Does chewing celery consume more calories than it provides?
A friend of mine told me that if I wanted a low calorie snack, I should eat celery because it actually has negative calories. He claimed this meant that I would burn more calories chewing and digesting the celery than I would actually get from it. Is what he claims true? Are there any other negative-calorie foods? Oh, and you wouldn't happen to know a good low calorie dip for the celery, would you?
Cecil has been hearing this for years, and for just as long has been disinclined to believe it. Nosing about on the Web, however, I started to wonder. As you might expect, you find quite a few hucksters touting the benefits of alleged "negative calorie" foods, including not just celery but asparagus, broccoli, lettuce, grapefruit, and a long list of other fruits and vegetables - and for a small fee these helpful folks will reveal to you their foolproof fat-burning diet plans. More scientifically minded parties dismiss these schemes, but tend to do so in such sniffy terms that one suspects they haven't really considered the question of negative-calorie foods on its merits. Moreover, one usually reliable source, the Urban Legends Reference Pages at www.snopes.com, says that while the negative-calorie shtick on the whole is a crock, what you've heard about celery is true. However, no corroboration of this statement is supplied.
Our mission therefore was clear: Time to conduct another experiment in the Straight Dope Kitchen of Science.
We went to the supermarket and bought a bunch, cluster, mess, or whatever-you-call-it of celery packaged by A. Duda & Sons in Salinas, California. Having returned home and trimmed off the unpalatable parts, we weighed the remainder one stalk at a time on our Cuisinart precision portion scale - 757 grams total. (The scale lets you figure it in ounces too, but we're great believers in the metric system, and besides, "grams" will look classier when our report is published in the New England Journal of Medicine.) Further research revealed that celery contains about 14 kilocalories (what you layfolk call just plain "calories") per 100 grams, so we were looking at 106 calories' worth of the vegetable.
We then commenced a rigorous regimen of celery consumption. This was tougher than you might think - you don't lay into a plateful of celery with the same enthusiasm you might have for an equivalent quantity of barbecued ribs. After an hour I'd eaten eight stalks. (I was interrupted a couple times, thankfully.) All things considered, I think I packed away as much of the stringy stuff as could reasonably be expected. Total consumption: 514 grams. Total calories ingested: 72.
There's no easy way to determine how much more energy you expend chewing and digesting celery than you would if you were just sitting there. However, it's fair to say that when eating celery, you're using more energy than you're taking in. Bear in mind that you burn roughly 60 calories per hour while asleep, 85 while eating, and - I think this is interesting - 130 while doing "computer work." (I was tapping away at the keyboard while munching my celery; obviously whoever figured these things out understands the intense concentration required to produce this column.) According to one calorie calculator I found, I need 78 calories per hour just to support my body weight. The unavoidable conclusion? If I did nothing but eat celery and write the Straight Dope all day, I'd waste away to a twig.
Does that mean there's something to this negative-calorie business? Yes and no. Some advocates expound a vague and fanciful theory that neg-cal foods ramp up your metabolism by stimulating surplus production of some sort of enzyme, the idea apparently being that you'll blast calories into the void like a Bessemer converter. This is clearly nonsense. If it were that easy, everyone would be thin already. On the other hand, the calorie content of many vegetables is pretty low. Chinese cabbage, cucumber, and lettuce are all about the same as celery; asparagus has 20 to 23 calories per 100 grams, depending on who's counting, carrots 25 to 43, broccoli 26 to 34. By contrast, even 95 percent lean hamburger has at least 170. Except at the bottom of the range you won't have a net loss of calories while eating vegetables, but you won't gain much either. On the other hand, if you start loading up your celery with peanut butter or French onion dip - even no-fat dips run about 25 calories per two-tablespoon serving (oops, 30-milliliter serving), which where I come from might get you through one stalk - sorry, pal, all bets are off.