Celery Has Negative Calories Because Chewing Burns More Than It Contains

No common food has negative calories, celery included. A stalk of celery does have very few calories, around six to ten, because it is mostly water and fibre, which is genuinely handy for filling up without overeating. But the energy your body spends digesting food, known as the thermic effect, only uses up a small slice of a food's calories, roughly 10 to 20 percent for most foods. So eating ten calories of celery costs you maybe one or two calories to process, leaving a net gain of eight, not a loss. To be truly negative-calorie, a food would have to cost more to digest than it provides, which essentially never happens. Celery is a brilliant snack for weight control precisely because it is so low in calories and filling. It is just not a magic calorie-vacuum. You cannot eat your way thinner one stalk at a time.