The ‘negative calorie diet’ sounds like a simple and straightforward concept. It means that you’re maintaining a negative calorie balance in order to lose weight?
Well yeah, sometimes. But other times, the writers involved are actually referring to ‘negative calorie foods’. These are foods that are so low in calories that they actually require more energy to chew and digest than they add to your overall count.
In other words, if something takes 5 calories to eat and only contains 3 calories, then it has a ‘net worth’ of -2 calories. That’s negative figures!
Do Negative Calorie Foods Really Work?
That’s the theory but unfortunately, this doesn’t necessarily add up the way it sounds. There is actually no evidence that any foods have a genuinely ‘negative’ impact on total calories consumed (1). So in other words, you can’t just eat 500 sticks of celery and burn through your fat!
Apart from anything else, even if these foods did burn calories, there are plenty of things you could do that would burn a lot more calories – such as practically any kind of movement! And there are more calories in things like celery than most of these overly-optimistic sources would have you believe. Celery for example actually contains 16 calories per 100 grams. That’s not tons but it’s still a fair few more than you’ll burn simply by chewing and digesting food! And grapefruit which is often quoted as ‘negative calorie’ actually contains 42 calories per 100 grams. That’s significant!
But that’s not to say that finding foods that have an almost negligible impact on calories is a complete waste of time. Actually, sticks of celery and bowls of grapefruit can be very useful when it comes to improving your overall intake for a number of reasons.
Most notably, eating these kinds of foods is a great way to satiate yourself for just a little while longer when you get hunger pangs. Hunger comes in waves, so if you find your stomach grumbling then giving something to keep it quiet is a great way to make it to the next meal. And in the grand scheme of things, 8 calories from a stick or two of celery isn’t going to break the calorie bank.
So with that said, let’s take a look at some of the foods that come pretty close to being negative calorie…
Celery
We’ve already talked about it a whole lot, so let’s start with celery! Celery is a great way to keep yourself feeling full without actually adding to your calorie total because it is actually 75% water! (Then again, so are we…). Better yet, the other 25% is just fiber and roughage which passes right through the body. This is pretty good for you and you’ll also get a few other nutrients such as vitamin C, vitamin A and vitamin K. It also has antioxidant properties. When you consider the low calorie count, this is an excellent return on investment and pretty much the opposite of an ‘empty calorie’.
Grapefruit
The other food we already mentioned is grapefruit. So why is this on the list? Again this is mostly water (60%) and also contains a lot of healthy nutrients. What’s particularly interesting about it though, is that it can help to boost the metabolism. Also, grapefruit contains a substance called ‘pectin’ which makes you feel fuller and protects against heart disease. All in all, it’s a pretty good combination!
Many people on strict diets will choose grapefruit as their breakfast meal thanks to these properties.
Lettuce and Leafy Greens
For lunch, how about some leafy greens? Leafy greens include things like cabbage, lettuce and rocket – and all of them are excellent at padding out a meal without padding out the calories.
Some are even better than others. For instance, kale is super high in vitamin K, with 100grams you get 1327% of your vitamin K requirement and a ton of anticarcinogens to boot. Spinach is also very good: it’s particularly thermogenic (meaning it burns a lot of calories to digest) and it is high in protein and ‘phytoecdysteroids’ which may support muscle growth!
Watermelon
Watermelon is again a little higher in calories than some things on this list but nevertheless is mostly water and fiber. It’s also high in B vitamins which actually aid the body in burning sugar for energy.
Cucumber
Add some slices of cucumber to salad and you’ll be adding barely any calories! Again, this is mostly water and fiber (the taste gives it away) but they’re also convenient, refreshing and great for adding to any sandwich.
Tea
Some kinds of tea – especially if you don’t add sugar – are actually zero calories. What’s more, a number of them can help to burn more fat and are high in nutrition! This means you can drink as much tea as you want and keep your total calorie intake right down. But while this is true, you should avoid drinking too much tea with caffeine in it as this can eventually make you jittery, nervous and restless.
The same is also true for black coffee. A little can boost your metabolism and energy levels while at the same time not adding any calories. But don’t rely on it or you’ll end up wired and tired!
Cold Water
Finally, there is one option that is actually negative calorie… cold water! If you drink cold water with ice in it, then your body will need to heat that back up to body temperature. This actually takes 10 calories to do… if you drink several glasses throughout the day. On its own, this would take years to burn a single pound of fat so it’s not going to change your life!
But 10 calories is better than a kick in the teeth. And water also has a ton of other good benefits for you. Most of us exist in a state of permanent dehydration which actually affects digestion, mood and more – and even causes headaches! To make sure that these aren’t problems for you, add some more cold water to your diet.
Chewing Gum
Okay, so this one is cheating and it’s not highly advisable.
However, seeing as you don’t actually swallow gum, you’re not adding any calories. And this could be good news seeing as chewing (mastication) burns roughly 11 calories per hour. Not tons, but it all adds up and if you chew gum for eight hours a day that’s… 80 calories burned. Do this for a working week and that’s 400!
But there are some serious caveats here. Firstly, chewing gum almost always contains sugar. This is bad for your teeth and it also means you actually will gain some calories from the gum. If you pick sugar free gum then things don’t get much better, seeing as you’re actually tricking the body into thinking it is getting sugar. This causes an insulin spike in the blood which in turn uses up any available glucose, stores it as fat and then makes you hungry!
And as though this wasn’t bad enough, chewing gum also causes the stomach to prepare itself for food. This results in the release of stomach acids which can end up burning the lining and causing all sorts of problems in the long term.
So, the take home message here? Gum is not the answer. Celery is the answer. But only as a way to tide you over until dinner!