Today I realised that I didn’t really know what a carbohydrate was.
I knew they were delicious. I knew that I should try and eat complex ones instead of simple ones, and I had a vague understanding that carbs had something to do with sugar.
If you know what a monosaccharide is and how the glycemic index of the food you eat relates to your insulin resistance, now’s the time to stop reading.
Otherwise, here’s what I learnt today.
Carbohydrate is the food category for sugars, and molecules which your body breaks down into sugars.
Carbohydrates can be simple or complex.
Simple carbohydrates are broken up into two categories; monosaccharides which include glucose, fructose and galactose; and disaccharides including lactose, maltose and sucrose, each which are each a combination of two monosaccharides.
Complex carbohydrates have three or more of these simple carbohydrates strung together, and are broken down into to further categories; oligosaccharides and polysaccharides.
During digestion your body breaks down the linked sugars within complex carbohydrates into their simple parts so that they can be transferred into energy.
As these carbs are processed, your blood sugar rises. The simpler the carbohydrate, the faster your blood sugar spikes.
These complex polysaccharide carbohydrates are not all created equal either.
Starch and fibre are both polysaccharides sourced from plants, each contain hundred to thousands of monosaccharides connected together, but the way in which these monosaccharides are linked together varies greatly.
The linkages in starch (which is found in foods like white bread and pasta) are called alpha linkages. Alpha linkages are a weak bond which is easily cleaved by your digestive enzymes.
On the other hand, fibre (think green vegetables) is connected up by beta bonds, which cannot be broken down by your body.
As a result of this difference, starch and fibre have quite different effects on your body.
The way we measure this effect is by rating foods on their glycemic index.
Glycemic index refers to the amount that a certain food raises your blood sugar.
Starchy foods like crackers, white bread, pasta or soft drink have a high glycemic index.
Foods with indigestible beta bonds like fruit and vegetables have a low glycemic index.
The foods with the lowest glycemic index are proteins like meats, eggs and fish.
When blood sugar rises, our bodies release a hormone called insulin from our pancreas. Insulin serves as one of the body’s main tools for regulating blood sugar.
It prompts your muscle and fat cells to let glucose in, and jumpstarts the process of transforming sugar into energy.
The degree to which a unit of insulin lowers blood sugar informs your insulin sensitivity.
Basically, insulin tells your muscle cells to eat the sugar you’ve just consumed.
We can measure how well insulin does its job my measuring insulin sensitivity.
Insulin Sensitivity is the degree to which your blood sugar goes down in response to a unit of insulin being released into your system.
If your blood sugar drops dramatically in response to insulin being secreted, you have high insulin sensitivity.
The problem with eating too much junk (simple carbohydrates) is that it can cause your insulin sensitivity to decrease.
When insulin sensitivity falls too low, this is known as insulin resistance.
When carbs are introduced to an insulin resistant body, the pancreas continues to create insulin, but cells (especially muscle cells) are less and less receptive to it.
When insulin can’t do its job, it can’t help convert carbs into energy. Blood sugar fails to decrease and blood insulin levels continue to rise.
Insulin resistance leads to a condition called metabolic syndrome, which involves high blood pressure, high blood sugar and increased waist circumference, and also increases risk of type two diabetes and cardiovascular disease.
Not fun stuff.
If you’re having trouble wrapping your head around that, check out this awesome illustrated video from TED-Ed which spelt it out for me.