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Do Negative-Calorie Foods Exist? Here’s What The Studies Say

Do Negative-Calorie Foods Exist? Here’s What The Studies Say
Evangeline Howarth
Writer and expert4 years ago
View Evangeline Howarth's profile

Feel bombarded by dieting myths? Well, we’re here to debunk at least one for you today — negative-calorie foods.

We’ve all heard of the idea that there are foods out there that take more calories to digest than they really contain, but is this really possible? According to a new study, it just doesn’t work like that.

Foods such as celery and cucumber have long been touted as negative-calorie foods, popular in the dieting community to keep calorie levels low enough to lose weight. While there’s no denying that these foods are pretty low in calories, here’s why there’s no such thing as negative-calorie foods.


What does “negative-calorie foods” mean?

A calorie is a unit of measurement for energy — the calories that you see on your food packaging is actually a kilocalorie (1,000 calories). The idea behind a negative-calorie food is that it contains less calories, or energy, than the energy it takes to digest and absorb the nutrients you get from it. That would mean that you end up in a calorie deficit from eating these foods.

While this theoretically makes sense, it’s sadly not how it works. Even foods really low in calories have enough calories that there’s energy left over from digesting and absorbing them, according to this study.1

The study

The research was carried out by a team from the University of Alabama on bearded dragons — a lizard that originates in Australia. The researchers chose to feed the bearded dragons celery as this is the food that tops the lists for being a supposed negative-calorie food.

They measured energy lost in faeces and urine, metabolic rate, and the cost of meal digestion. They found that the lizards still retained nearly a quarter of the energy they ingested from the celery meals. The study also didn’t include the energy cost of chewing which would reduce the amount of energy left over too.

The researchers believe that the results would be similar for humans eating celery would have equivalent energy retention, as the rise in metabolic rate after a meal is similar in lizards and humans.


Don’t lose hope yet

The researchers argue that although you might not use all the calories up in digesting, absorbing, and excreting the celery, your basal metabolic rate (the energy required to keep your body functioning at rest) means that the left over energy from eating celery would be used up. In fact, the average woman would need to eat 12.6kg of raw celery just to fuel these minimal metabolic needs.


Take Home Message

It seems like there’s still quite a lot to learn here, but the main point is that celery almost definitely isn’t a negative-calorie food. There’s no denying that it’s an incredibly light snack if that’s what you’re going for — and you’ll easily use the rest of the energy you get from it. There could be other foods out there that are though, so let the dieters dream on!

Enjoy this article on negative-calorie food?


Our articles should be used for informational and educational purposes only and are not intended to be taken as medical advice. If you're concerned, consult a health professional before taking dietary supplements or introducing any major changes to your diet.

1. Buddemeyer, K. M., Alexander, A. E., & Secor, S. M. (2019). Negative calorie foods: An empirical examination of what is fact or fiction. bioRxiv, 586958.

Evangeline Howarth
Writer and expert
View Evangeline Howarth's profile
Evangeline is a Veganuary convert and newbie vegan with a degree in English and French from the University of Nottingham. Having recently ditched the meat and dairy, she really enjoys the new flavours and cooking techniques she’s encountered on a plant-based diet. She’s been shocked by the millions of ways you can use tofu, however still hasn’t found a decent cheese substitute! When she’s not in the office or eating, Evangeline usually out running or sailing. As a qualified RYA Dinghy Instructor and a marathon runner, she knows the importance of providing your body with the right nutrients for endurance sports as well as a busy lifestyle. Find out more about Evie's experience here.