Wouldn't it be great: chewing on a few sticks of crunchy celery and losing weight at the same time. It's a theory enticing enough for us to fill our fridge with these 'negative-calorie' foods and say goodbye to our favourite meals.
But what are these so-called negative-calorie foods -- and can they really help us lose weight?
"The concept of 'negative-calorie' food refers to foods that supposedly take more energy to digest and process in the body than they provide in calories. Or to put more simply, the idea that you burn more calories digesting and metabolising certain foods than the foods themselves contain," Robbie Clark, dietitian and sports nutritionist, told The Huffington Post Australia.
"The theory is that by consuming these 'negative-calorie' foods, you can lose weight."
The types of foods often credited as negative-calorie are usually high in water content and fibre, including:
- Spicy foods
- Foods that contain caffeine
"Cold foods, including cold water, are sometimes called 'negative-calorie' foods because your body burns extra calories warming them up during the digestion process."
Unfortunately, it's not that easy. Eating a few carrots or drinking iced water is not going to make weight magically slip off.
"There is no real validity to the theory that negative calorie foods can be a weight loss aid, and in actuality there are no negative calorie foods and can be seen as a diet myth," Clark said.
"Even though some foods may give your metabolism more of a boost than others -- and some contribute very little calories to begin with and do require a couple of extra calories for digestion -- the extra calories burned won't be enough to affect your weight."
A healthier approach to eating is to avoid all fad diets, adopt a healthy relationship with food and eat a balanced, nutritious diet while listening to your body's hunger cues and not overeat.
Instead of seeing these foods as a quick fix, Clark recommends to include them in your daily meals and snacks which, when eaten regularly, can help maintain a healthy weight.
"Many of these foods are vegetables and fruits which should be part of any healthy diet," Clark told HuffPost Australia.
"They are high in fibre (which is very important to gut health), high in water content (which keeps the body hydrated) and contain vitamins, minerals and antioxidants to help your body fight off inflammation, illness and disease. Therefore, these foods are beneficial to consume but should be seen for their health benefits rather than being 'negative-calorie' foods."
In fact, fixating on 'negative-calorie' foods carries a risk of developing a negative and restrictive attitude towards food.
"By labelling certain foods as such -- and following extreme diets that promote eating only a few foods -- it can cause you to miss out on important nutrients obtained from other food groups and form an unhealthy relationship with food," Clark said.
"It can also make social outings around food restrictive and awkward."
Focus instead on having a balanced diet, including lots of whole foods and treating yourself every now and again, too.
"A healthier approach to eating is to avoid all fad diets, adopt a healthy relationship with food and eat a balanced, nutritious diet while listening to your body's hunger cues and not overeat," Clark told HuffPost Australia.
"This should also be coupled with keeping your body well hydrated by drinking water, incorporating regular exercise and getting enough quality sleep."