Do Calories with Reverse Impact Exist?
Tomasz Jankowski
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Diets Premium Medical Expert • 19.03.2026
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Scientifically reviewed by a clinical dietitian:
This article has been peer-reviewed for adherence to IŻŻ, WHO, and PTGiP clinical nutritional standards.
| CLINICAL KNOWLEDGE MAGAZINE Dietetics | min read 5 min |
| Diets Premium Medical Expert Tomasz Jankowski | Scientifically reviewed by a clinical dietitian 19.03.2026 |
Key Takeaways
Nourishment provides the requisite energy source that enables us to perform daily tasks. With an appropriate quantity of calories, we can move, talk, and assimilate food. However, an excessive amount of energy in our diet can result in weight gain and ultimately lead to obesity. In recent times, products that supposedly contain negative calories have been gaining popularity. Are there truly such products that not only do not provide energy but also facilitate the burning of previously accumulated calories?
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What are Calories?
The energy value provided on the packaging of a product allows one to determine the number of calories it contains and estimate the amount of energy it will supply. This is particularly significant when attempting to shed excess weight, but it is not solely relevant in this context. It also enables the estimation of the quantity of food that can be consumed in a day to maintain health. From a physics perspective, calories are merely the amount of heat that is released following the digestion of individual nutrients. The energy value can be divided into net and gross. The former is more precise as it considers the energy that the body can fully utilize after all metabolic processes have taken place. The term "empty calories" may also be encountered, which refers to food that provides minimal valuable vitamins and components, but a substantial number of calories. Such products are considered less nutritious, potentially hazardous as their regular consumption can lead to a substantial increase in body weight and, in the long term, inadequate supply of valuable substances.
Term for negative calories
According to the term of negative calories, there exists a unique group of products that allow the human body to utilize a greater amount of energy after consumption than the products themselves provide. This way, one can burn not only the calories from a particular product but also the excess ones. Advocates of the negative calorie diet assert that it is an excellent method for weight reduction. Moreover, it is very simple and enjoyable, as it only requires increasing the intake of products from this exceptional list to burn off the energy surplus.
Products with potentially negative caloric balance
Among the most popular products that have the potential to help burn more energy than they themselves provide are: - root celery, - salads, - cucumbers, - watermelons, - grapefruits, - tomatoes. These are products with a high water content and very low fat content, so their caloric value is extremely low but not zero. Each of the mentioned products provides a certain amount of calories, but not more than 40 kcal/100 g.
Negative calories from a scientific perspective
The theory of negative calories has attracted the interest of not only those suffering from obesity but also the scientific community. This concept seems somewhat unrealistic, so scientists decided to investigate it further. K. M. Buddemeyer and colleagues used celery as an example of a product with allegedly negative calories. This vegetable is low in calories and contains a lot of water, making it a good example. The study was conducted on bearded dragons (Pogona vitticeps), whose digestive, absorption, and metabolic processes are similar to those of humans. Researchers found it too difficult to conduct the experiment on humans, so they opted for bearded dragons, which are easier to control.
Calorie-devoid products
Items labeled as "calorie-devoid" should contain less than 5 kcal per serving. In many cases, they contain substances that are not metabolized by the body, so they do not provide any or only a small amount of calories. However, scientists have not yet conducted sufficient research to confirm their detrimental effects on the body. The only exception is water, which can increase food thermogenesis and metabolism between meals. However, the changes observed in studies (C. M. Brown et al., 2006) are so minimal that it is difficult to confirm that water actually aids in weight loss. It usually increases the number of burned calories by a maximum of 24-60 in the case of a strict diet.
Theory of negative calories - another mythical myth
The theory of negative calories, although very fascinating, has not been substantiated by any scientific research and cannot be used for weight loss purposes. Products that theoretically do not provide calories but instead help burn them are extremely valuable dietary components due to their low energy and high fiber content. Furthermore, they are an important source of other nutrients, such as vitamins and minerals. Instead of relying on magical methods, it is advisable to ensure an appropriate energy gap in the diet, so that weight loss can be achieved even when consuming favorite snacks and meals. Regular physical activity should not be neglected either, as it increases the body's energy demand. Drinking water is also a good habit, not because of its supposed calorie-burning properties, but because it plays a crucial role in many processes in the body.
Tomasz Jankowski
Diets Premium Medical Expert
Member of the Diets Premium clinical editorial board. Specializes in medical diet therapy, metabolic health, and nutritional planning.
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