Nutrition Explained: Carbohydrates

An easy-to-understand guide about the basics of nutrition. If you want a healthy lifestyle, this is the best place to start from!

Happy beginning of the week everyone! What a better way to start a busy week than with a little  bit of extra knowledge? I know, I know you are tired, it’s Monday morning and all you can think about is a cup of coffee or tea to keep you going for the day, I get it. But I promise I will try to keep this as simple as possible and you will thank me later! 😉

So, today I want to focus my attention on the main bulk components of the food we eat, in other words where most of our energy is derived from: macronutrients. Macronutrients are composed of carbohydrates, proteins, fats and alcohol. Do these names sound familiar to you? You may have heard them thousands of times, but still you are not too sure about what their role is, or you may have never heard of them before, or you may already know everything about it, either way you can find out a bit more in the following paragraphs and in the following posts. There is quite a lot to say about macronutrients, so today I will only be focusing on carbohydrates. I will upload more information about the others in my upcoming posts.

Carbohydrates

Carbohydrates are the main source of energy in our diet, they are the reason we have the energy to walk, to run, (to look after our kids, although for this you may need caffeine too!) and so on. So, when we eat a food containing carbohydrates, our body receives instant fuel that will give us all the energy we need. And because carbohydrates are the main source of energy we rely on, our body has to make sure that it has enough of it stored. Think of it as a fuel tank, you wouldn’t want to run out of fuel in the middle of a motorway, would you? So, our clever body stores all of the excess carbohydrates as glycogen in the liver and the muscles and as fat (oh, yes the famous fat). I guess there is no need for me to tell you where the fat gets stored right? Well, I will tell you anyways, fat gets stored in fat cells known as adypocites that are found all over the body.

Carbohydrates include sugars (monosaccharides and oligosaccharides) and polysaccharides.

Monosaccharides are the simplest form of sugar you can find and they are the building blocks for oligosaccharides and polysaccharides.  Glucose, galactose and fructose are the most common monosaccharides and are what more complex sugars are made of. And here is where we find oligosaccharides, which are sugars made of 2 to 10 monosaccharides units. Now, I don’t want to make it even more confusing, but check this out (the following are all oligosaccharides made of two monosaccharides):

GLUCOSE + FRUCTOSE = SUCROSE (the most common sugar used in kitchens)

GLUCOSE + GALACTOSE = LACTOSE ( the main sugar found in cow’s milk)

GLUCOSE + GLUCOSE = MALTOSE (can be found in germinating seeds)

Sucrose is what we refer to as granulated sugar, it is usually refined from sugar cane and roots of sugar beet, but it also naturally occurs in many fruit and vegetables.

You may be familiar with lactose, which is the main sugar found in cow’s milk, to which many of us are intolerant to. Well, now you know what it’s made of, pretty cool, huh?

Now, to the last of the carbohydrates: polysaccharides. They are the most complex of all carbohydrates, from a chemical point of view, as they contain more than 10 monosaccharides linked together. They include starch, glycogen and cellulose. Ever heard of them? Let me get in a bit more details.

Starch is mainly found in plant foods such as potatoes, corn, wheat and rice and it’s how plants store their carbohydrates. When starch is mixed with water, it creates a thickening, jelly-like agent, which binds and sticks to the food. That is why, when you cook pasta or rice, it tends to stick together, or that is why you use flour as a thickening agent to make sauces. Again, pretty cool hey?

Glycogen is how animals (and humans) store carbohydrates. As mentioned earlier, in humans, glycogen is stored in the liver and in muscle cells. Whenever we run low on energy, our body breaks down the glycogen into simpler sugars and use them as energy. Because glycogen is such a complex carbohydrate, the body requires more energy to break it down into monosaccharides and use it as fuel. In other words, more calories are burnt when the body uses glycogen as its main energy source, as supposed to simple sugars (such as monosaccharides and oligosaccharides). So let’s say you wake up in the morning, after a whole night of fasting and decide to go for a run. At this point, your body doesn’t have any ready-to-use fuel, so if you were to exercise now without having any breakfast, you would be burning more calories than if you had a full stomach. It’s not exactly pleasant though, so I will leave it up to you!

Cellulose is a non-digestible polysaccharide in humans and it’s what make up dietary fibers. You probably have already heard of fibers and you may know how important it is to have a diet high in fibers. Why do we need them if we don’t even absorb them? Well, fibers help to stabilize blood sugar levels, and decrease our request for insulin, which is the hormone involved in using and storing the sugars in our bloodstream (insulin is what helps sugars get stored as fat). Dietary fibers are also beneficial for our intestine, as they help with regular trips to the toilet (if you know what I mean). Also, they have been proved to decrease the risk of colon cancer and to reduce bad cholesterol. Fruit, vegetables and wholegrains are all foods rich in fibers, so make sure you stock up on them!

How much carbohydrates should I eat in a day?

Carbohydrates provide 3.75 kcal/g and as I already mentioned, they are the main source of energy our body relies on. Therefore, they should make up 45% to 65% of our daily calorie intake.

To  make things more simple, here is a nice picture that shows how much of each food category you should consume in a day:

So, that’s all for today, I hope you found this interesting and stay tuned, as I will be talking about protein and fats over the next days!

Monica

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