Negative-calorie foods are the Holy Grails for dieters. But do they really exist?
A negative-calorie food is one that has fewer units of energy than it takes to consume it—in other words, you burn more calories eating the food than the food has itself. Although many believe that chewing uses up a lot of energy, it actually burns about as many calories as watching grass grow. The real energy expended is in the digestion of the food. A calorie is a measure of energy content. Of course, every food has some kind energy (calorie) content; however, there are foods whose caloric energy cannot be released into our systems because our bodies cannot break them down. Our bodies also burn more energy just trying to digest these substances.
Here is where celery comes in.
An 8-inch stalk of celery only contains about 6 calories; even better, celery contains cellulose, which happens to be one of the substances our bodies can’t break down. Because of its composition, our bodies expend more energy trying to digest a piece of celery than it actually contains.
However, don’t think a steady diet of celery is going to make the pounds drop off. All of the energy burned by eating a bunch of celery would come to no more than a few dozen calories per day. Since you have to burn 3,500 calories to drop one pound, those handful of calories would be just a drop in the ocean. But it is a start!