the claim that certain foods (like celery and lettuce) contain so few calories that you expend more energy chewing and digesting them than they actually provide. Anahad O’Connor of The New York Times contends this claim is based on inexact science:Most people probably haven’t heard of “negative calorie” diets,
Topping the list of “negative calorie” foods are vegetables like cabbage, lettuce, cucumbers and celery. Celery, for example, contains 8 to 10 calories a stalk and is 95 percent water.Check out the video that accompanies the report: Are Negative Calories for Real?
Chewing most foods typically only burns about five calories an hour, but the act of digesting may require slightly more. That is particularly the case with celery because it is mostly cellulose, a type of fiber that humans do not have the enzymes necessary to properly break down and use.
Cathy Nonas, director of obesity and diabetes programs at North General Hospital in Harlem, said that while no hard studies exist, it is possible that snacking on celery might cause a very slight calorie deficit. But the difference would be so minuscule that at the end of the day it would have no real impact unless the celery was replacing other fattening or high calorie foods. The other problem is that celery is not only low in calories, but also low in vitamins and minerals.