These 7 Foods Can Burn More Kilojoules Than They Contain

Looking for a guilt-free snack? You can munch on these negative kilojoule foods to your heart's content.

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Ahh, the things we would eat if kilojoules didn’t exist. Don’t get us wrong, here at Sporteluxe we’re firmly against obsessively kilojoule counting. But I think we can all agree that we would indulge in Nutella cronuts a little more often if it weren’t for the undeniable fact that eating more kilojoules than you burn leads to weight gain. But what if eating certain foods could actually burn kilojoules? Yep, it all sounds a bit too good to be true, but welcome to the mysterious world of negative kilojoule foods.

Put simply, a negative kilojoule food is a food that requires more energy to be digested than it contains. This is called the thermic effect or specific dynamic action: the kilojoule cost of digesting the food is greater than the food energy content. If your daily kilojoule intake is like your bank balance, then eating negative foods is like going shopping on your work lunch break. If you’re earning more per hour than you spend, it doesn’t count, right?

negative calorie foods, zero kilojoule foods
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So, what are these miracle foods and is eating them the key to a hot, toned bod? Well, according to Nutritionist and Sporteluxe LA Editor Michelle Pelizzon, not exactly.

Yes, negative kilojoule foods may cause your body to burn enough kilojoules through digestion to offset their kilojoule intake (depending on the person). However, that kilojoule count would have likely been so negligible anyways that eating these foods won’t make or break your diet. The good things about these foods is that they’re usually fresh foods like celery or watermelon. They tend to have a ton of fibre which helps tame inflammation and encourages healthy digestion.

-Michelle Pelizzon

So basically, yes: we should be eating negative kilojoule foods. But not because they’ll burn kilojoules, as that won’t necessarily be the case for everyone. The reason we should eat them is because they give you a lot of bang for your buck. They give you a hefty dose of fibre and nutrients while adding basically nothing to your kilojoule intake. Here are some of our top picks:

1. Grapefruit

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Yep, there’s a reason this bitter fruit had a whole diet based around it in the 1980s. While we’re not suggesting you live solely off grapefruit, it’s a great addition to any healthy eating plan. It doesn’t technically have zero kilojoules but it does contain naringenin, an antioxidant with triggers the liver to break down fat. It’s also a fantastic source of fibre and is loaded with plenty of vitamins and minerals that help boost your metabolism and immune system.

2. Celery

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They say too much of anything is a bad thing. But if there’s one food you can eat endless amounts off and never feel guilty, it’s definitely celery. About 75% of a celery stick is actually water,  while the other 25% is fibre and other roughage. So, while the kilojoule-burning properties of celery will vary from person to person, it’s safe to say it’s a zero-kilojoule snack. It can also keep you full for a while, thanks to its high fibre and water content.

3. Cayenne pepper

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Seriously, is there anything cayenne can’t do? Not only does it work wonders for inflammation and help relieve headaches, it revs up your metabolism like nothing else. While eating the spice alone isn’t going to give you a six pack (it’ll just give you a very dry mouth!) it’s an awesome way to season your food. Not only does it add a spicy kick to your meals, it’ll send the fat-burning properties of whatever you’re eating through the roof. You can also start your day with some cayenne pepper mixed with hot water and lemon to kickstart your metabolism.

4. Watermelon

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What’s not to love about watermelon? Not only is it the perfect poolside snack on summer days, it’s nearly kilojoule-free! Each bite of watermelon contains about 92% water and 6% natural sugar. Hardly surprising, considering the fruit literally has water in its name! The extremely high water content will keep you hydrated and full long after you finish your slice. The fruit is also extremely high in lycopene, an antioxidant with powerful anti-inflammatory properties that has been linked to improved heart and bone health.

5. Leafy greens

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Leafy greens like spinach or arugula are as close to negative kilojoule as you can get. With less than 20 kj per cup, you could literally munch them all day every day and never gain weight. In fact, you would probably burn more kilojoules eating them than would you consume! But that’s not the best thing about getting your greens. From boosting your fibre levels to giving you a healthy dose of magnesium, folic acid and potassium, the health benefits are countless.

6. Cauliflower

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Whether you roast it, steam it or use it to make pizza, cauliflower is the perfect guilt-free base for any dish. Because the cruciferous veggie is so low in kilojoules, it would technically be possible to burn through the energy through the digestive process. It’s also one of the best anti-inflammatory superfoods out there and is very high in fibre and vitamin C.

7. Black coffee

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Yes, black coffee isn’t technically a food. But a cup of plain, black coffee contains zero kilojoules. The beverage has been proven to stimulate the burning of fat for energy, making it a perfect pre-workout drink for the gym. However, as soon as you add in milk, sugar and syrup, the kilojoule count of your cup of joe creeps up significantly. Also make sure you cap your coffee intake at 2 to 3 per day (and try not to drink it after 2pm), as too much can fry your adrenals and put your heart under strain.

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Emma Norris
A true believer in balance, Emma is just as passionate about pizza as she is about pull-ups. When she’s not writing, she loves strength training, visiting new cafes and trying out new fitness classes. Having lived in Ireland and Canada, Emma was bitten by the travel bug at a young age. She loves nothing more than visiting new destinations and experiencing different cultures. Emma grew up (and currently lives) near the beautiful Coogee Beach and is happiest when she’s near a body of water. She started her career in magazines and has recently made the exciting transition to the digital world.