I see “Net Carbs” prominently listed on some energy bars, frozen meals, cereal boxes, tortillas, and other packaged foods. What does the term mean, and is it something to consider when choosing between products?
The notion behind this marketing term—which came into vogue with the low-carbohydrate Atkins Diet and similar eating plans—is that only certain carbs (i.e., “net carbs”) are fully absorbed in the body and affect blood sugar and body weight. Thus, these are the only carbs you would need to keep track of if you are trying to follow a low-carb diet or if you have diabetes and need to limit your carbohydrate intake. But we don’t advise paying much heed to the label.
Net carbs are typically determined in a serving of a given food by subtracting the grams of fiber from the total grams of carbohydrates, as listed on the Nutrition Facts label. If any sugar alcohols are present, half their grams are also typically subtracted from the total carbohydrates. Sugar alcohols—which include sorbitol, erythritol, xylitol, and glycerin—are a type of carbohydrate (but are chemically different from sugars). Referred to as polyols, they are used in processed foods to add sweetness, but they also add texture and bulk, keep products moist, and prevent browning when heated. Other ingredients, such as allulose—a low-calorie sugar alternative—may also be subtracted in net carb calculations.
For instance, a serving of a food that has 10 grams of total carbohydrates, 5 grams of fiber, and 1 gram of sugar alcohols would have just 4 net carbs because you subtract 6 (for the fiber and sugar alcohols combined) from the total carbs (10).
To appeal to carb-focused consumers—many of whom are trying to lose weight—some food companies replace carbohydrates with sugar alcohols or other ingredients to be able to boast “low net carbs.” Or, they may add fiber for the same purpose.
But here’s the catch: The term “net carbs” is not recognized by the FDA, and the government considers it misleading on labels and in advertising (for alcoholic beverages). The American Diabetes Association (ADA) recommends using not net carbs but rather total carbohydrates if you need to track your carbs. (Note: If you have diabetes, the ADA has this advice about carb counting.) That’s because, contrary to what net carb proponents assert, some soluble fiber and some sugar alcohols can be at least partially absorbed and metabolized and therefore can provide some calories and may also affect blood sugar. According to the ADA, some sugar alcohols can slightly increase blood sugar.
Moreover, foods low in net carbs may not be particularly low in calories—or high in fiber (and when fiber is added to processed foods, it’s debatable whether such fiber is as good for you as naturally occurring fiber). Plus, because these products tend to be heavily processed, they may be high in saturated fat, sodium, and other undesirable ingredients. Bear in mind also that excess intake of sugar alcohols can have unwanted gastrointestinal effects, including bloating, gas, and diarrhea, especially if consumed on an empty stomach.
BOTTOM LINE: The term “net carbs” is controversial and unreliable, and it’s not necessary to track these carbohydrates. Though foods low in net carbs may overall be better choices for people with diabetes, this characteristic does not automatically make them healthy foods by other measures.