Do Calorie-Negative Foods Really Exist? Dietitians Weigh In
We hear a lot of crazy food stories here at Delish, but the concept of “calorie-negative foods” might just be the wildest. Premised on the notion that chomping certain foods can result in burning more calories than the foods contain, this legend would have you believe that a lettuce salad topped with sliced cucumber and celery equals a calorie-free (albeit incredibly boring!) lunch.
But do calorie-negative foods actually exist? The idea might seem to (kinda) make sense, but is there any evidence to back it up? I did the research, combing through scientific studies and consulting two dietitians to get their qualified opinions. Here’s everything you need to know about "calorie-negative" foods: what they are and whether or not you really need to be buying that third bag of celery:
What Are “Calorie Negative” Foods?
So-called “calorie-negative” foods contain very few calories to begin with. Katherine Hottel, RD, shares that they’re usually “nutrient-rich with a high water and fiber content.” Popular examples include celery (the most popular one!) as well as cucumber, grapefruit, and lettuce. According to dietitian, health coach, and author Jessica Cording, MS, RD, these foods are called negative-calorie foods because they’re thought to “contain fewer calories per serving than it takes to eat, digest, and metabolize” them. But this isn’t necessarily true.
“There really is not sufficient data to support that there really is such a thing as a negative calorie food, Cording says. Hottel agrees, saying, “The idea that foods could subtract calories from the body is a fantasy.”
But why not? If a stick of celery only contains six calories, how are we NOT burning that energy off (and more!) as we digest it? To understand this more fully, let’s take a look at how our bodies are actually burning those calories.
How Our Bodies Actually Burn Calories
Our bodies expend energy—burn calories—in a few different ways, including, according to Hottel, “basic survival systems, activities of daily life, movement, and the process of breaking down and digesting food.” That last category only equates to about five percent of the total calories we burn: an incredibly small portion. Given that, it’s just not plausible to think that the small bit of extra effort it takes for our bodies to chomp through a stick of celery will have that big of an effect on our total calorie expenditure. Still not convinced? Let’s look at the evidence of the lizards:
Examine The Lizard
In 2019, a group of scientists conducted a study with lizards who were fed only celery for a number of days. The scientists carefully measured the number of calories the lizards ingested through the celery, as well as how much energy they spent. In the end, they found that the lizards released “on average 29% and 14% of meal energy” through their “feces and urate” (essentially poop and pee). They also spent an additional 33% of that energy through their basal metabolic rate (basic body function); this left the lizards with “a net gain of 24%” of the energy they had ingested. In other words, eating celery didn’t result in negative calorie expenditure for lizards. So why would we expect it to be different for us?
Is There Any Benefit To "Calorie-Negative Foods"?
While negative-calorie foods aren’t really a thing, there are still a lot of great reasons to continue eating them! According to Cording, many of these foods are “high in important nutrients like fiber, vitamins, minerals, and antioxidants,” all of which are good for our bodies. If you do happen to be trying to lose weight, she also shares that extra fiber is “a great way to help you feel satisfied.”
Also—and this is coming from a dedicated celery fan—they’re also absolutely delicious. After all, what would summer be without a smacked cucumber salad? What would a platter of buffalo wings be without the celery sticks? There are so many reasons to eat these foods that have nothing to do with the amount of calories they bring to our bodies, so turn around and wheel that shopping cart back into the produce aisle!
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