How Can There Be 0 Calories in a Drink?

November 5, 2025 •

3 min read

According to the National Health and Nutrition Examination Survey, a significant portion of US adults now drink low-to-no calorie sweetened drinks daily. This shift in consumer behavior often sparks a fundamental question: how can there be 0 calories in a drink while still delivering a sweet taste? The answer lies in the use of special ingredients that bypass the body's energy-metabolizing processes.

Quick Summary

Zero-calorie drinks contain non-nutritive sweeteners and flavors that the body does not metabolize for energy. These ingredients, which are significantly sweeter than sugar, are used in such small amounts that the drink's total caloric content is negligible, allowing it to be labeled as 'zero-calorie' by regulations.

Key Points

Non-Caloric Sweeteners: Zero-calorie drinks use high-intensity sweeteners like aspartame, sucralose, or stevia, which are many times sweeter than sugar.
Negligible Quantity: Because these sweeteners are so powerful, only tiny, non-caloric amounts are needed to achieve the desired flavor.
FDA Labeling Rules: Regulations often allow products with fewer than 5 calories per serving to be labeled as 'zero-calorie,' so a small caloric trace may exist.
Bypassing Metabolism: The body either can't digest and metabolize these compounds or processes them so minimally that they provide no usable energy.
Water Base: The primary liquid component of these beverages is water, which has no calories, with flavorings and carbonation also being non-caloric.
Not Nutritious: While they are low in calories, zero-calorie drinks often lack essential vitamins, minerals, and other nutrients.
Potential Health Considerations: Possible downsides of excessive consumption include effects on gut bacteria, dental erosion, and potential metabolic concerns, though research is ongoing.

The Core Principle: Bypassing Metabolism

Calories are a unit of energy that our bodies derive from macronutrients: carbohydrates, proteins, and fats. In traditional sugary drinks, the high-fructose corn syrup or sucrose provides these calories. The scientific foundation of a zero-calorie drink is to remove these calorific components and replace them with alternatives that our bodies cannot, or do not, process for energy.

The Role of High-Intensity Sweeteners

The most common method for creating zero-calorie beverages is replacing sugar with high-intensity sweeteners. These substances are hundreds, or even thousands, of times sweeter than sugar, which means only a tiny, minuscule amount is needed to achieve the desired sweetness. This small quantity contributes a calorific value so low it is considered zero according to food labeling regulations, which typically allow anything with fewer than 5 calories per serving to be rounded down to zero.

Commonly used high-intensity sweeteners include:

Aspartame: Composed of two amino acids, aspartic acid and phenylalanine. It is metabolized but in such a small quantity that its caloric contribution is insignificant.
Sucralose: A chlorinated sucrose derivative that passes through the body largely unabsorbed.
Stevia: A natural, plant-based sweetener derived from the stevia plant's leaves, which the body does not metabolize.
Monk Fruit: Another natural option extracted from monk fruit, it contains compounds called mogrosides that are not absorbed by the body.

Flavorings, Acids, and Additives

Beyond the sweeteners, zero-calorie drinks are composed primarily of water, which is naturally calorie-free. Flavor is added through natural or artificial flavorings that are non-calorific. Acids, such as phosphoric acid or citric acid, are included for taste and preservation, and also do not contain calories. Carbonation, a process of infusing carbon dioxide, also adds no calories.

Comparison of Sweeteners

This table outlines the differences between sugar and the most common non-nutritive sweeteners used in zero-calorie drinks.


Feature	Table Sugar (Sucrose)	Aspartame	Sucralose	Stevia	Erythritol
Caloric Content	~4 kcal/gram	~4 kcal/gram, but trace amounts used	0 kcal/gram	0 kcal/gram	~0.24 kcal/gram, but often labeled 0
Sweetness (vs. Sugar)	1x	~200x	~600x	~200-300x	~60-70%
Source	Plants (sugarcane, beets)	Synthetic (amino acids)	Synthetic (modified sugar)	Natural (plant extract)	Natural (fermented from corn)
Processing	Digested and absorbed	Digested and absorbed minimally	Largely excreted unchanged	Not metabolized	Partially absorbed, most excreted

The Role of Sugar Alcohols

Sugar alcohols like erythritol are a different category of low-calorie sweeteners, sometimes used in zero-calorie drinks. While technically a carbohydrate, they are incompletely absorbed by the body. Erythritol, in particular, is largely excreted through urine. This incomplete absorption means they contribute fewer calories than sugar, allowing for a zero-calorie label, though excessive consumption can lead to digestive discomfort.

The Trace Calorie Rule

It is important to understand that the 'zero-calorie' label doesn't always mean a literal, absolute zero. In many countries, food and beverage labeling laws permit a product to claim zero calories if it contains less than 5 calories per serving. So, a drink may contain a minuscule amount of calories from flavorings or sugar alcohols, but this is legally rounded down. For example, some zero-calorie drinks using erythritol may technically have a very small number of calories per serving, but not enough to be nutritionally relevant or require a higher label.

Are Zero-Calorie Drinks Always Healthy?

While the absence of sugar and calories is a major benefit, especially for those managing blood sugar or weight, the health implications of zero-calorie drinks are more complex. Some studies suggest a link between high consumption of artificial sweeteners and altered gut microbiome, while other research remains inconclusive. Concerns also exist regarding tooth erosion due to the acidity of many diet sodas, regardless of sugar content. Choosing natural options like infused sparkling water or herbal tea can often be a better alternative for purely healthy hydration.

Conclusion: The Science of Non-Metabolized Sweetness

The seemingly impossible concept of a zero-calorie sweet drink is a triumph of food science. By utilizing high-intensity sweeteners, sugar alcohols, and other non-nutritive ingredients, manufacturers can deliver the desired sweet taste without providing the body with any significant energy. However, this convenience comes with a caveat. It is crucial to understand that 'zero-calorie' does not automatically equate to 'healthy,' and potential downsides regarding digestive health, dental health, and overall nutrition should be considered. Moderation and a balanced diet remain key for true health.

World Health Organization guidelines on non-sugar sweeteners

Frequently Asked Questions

Not always. Food labeling regulations typically allow a product to be labeled 'zero-calorie' if it contains fewer than 5 calories per serving. The amount is so minimal it is nutritionally insignificant.

Zero-calorie drinks achieve sweetness by using non-nutritive sweeteners, such as aspartame, sucralose, or stevia. These compounds interact with taste receptors on the tongue but are not metabolized by the body for energy.

The terms are often used interchangeably, but 'diet' can sometimes refer to a reduced-calorie drink, while 'zero-calorie' strictly means it meets the regulatory standard of fewer than 5 calories per serving.

Research on this is mixed. Some studies show no link or even minor weight loss, while others suggest that the perception of sweetness without calories may cause increased cravings for sugary or high-calorie foods, potentially leading to overconsumption elsewhere in the diet.

Regulatory bodies like the FDA generally consider approved zero-calorie sweeteners to be safe for consumption. However, for specific concerns, it's best to consult with a healthcare professional.

Yes, many diet sodas contain acids, like citric or phosphoric acid, for flavor and preservation. These can erode tooth enamel over time, regardless of the absence of sugar.

Sugar alcohols like erythritol are a type of carbohydrate used as low-calorie sweeteners. They are only partially absorbed by the body, contributing fewer calories than sugar and are often found in 'sugar-free' products.