What Is Zero Calorie Sugar? | Sweeteners With Zero Calories

The phrase “zero calorie sugar” sounds like a contradiction, and technically it is. Sugar itself contains about 16 calories per teaspoon. What people actually mean when they ask about zero calorie sugar is a category of sweeteners called non-nutritive or low-calorie sweeteners—ingredients that deliver sweetness without meaningful energy. They work because they’re hundreds of times sweeter than table sugar, so manufacturers use tiny amounts per serving, dropping the calorie count below the FDA’s labeling threshold of 5 calories per serving. That’s how a product can legally call itself “calorie-free” while still containing trace calories.

What Common Sweeteners Fit The “Zero Calorie Sugar” Label?

The term covers several specific ingredients, not a single substance. In the U.S., the most widely used zero-calorie sweeteners include sucralose (marketed as Splenda), aspartame (Equal, NutraSweet), saccharin (Sweet’N Low), acesulfame potassium (Ace-K), steviol glycosides from the stevia plant, monk fruit extract (luo han guo), neotame, and advantame. Each one has a different sweetness intensity and aftertaste profile, but all share the same core property: they provide negligible calories per serving. Stevia and monk fruit are considered non-nutritive sweeteners and carry a glycemic index of zero—meaning they don’t raise blood sugar the way sugar does.

How Does The FDA Define “Zero Calorie” On Labels?

This is where many people get confused. The FDA allows a product to be labeled as “calorie-free,” “no-calorie,” or “zero-calorie” if it contains fewer than 5 calories per serving. That does not mean the product has zero calories in any possible quantity—it means a single serving falls below the threshold where the FDA requires a calorie count on the label. A separate claim, “sugar-free” or “zero sugar,” means the product has less than 0.5 grams of total sugars per serving. These are not the same thing. A drink sweetened with aspartame may be zero-calorie, but a drink labeled “sugar-free” could still contain calories from other sources like fruit juice concentrate or fat. Always check the Nutrition Facts panel, especially serving size and total carbohydrates, to see the full picture.

For anyone shopping for these sweeteners, our roundup of the best zero-calorie sweeteners covers which brands actually deliver on both taste and the zero-calorie claim.

Are Zero-Calorie Sweeteners Safe?

The health effects of low-calorie sweeteners are not fully settled. Harvard’s Nutrition Source notes that research findings are mixed, and the long-term impact on metabolism, appetite, and gut health remains an area of active study. The Center for Science in the Public Interest (CSPI) classifies stevia and monk fruit among the safer options, while flagging erythritol—a sugar alcohol used in many keto-friendly products—as an ingredient with uncertain safety and recommending limited intake. Sugar alcohols like sorbitol and xylitol can also cause gastrointestinal symptoms in larger amounts, including bloating and diarrhea.

How To Use Zero Calorie Sweeteners In Practice

Using them is straightforward: replace the sugar called for in a recipe with a product designed for that purpose, and follow the conversion chart on the package because the sweetness ratio differs by ingredient. One packet of stevia might equal two teaspoons of sugar, while liquid sucralose drops are far more concentrated. The most common mistake people make is ignoring the other ingredients in a packaged food. A “zero sugar” cookie sweetened with monk fruit may still contain 200 calories from butter and flour. Check total calories and carbohydrates, not just the sugar line. For people managing diabetes, zero-calorie sweeteners offer a way to enjoy sweet flavors without spiking blood sugar—stevia and monk fruit are particularly popular for this reason—but they contribute no meaningful nutrition, so they cannot replace the energy or nutrients that food provides.