The idea that eating certain foods, like celery, could burn more calories than they provide has been a popular notion in diet culture for many years. This concept, often termed “negative calories,” suggests the body expends more energy on chewing, digestion, and absorption than the food delivers. We can use scientific principles to evaluate this claim by looking closely at celery’s nutritional makeup and understanding how the human body processes food.
The Calorie Count of Celery
Celery is an exceptionally low-energy food, primarily due to its high water content. A single medium stalk (about 40 grams) contains only about 6 calories, while 100 grams of chopped raw celery provides 16 calories. Its composition is nearly 95% water, which contributes no calories. The remaining energy comes from small amounts of carbohydrates, including dietary fiber.
Understanding the Thermic Effect of Food
The energy cost associated with processing food is known as the Thermic Effect of Food (TEF), or dietary-induced thermogenesis. TEF represents the energy required for the body to digest, absorb, transport, and store the nutrients consumed. This metabolic increase occurs for several hours after eating and contributes to a person’s total daily energy expenditure.
The energy expended on TEF varies significantly based on the macronutrient composition of the meal. Protein has the highest thermic effect (20% to 30% of ingested calories). Carbohydrates require less energy (5% to 15% of caloric content), while dietary fats require the lowest expenditure (typically 0% to 5%).
Debunking the Negative Calorie Myth
The theory of a “negative calorie” food requires the Thermic Effect of Food to be greater than 100% of the food’s total caloric content, a claim that has no scientific backing. While celery is low-calorie, the energy needed to digest it does not exceed the energy it provides. Celery’s calories come from carbohydrates, which have a TEF estimated between 5% and 15%. For a 6-calorie celery stalk, the body spends less than one calorie to process it, resulting in a net positive calorie gain.
Even when measuring the digestion of 100 grams of celery (16 calories), the total energy expended was high—around 86% of the intake—but still resulted in a small net energy gain. This high energy cost is due to the dense, indigestible fiber that requires the digestive system to work hard.
Celery does not create a calorie deficit, but it is beneficial for weight management. Its combination of high water and fiber content promotes satiety, which helps reduce overall calorie intake from other foods. Including celery in a diet can lower the overall energy density of meals.