I’m hearing more and more these days about the “negative calorie” theory. So let’s dig into it a little—here’s what it is and why the theory behind it isn’t necessarily based in reality.
Here are some of the foods that are claimed to be “negative calorie-effect” foods:
*I found these recommended on a Dr. Oz site...of course.
And there are more...but this idea of “negative calories” is an interesting concept—the lists of benefits associated with these foods are well documented, but NEGATIVE calories?
Let’s go back to biology class. When we eat only a portion of the calories we consume are actually available for energy utilization by our bodies through the following processes:
Thermic Effect: The process that results in an increased metabolic rate as a result of the calories burned during the digestion and nutrient storage process. Larger meals have a slightly higher thermic effect, which is why you might feel your body temperature rise at Thanksgiving, giving you the “mat sweats”. This effect is responsible for about 10% of all calories consumed.
Excretion of non-digestible foods: This ‘excretion” is the total calories subtracted from the “usable” calories your body needs. This includes water, fiber, cellulose, resistant starch or other low energy bulk ingredients (artificial sweeteners/coloring). This process can be responsible for a varied number of calories based on the content of the consumed food.
The “negative calorie” hypothesis essentially comes from the processes above and is derived by the assumption that the implementation of these processes produce more burn of calories than the food itself contains. Some weight loss diets emphasize these foods, saying it creates a deficit of calories.
NOT SO FAST.
You know the saying...if it sounds too good to be true, it probably is. Of the little evidence available on the topic, there is not a lot of data in support of the “negative calorie theory”.
Yes, celery is long considered to have a negative yield in calories. But one small trial of this hypothesis found that of the 16 calories provided by the celery, only 2.24 calories were absorbed. Another study compared a “negative calorie diet” versus a traditional “low calorie diet”. The “negative calorie” diet included macros of 15% protein, 75% carbs (most “negative calorie foods” are veggie/carb based), and 10% fat. The “low calorie” diet contained macros of 15% protein, 55% carbs, and 30% fats.
There was no significant difference in results between the two groups. Authors concluded that the “concept of negative-calorie food has no external meaning or application, and contrary to expectations, both weight-loss diets were equally efficacious.”
So before you get all pumped up to eat that stalk of celery, there’s no magic trick to weightloss. There’s no evidence that supports a “negative calorie” food. BUT...BUT! There is a benefit to eating these foods—they’re full of high-nutrient, fiber rich, low calorie foods that will keep the body satiated and fueled all day long, creating a diet rife with opportunity for weight loss.
Just remember what I always see...eat like an adultand exercise at a frequency/intensity necessary for your goal. It’s tried and true!