Many a dieter's dream is to discover a secret treasure trove of calorie-free foods that you can be eaten with complete impunity. One popular diet tells you that certain foods contain "negative" calories -- and that the more you eat of them, the more fat you burn. The negative calorie diet may make sense, in theory; however, medical experts chalk it up to wishful thinking.
The Claims
The operating theory behind negative calorie foods is that it takes more energy for you to chew and digest them than the food provides in actual calorie intake. A typical example of a negative calorie food is celery. Weighing in at a light five to 10 calories a stalk, celery is 95 percent water, according to a July 2006 New York Times article. Gnawing on celery burns around 5 calories an hour, but digesting it takes more, as celery contains a type of fiber that's difficult for your body to break down, the article goes on to say. The negative calorie food diet assumes that when you eat certain foods, you end up with a net loss of calories. In short: The more you eat, the more calories -- and fat -- you burn.
The Foods
Topping the list of negative calorie foods is celery and other green vegetables, namely asparagus, cabbage, lettuce, cucumbers, broccoli, cauliflower and zucchini. However, depending on which Internet website you visit, other low-calorie fruits and vegetables get a mention, including berries, grapefruit and other citrus fruits, melons and root vegetables such as beets, carrots, turnips and radishes. According to EveryDiet, advocates of negative calorie foods claim that eating a five-calorie stalk of celery burns 95 calories.
The Reality
The negative calorie food diet works only in theory, says MayoClinic.com preventive medicine specialist, Donald Hensrud, who goes on to note that 10 percent of your energy is expended on digesting food each day. So low-calorie foods such as celery and broccoli may take more energy for your body to process. However, there are no scientific studies to prove that this results in weight loss. Director of obesity and diabetes programs at North General Hospital in Harlem, New York Cathy Nonas told the Times that the negligible net calorie deficit has no impact on weight loss unless the so-called "negative calorie" fruits and vegetables you choose to snack on are eaten in lieu of calorie-laden foods.
Other Insight
The Weight Control Information Network, or WIN, takes a more no-nonsense approach when it comes to foods like cabbage and grapefruit, which purportedly have magical fat-burning properties. No food can alter your metabolism and make you burn more fat, says WIN. The caffeine in coffee and tea can boost your metabolism slightly, but even these foods won't result in long-term weight loss.
Healthier Dieting
Low-calorie, negative calorie foods -- especially fruits and vegetables, which are high in fiber -- are a healthy addition to your diet, says Hensrud. However, diets that limit your food choices are difficult to maintain in the long run and may cause nutritional deficits. Weight loss on a negative calorie food diet is most likely the result of your consuming fewer calories than you normally would, says EveryDiet. If you want to lose weight permanently, your best plan of action is to cut down on the number of calories you consume each day and get regular exercise, says WIN.
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