Celery: A negative calorie food?
5PH/Shutterstock
Diets are everywhere, but could eating “negative calorie” foods, such as celery and grapefruit, help to boost weight loss?
A calorie is a unit of energy, usually expressed as kilocalories (kcal) for the energy content in food. The theory behind negative calorie foods is that some foods have lower calorie (energy) content than the amount of energy it takes to digest and absorb the food into the body. This sounds plausible, in theory. But in reality, even the lowest calorie foods, such as celery, contain more calories than it takes to break down and absorb them in the body.
Our energy needs are made up of three components:
• The energy needed to maintain a body at rest, which is the energy needed for our body to carry out its basic processes so we can live.
• The thermic effect of eating, which is the increase in metabolic rate after eating, while food is digested and absorbed.
• Additional energy needed for activity and exercise.
Of these, the thermic effect uses the fewest calories—about 10% of the energy we take in. In other words, about a tenth of the calories we eat are used to process our food—this includes chewing our food, moving it through the digestive system, absorbing nutrients, and storing excess energy.
Foods such as celery, grapefruit, broccoli, tomatoes, and cucumber have all been touted as negative calorie foods, but there is no scientific evidence to support this idea. Although they are very low calorie foods, with seven to 30 kcal per 100g, it still takes less energy than this to process them. This is because they contain large amounts of water and fiber, which have a very low energy cost.
Replace, don’t add
These foods are very useful for people who are trying to lose weight, as they contain a low number of calories. By replacing the food in your diet with some of these—for example, replacing a side portion of chips with a side salad—it is possible to lower your calorie intake considerably. As an extra boost, they are full of nutrients, such as vitamins and minerals, and also contain a lot of fiber, which also has many benefits for your health.
Healthier options should replace higher calorie foods in a meal, not just be added to it.
LightField Studios/Shutterstock
It’s important to replace higher calorie items on a plate rather than add these fruit and vegetables to meals, as by simply adding healthy items you increase the overall calorie content. For example, a cheeseburger plus a salad contains more calories than a cheeseburger alone.
In order to lose weight, people need to use up more energy than the energy (calories) they eat and drink, but this is difficult. Research has shown that people tend to underestimate the calorie content of the food they consume, and they underestimate it by more if they are obese rather than normal weight.
Researchers have also shown that when people visit fast food chains with a healthier image, they underestimate the calorie content of their meals compared with the same meals at a restaurant with a less healthy image, and may end up consuming more calories overall.
Another difficulty is keeping weight off in the long run. Many studies have shown the short-term benefits of diets to help with weight loss, but over 80% of people put the weight back on again over time. In many modern societies, there is easy access to cheap high-calorie foods, so it is difficult to resist high fat/sugar options on a permanent basis.
Unfortunately, negative calorie foods are a myth, and there is no easy way to lose weight and keep it off in the long run. Changing your food and drink options for healthier ones on a permanent basis is more likely to lead to sustained long-term weight loss than short-term dieting alone.
Want more news like this?
Sign up to receive our email newsletter and never miss an update!
By submitting above, you agree to our privacy policy.
Louise Dunford is the Director of the Institute of Allied Health Sciences Research at De Montfort University. This article was originally featured on The Conversation.
Want more news like this?
Sign up to receive our weekly email newsletter and never miss an update!
By submitting above, you agree to
Latest Content
You can appeal when your social media content gets taken down, but you need to know where to look.
By Stan Horaczek posted Jul 20th, 2018
If you think your social media post shouldn't have been removed, you have options.
popsci shop
Get world-class sound and 16 hours of battery life.
By Stack Commerce posted Aug 15th, 2018
Get world-class sound and 16 hours of battery life with these noise-cancelling Bluetooth headphones that are now just $75.
And you thought this summer was hot
By Charles Choi posted Aug 15th, 2018
For the first time, astronomers have detected iron and titanium vapors in a planet's sky—the metals glowing hot like the filaments in a light bulb in the searing…
Sizzlin' savings.
By Billy Cadden posted Aug 15th, 2018
PopSci is always on the lookout for today's best deals. Our lists will be updated throughout the day, so check back to see if stumbled upon any awesome new discounts.
Our editors scrounged up some truly bizarre facts.
What’s the weirdest thing you learned this week? Well, whatever it is, we promise you’ll have an even weirder answer if you listen to PopSci’s newest podcast.
Playing the most popular game in the world on Samsung's new Flagship phone.
By Stan Horaczek posted Aug 15th, 2018
Gaming phones are increasing in popularity so get your thumbs ready.
5 questions answered.
Karl Havens/The Conversation posted Aug 15th, 2018
One of the longest-lasting red tide outbreaks in the state’s history is affecting more than 100 miles of beaches. Meanwhile, discharges of polluted fresh water from Lake…
2018 has been pretty overwhelming. Do what you can to make your friends feel comforted.
By Mallory Johns posted Aug 15th, 2018
They work 60 hours a week, have half a dozen side-hustles, and never, ever cancel plans. These gifts will appeal to all five of their senses, and will hopefully help…