There’s Fiction, and Then There’s Fact
Clearly, I’m no nutritionist. So I enlisted Ramos, who helped me make sense of all the seemingly conflicting information.
The Fiction: Negative-calorie foods not only are very low in calories but also have a unique, powerful makeup that puts our bodies in superburn mode—powering through foods so quickly that we lose weight simply by eating.
The Fact: Eating and digesting food do create a slight spike in our metabolism, but it doesn’t add up to much—actually, less than 30 percent of the calories our bodies burn at any given time, says Ramos. Though celery, the poster child of negative-calorie foods, does contain a mere six calories, we expend only about half a calorie to digest it, according to Global Metabolism Myths, by Mitt Hickey. Guess that negative-calorie math doesn’t exactly measure up when we get specific. Bummer.
The Fiction: There are so few calories in negative-calorie foods that just chewing and swallowing them burns up more than the calories they contain (plus that cookie you ate a few minutes ago).
The Fact: Chewing, according to the popular diet website HungryGirl.com, burns about eleven calories an hour. Sticking with the celery example, it probably takes about five minutes to chew a piece of celery (and that’s for a slow, slow eater). I was no math major, but even I can do the simple division that shows you’d have to chomp for longer than that to actually chew away the calories.
Although chewing up celery sticks may seem strenuous, it’s probably not going to leave us burning enough calories to make any real difference. Even to lose just one pound, we’ve got to burn off 3,500 calories. The idea that a certain food will act as a magic pill that helps us burn off other foods is just not true—celery or no celery. “Classifying foods as negative calorie is misleading,” says Ramos. “All food has energy, and therefore calories. And we need calories.”
The verdict? What we can take away from those negative-calorie food lists is the power of fruits and veggies. Studies find consistently that people who eat diets high in them lose weight—probably not because these foods act like diet pills in our systems, but because they help us stay satisfied with fiber and nutrients so we don’t crave the junk food that leaves us craving more junk. Negative calorie or not, regularly including these foods in our diet will keep us not only at a healthy weight, but just plain healthy.
Updated December 1, 2010
