Despite what Doctor Who suggests, it does't just grow legs and walk away.

It actually disappears into thin air!

Hey guys. Julia here for DNews.

New year brings new resolutions.

For many, that means getting back to the gym.

"Feel the burn!" seems to be the rallying cry for exercise enthusiasts everywhere.

And how many magazines have flashy covers like "10 new ways to burn fat in the new year"!

And what does that even mean? How can you "burn fat" and where does it go?

When you eat too much protein or carbs, your body converts it and stores it as fat.

To get your body to "burn" up these cells, your body has to use up the immediate energy from food, and dip into your energy reserves.

In other words, you burn more calories than you take in, so you have to use your fat stores.

And that adipose tissue or fat is made up fat cells called adipocytes filled with molecules called triglycerides.

When you're trying to "burn fat", you're really trying to get rid of these triglycerides.

High levels of which are linked with heart disease and metabolic syndrome.

Triglycerides are made up of glycerol and three fatty acids.

In order to burn fat, you have to oxidize these molecules.

Now the complete oxidation of a single triglyceride involves many biochemical processes and enzymes.

But the process can be boiled down to a single chemical equation.

Now this may look complicated but what's basically happening here is that when you're exercising, you're tapping into your fat stores.

So you are "oxidizing" or breaking down that molecule to release carbon dioxide, water, and energy.

I bet you're imagining that most of that fat gets turned into energy like your gym teacher or personal trainer tells you.

Well, they'd be wrong.

According to a study published in the British Medical Journal, most of the fat turns into carbon dioxide and water.

According to their calculations, 84% of an adipose triglyceride is given off as CO2.

So for example, if you lose 10 kg of fat, 8.4 kg is exhaled as CO2.

As the lead author says, when someone burns fat, "most of the mass is breathed out as carbon dioxide. It goes into thin air"

The rest is given off as water in some way or another, like in urine, sweat, tears or other bodily fluids.

The authors also calculated about how much carbon dioxide we give off in an average day.

Even without hitting the treadmill, with every breath we take, we give off 33 grams of carbon dioxide. Woohoo!

But before you get too excited about losing all that CO2 and burning all that fat, the authors also note that a single muffin contains 20% of your daily intake of energy.

A single, lousy, muffin.

So a small amount of food can quickly make all that exercise for naught.

But if you do want to get more bang for your breath, you can actually measure how much fat you're burning by measuring your breath.

So if you want to stick to that new year's resolution, take a deep breath, hit the gym and feel the burn.

Losing weight in the future will be weird.

Not only will your breath keep track of how much fat you're burning, but an algorithm will decide what you should be eating!

To find out more about that, check out this episode right here.

Microbians are the ecosystems living in all of us. Each of us carry around millions of micros in our guts.

And other studies like one published in the journal Science found that guts bacteria could be the crucial factor in a person's metabolism.

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