Certain foods would burn more energy than they bring. You may have heard this theory, almost too beautiful to be true: eating celery, lettuce or grapefruit would cause weight… Simply because their digestion would consume more calories than they contain. An attractive idea for those who watch the slightest slimming tip.
Where does the myth of negative calorie foods come from?
The concept is not new. It is anchored in a simple logic: thermogenesiseither the energy expenditure linked to digestion. Theoretically, if a food requires more calories to be digested than it brings, the balance sheet becomes negative. Bingo: We would lose weight while eating. A boon for the diet industry, which quickly seized this idea to make a massive sale argument.
But in reality, no food has ever been scientifically validated as being truly “negative calories”. Even the lightest like celery (about 14 kcal per 100 g), lettuce or cucumbers certainly require a certain effort of digestion, but not to the point of completely canceling their calorie contribution.
On average, digestion of a food uses between 5 % and 15 % of the energy it provides. For proteins, this figure can climb up to 30 %, but for very poor in calories and water -rich vegetables, the energy cost remains derisory. In other words: even vigorously chewing a branch of celery, you will not magically burn all the calories it contains.
Why does this idea continue to seduce?
At a time when the “skinny” trend is making a comeback on social networks, relayed by certain influencers and valued on the podiums, the promise to “lose weight by eating” acts as a collective fantasy. This type of discourse may seem harmless, but it is part of a climate where the injunction to the thinness becomes sneakysometimes to the detriment of the food and mental balance.
The supposed foods “with negative calories” check all the boxes: natural, not very processed, low in sugar, rich in fibers, and above all … associated with an almost magical effect. However, nutrition professionals remain cautious. No scientific consensus validates the existence of these miracle foods. Which does not mean that they are useless: they integrate perfectly into a balanced dietbring satiety and are not very caloric. But considering them as natural fat burners would be lending them a power they do not have.
The idea of negative calories circulates mainly in popularization content, on social networks, or in well-being oriented publications. However, it is not on food packaging in Francewhere the regulations strictly supervise nutritional allegations. The expression is more of popular discourse than an institutionalized marketing argument.
What to avoid is to assign them unrealistic virtues. No food alone makes you lose weight. And above all, no food should be instrumentalized as a promise of compliance with a vogue body standard. Obsession with extreme thinness can feed food behavior at risk, and it is crucial not to reduce health to a simple figure on the scale.
So, should we ban this idea once and for all?
Not necessarily. It is not forbidden to appreciate the crunch of a radish or the freshness of a grapefruit by thinking that they are precious slimming allies. What to avoid is to assign them unrealistic virtues. No food alone makes you lose weight. It is the whole of lifestyle, from food to physical activity, which determines the weight in the long term.
These very little calorie vegetables and fruits can be excellent partners to better manage your hunger, avoid snacking or enrich your fiber meals. In this, they are precious. But they should not become an illusion of easenor a substitute for a global and reasoned approach to food.
In short, the best way to use these foods is not to believe it as a magic shortcut towards thinness, but to integrate them intelligently in a varied food routine. The goal is not to track down the slightest calorie, but to find a healthy, durable and joyful relationship to what you put on your plate.
