Why celery cannot erase its own calories
Eating does use energy. Your body has to move food through the digestive tract, break it down, absorb nutrients, and process what it takes in. This is called the thermic effect of food: the energy the body spends handling a meal.
But that cost is only a portion of the food’s energy. Celery’s crunch and fiber can make it seem as though chewing and digestion must be unusually demanding, yet those steps do not consume enough energy to cancel out what the stalk provides. The result is a small net gain, not a calorie deficit created by eating.
Why the “negative-calorie” idea sounds plausible
Celery is mostly water and contains very few calories, so it makes a light snack. That can be useful if it replaces a more energy-dense food: a bowl of celery generally delivers less energy than a bowl of chips. But low-calorie is not the same as calorie-free, and digestion does not reverse that distinction.
The same reasoning applies to other foods sometimes labeled “negative calorie.” A food may be bulky, watery, or fibrous and still provide more energy than the body uses to digest it. Celery can fit into a satisfying eating pattern, but it is not a loophole that lets a person eat calories away.
