You've probably heard that carbs are bad for you.

And there's a lot of us searching for signs they're good, possibly sugar, or just the devil.

But carbohydrates are your body's main fuel source.

So what do carbs actually DO when they pasta through your body?

Carbohydrates in our food fall into three categories: sugars, starches, and dietary fibre.

Sugars, like lactose, fructose, and sucrose, can be found in foods like milk, tangerines, and table sugar.

Starches and dietary fibre are both long chains of sugars.

And when we eat carbs, our saliva and stomach acid break long sugar chains down into short chains.

Once the food reaches the intestines, the pancreas releases an enzyme that breaks down the starches molecular bonds until the chains are turned into bonded pairs of sugar molecules.

But in fibre, the bonds between these molecules are different: They're stronger, can't be broken by our enzymes, and so they can't be digested.

Instead, they just pass through the rest of your digestive system, holding everything else together.

Once the starch is broken down, the small intestines release enzymes that break down the sugar molecules even more.

And then, they're absorbed into the bloodstream.

The most important of these sugar molecules is glucose.

All of your cells use glucose for energy.

And your brain uses about half of your body's sugar needs.

If you don't have enough glucose for your brain cells, you can get shaky, lightheaded, and confused.

But... what happens when you eat too much?

If your body has too much glucose, your pancreas releases insulin, which packages up glucose and stores it for later use: like when you're in between meals, or need more energy for things like thinking or exercise.

Some athletes carbo-load to have more energy stored for when they need it.

But in your brain, too much sugar can contribute to cell ageing and death, shrinking your brain and possibly contributing to dementia and other conditions.

Luckily, for most of us, our pancreas can release insulin to regulate our blood sugar levels so we don't have those problems.

But if you regularly eat more sugar than your body needs, you can develop insulin resistance and even diabetes.

So if you're worried about carbs being full of sugar, or making you fat, just remember that food is fuel, even carbs.

The key, according to most experts, is to eat carbs, protein, and fat in moderation, focusing on giving your body, and brain, the fuel it needs, without going overboard.