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Negative Calorie Diet
I keep hearing about negative calorie foods such as celery. Can foods really have negative calories? Is there any truth to this claim?
When marketers say a food has negative calories, they are claiming that the body burns more calories digesting the food than it actually contains.
There is no scientific proof that certain foods utilize more calories than they contain. To my knowledge, the calculations used to determine these claims have not been obtained through reliable research methods and have not been published in peer-reviewed journals. The lack of research in this area is probably due to the fact that research takes time and money. Researchers only tend to pursue hypotheses that are worthwhile and, given the unlikelihood that the negative calorie theory is correct, researchers are not willing to spend their resources on this claim.
From a physiological standpoint, our bodies are extremely efficient at using the calories contained in food. Thank goodness for this incredible efficiency or we, as a species, might not be here today!
Since the number of calories in question is extremely small, we should touch on the impact that the negative calorie theory would have on weight loss – even if it were true. In a nutshell, the impact would be insignificant. For example, let's say that instead of a stalk of celery providing 10 calories, it actually burned 10 calories – a 100% reversal, which is extremely unlikely! Even so, you would have to eat 350 stalks of celery to lose 1 lb. I don't call that eating for health, eating for enjoyment or eating to lose weight – I call that crazy! It is much more effective to manipulate calorie deficits by adjusting total calories ingested and total calories burned through exercise.
Having said that, most of the foods that I have seen listed on "negative calorie food" lists are actually quite healthy, nutrient rich and filled with fiber (e.g., celery, carrots, lettuce, broccoli, onions, and cabbage.). Therefore, eating these types of foods is highly encouraged. However, incorporate them into your diet in a balanced and reasonable way. Remember, a healthy diet should be nutrient rich, balanced, enjoyable and sustainable over a lifetime.
It's in our nature to seek out that magical pill or miracle diet to make it all so easy. However, I hope that this column revealed the unlikely nature that these claims have any validity or significance to actual weight loss or maintenance. If people have been successful using this "negative calorie" diet, it is most likely due to decreasing their total caloric input by replacing high calorie foods with low calorie foods and increasing satiety by eating low-energy dense foods.
Our expert, Dr. Sharon E. Griffin, holds a B.S., M.S., and Ph.D. in the areas of exercise science/physiology. She also holds a second M.S. degree in Nutrition and is a licensed nutritionist and an ACSM certified health and fitness instructor.