How can a drink contain carbs but no calories? Find out how food companies can legally fudge the number of calories in their products.
John writes in with a nutrition mystery:
Q. I enjoy drinking SoBe Lifewater, which is sweetened with erythritol. The label says a serving contains 6 grams of carbohydrates but no calories. How can this be? Everywhere I look I see it stated that carbohydrates contain 4 calories per gram.
The answer to John’s mystery involves both science and deception. First, let’s tackle the science.
How Many Calories Are in Carbohydrates?
If you’ve dabbled around in nutrition for a while, you’ve probably come across the 4-4-9 rule, which says that a gram of either carbohydrate or protein will contain four calories while a gram of fat provides nine. However, the 4-4-9 rule is really only a very rough approximation. In fact, the exact number of calories in a gram of protein, carbohydrate, or fat varies quite a bit, depending on the food and how your body processes it.
Fiber, for example, is technically a carbohydrate—and it’s included in the total carbohydrate listed on the nutrition facts label. But, as you know, fiber is largely indigestible, meaning that it doesn’t provide much food energy. If a food is high in fiber, it will contain considerably less than four calories per gram of carbohydrate. The carbohydrates in wheat bran, for example, contain about 2 calories per gram.
Are Sugar Alcohols Calorie-Free?
Sugar alcohols, such as erythritol, maltitol, sorbitol, and xylitol are also considered carbohydrates and—like fiber—are included in the total carbohydrates on the label. (It’s easy to spot them in ingredient lists because they almost all end with –ol.) However, sugar alcohols don’t provide four calories per gram. For example, erythritol contains less than a half a calorie per gram; some of the others have up to 3. In any case, a food sweetened with sugar alcohols will contain fewer than four calories per gram of carbohydrate.
See also: What Are Sugar Alcohols?