The world seemingly is obsessed by losing weight, shedding those few extra pounds, and getting lean. We all know that, to put it super simply, if you exercise and eat well, you lose fat.
But where does fat go? How does it physically leave your body?
It’s a common misconception that your body turns it into energy. A lot of people also think your body transforms fat into muscle, which is simply impossible, sadly – although would be great.
So if not any of these, where does it actually go?
Fat, in whatever form, is known as a triglyceride which can be converted into glycerol and fatty acids. These are used to give you energy to live (like a fuel source for your body) or stored as fat tissue.
This is why excessive calorie consumption and a sedentary lifestyle result in fat gain. If you eat a little less and move a little more, the hormone lipase (which lives in your pancreas) breaks down the fat stores.
Your fat stores are a collection of fat cells. These develop typically during childhood and puberty, and they don’t really ever increase in number after this.
The cells themselves expand when the digestive system stores fat for later use. They then shrink when your body uses this fat — think of fat as a battery for back-up energy, in case you skip a meal, or get lost in the woods for days or something. It’s a survival technique.
So where does fat go?
So your body burns fat in a chemical reaction. A byproduct of this metabolic reaction is excess CO2 and water (and a few other things, but let’s not go into that today…)
So fat becomes mostly carbon dioxide and a little water. You breathe out the CO2, and the water just joins in with the rest of your body and is expelled eventually as sweat or urine.
In short, you pretty much just exhale fat.
Surprised? Understandable, but basically everything we eat (give or take) can be exhaled as CO2. Anything you consume which is a carbohydrate can be turned into carbon dioxide and water – this goes from bread to alcohol. This even happens for protein, except some parts also convert into urea.
So then, if fat turns into carbon dioxide, why can’t we just breathe and lose weight? If only… Sadly that’s not how it works.
Energy: A Mystery
It’s commonly assumed that energy in=energy out, and that the best way to lose or maintain weight is to track this. However energy as a concept is pretty tricky to fully understand and harness, it’s actually more straightforward to track kilograms and not just the elusive calories/kilojoules.
So, let’s say you consume 3.5kg of food/drink everyday. You also inhale approximately 600g of oxygen per day too. All in all, you are ingesting in one form or another 4.1kg of “stuff” (so sciencey).
This stuff, when being digested etc, will also create CO2 in your body, as well as water. And your own metabolism at rest will produce CO2 as well.
As such you need to expel your 4.1kg of stuff and then some if you want to lose weight.
Sounds like a lot, but get this: you actually exhale about 200g of carbon dioxide when you sleep. This is good news, as we want to body to create CO2 to lose that fat. Otherwise, your body will just store it, without being stimulated to break it down in the metabolic process.
The only conscious means of increasing the amount of CO2 created by your body is to move more. Moving your muscles improves your metabolic rate, and so helps to speed the process up.
This actually isn’t as much hard work as it seems. Your metabolic rate doubles when you get dressed, so you actually exhale more CO2 just by getting ready for work. Doing proper exercise has more of an effect, of course.
Going for a walk can increase your resting metabolic rate by a whopping 300%, but even doing household chores works your muscles and boosts your rate without even trying.
So there you go
You breathe out the byproducts of fat burning. Bear that in mind the next time you are walking up the stairs, or doing the hoovering. If you want to boost your metabolism, check out our blog with some of our Auro top tips.