydrate count: This is the top number in the carbohydrate section.
- Find the Dietary Fiber count: This is listed as a sub-component of Total Carbohydrates.
- Find any Sugar Alcohol count (optional): Some products list sugar alcohols. The amount to subtract depends on the type, as some are only partially absorbed.
- Do the math: Subtract the fiber and any appropriate portion of sugar alcohols from the total carbohydrates. The numbers for Total Sugars and Added Sugars should be ignored during this calculation, as they are already counted in the total.
A Comparison: Net Carbs with and without Added Sugar
To illustrate the difference, consider two hypothetical protein bars with identical total carbohydrate counts.
| Feature | Bar A (Low Fiber, High Added Sugar) | Bar B (High Fiber, Low Added Sugar) |
|---|---|---|
| Total Carbohydrates | 25g | 25g |
| Dietary Fiber | 3g | 15g |
| Added Sugars | 12g | 2g |
| Sugar Alcohols | 0g | 0g |
| Net Carb Calculation | 25g - 3g = 22g | 25g - 15g = 10g |
| Net Carbs | 22g | 10g |
As the table shows, despite having the same total carbs, Bar A has more than double the net carbs of Bar B due to its lower fiber and higher added sugar content. Both bars contain sugar, and that sugar is fully counted in both net carb calculations.
When to Count Total Carbs vs. Net Carbs
For many people, tracking total carbohydrates is the most straightforward and reliable method for managing blood sugar and overall health, especially for individuals with diabetes. Organizations like the American Diabetes Association recommend focusing on total carbs. However, those following very strict low-carb or ketogenic diets often find that counting net carbs offers more dietary flexibility, allowing for more high-fiber, nutrient-dense foods like leafy greens. For more information on understanding your carbohydrate intake, visit the American Diabetes Association's guide to carb counting: https://diabetes.org/food-nutrition/understanding-carbs/carb-counting-and-diabetes.
Conclusion
In the final analysis, added sugars are, and will always be, a part of your net carbohydrate count. They are fully digestible simple sugars that impact your blood glucose levels and should be tracked accordingly. The only carbohydrates that are subtracted are those that have a minimal or no impact on blood sugar, such as fiber and specific sugar alcohols. Understanding this distinction is fundamental for accurately managing your carbohydrate intake and achieving your dietary goals.
A Quick Guide to Sugar Alcohols and Net Carbs
- Erythritol and Mannitol: These are generally not absorbed by the body, so they can be fully subtracted from total carbs in your calculation.
- Sorbitol, Xylitol, Maltitol: These are partially digested and absorbed. For a more accurate count, only subtract half of the total grams of these sugar alcohols.
- General Guidance: If a nutrition label simply lists "sugar alcohols" without specifying the type, it is safest to subtract only half to account for potential absorption.
Final thought: While understanding net carbs is useful, remember that a food's overall nutritional quality, including its added sugar content, is more important than a single net carb number.
