Not quite. A medium-size stalk of celery contains roughly six calories, and you'll burn less than one of those digesting it. "Eating does burn calories," says Toby Smithson, a registered dietitian and a spokesperson for the Academy of Nutrition and Dietetics, but that only works out to about 8 percent of caloric content on average. (Fatty foods require fewer calories to digest, while protein-rich items require more.) In other words, your digestive system needs roughly 32 calories to process that 400-calorie ham-and-cheese sandwich you had for lunch.
You might think that chewing uses up a lot of celery's calories, but that's not the case either. According to Smithson, chewing only expends about five calories per hour—not a very effective method of exercise.
That said, it's pretty much impossible to get fat eating celery. Compared to most of what we eat, celery and other water-rich, low-calorie foods like cabbage, lettuce, and cucumbers have a negligible impact on calorie intake. However, celery does have some nutritional benefits: It's an excellent source of vitamin K and a pretty good source of vitamin A, folate, and potassium. Not what you wanted to hear, we know.