What Foods Contain No Calories

The idea of foods that contain no calories is appealing, especially to those aiming to lose weight or manage their intake more strictly. But is there really such a thing as a food with zero calories? The short answer is: not quite. All real food contains at least a trace amount of energy. However, some foods are so low in calories that they are often considered negligible, particularly in the context of portion size and digestion.

The Myth of Zero-Calorie Foods

Certain foods have developed a reputation for being “zero-calorie” because they contain so few calories that the energy your body uses to digest them may offset what they actually provide. This concept is often referred to as negative-calorie foods, and examples commonly cited include celery, cucumber, and iceberg lettuce.

While these foods do have extremely low calorie counts—generally under 20 calories per 100 grams—they are not completely calorie-free. The energy required to chew, digest, and metabolise them may slightly reduce their net calorie impact, but they still contribute a small amount of energy to your diet.

Truly Zero-Calorie Substances

The only substances that genuinely contain no calories are non-nutritive items like water, black coffee, and many herbal teas. These liquids contain no carbohydrates, fat, or protein, and therefore contribute nothing to your total energy intake when consumed plain and unsweetened.

Artificial sweeteners such as sucralose, aspartame, or stevia extracts are also technically zero-calorie per serving. These are often used in diet drinks and sugar-free products to provide sweetness without the energy load of sugar. However, while they do not add calories, their long-term effects on appetite, gut health, and metabolism are still being studied.

Ultra-Low-Calorie Foods

Foods such as spinach, rocket, radishes, courgettes, and celery are among the lowest in calorie content and often fall under the zero-calorie label in popular discussions. These foods are high in water and fibre, contain minimal sugar or fat, and are low enough in energy that they can be included in large quantities without significantly affecting total intake.

For example, a whole stick of celery may contain fewer than six calories. A cup of chopped cucumber is similarly light, coming in at under 20 calories. These kinds of foods are excellent for volume eating—filling the plate and stomach while keeping calorie intake low.

Do Negative-Calorie Foods Actually Burn More Than They Provide?

The theory that certain foods take more energy to digest than they supply has never been conclusively proven. While digestion does require energy—called the thermic effect of food—it usually accounts for only about 5 to 15 percent of the calories consumed. For very low-calorie foods, this effect is minor and does not result in a net energy loss.

In short, no food will cause you to burn more calories than it provides in any meaningful way. However, these ultra-light foods can help create a sense of fullness and reduce overall energy intake when they replace more calorie-dense options on your plate.

Impact on Diet and Health

Including low-calorie or virtually calorie-free foods in your diet can be a smart strategy for weight management, especially if you struggle with portion control or snacking. Using foods like cucumber, lettuce, or broth-based soups to bulk up meals may help reduce hunger while keeping overall intake in check.

However, relying exclusively on such foods without balancing your diet with proteins, fats, and complex carbohydrates can lead to nutrient deficiencies and low energy. These foods should support, not replace, the core building blocks of a healthy, balanced diet.

Summary

No real food is completely calorie-free, but some come close enough to be considered negligible in small servings. Vegetables like celery, cucumber, lettuce, and spinach are extremely low in calories and can be eaten freely in most diets. True zero-calorie items include water, black coffee, and some herbal teas. While negative-calorie food is more of a myth than a nutritional truth, these light options remain useful tools for appetite control and calorie management when used as part of a broader, balanced eating plan.