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Carbohydrates Facts for Nutrition

This blog post will cover the facts around carbohydrates, its effects on the body and the functions it has.

Let's start off by understanding the functions of carbohydrates (carbs):

  • Carbs main use for the body is for energy. The simplest form of carbs when they are broken down by the body is glucose (sugar) and that is used as energy for the body.

  • Energy storage. Glucose is stored in the liver and muscles to be used for energy. Excess available carbs will be converted and stored as adipose tissue (fat)

  • Protein-sparing activity. Having carbs present will spare protein from being used as energy and will allow protein to do its proper job for recovery.

When it comes to carbohydrates, there are two main categories, which are simple carbs and complex carbs. Another term you may have heard of is low GI and high GI. GI stands for Glycemic Index which measures the effect of specific carbohydrate foods on blood glucose, and reflects how quickly the certain carb is digested and absorbed as glucose into the blood. Below is a graph that shows the effect of low GI and high GI carbs on blood sugar.


As we mentioned above, the simplest form of carbs is glucose. Simple carbs are sources that are quickly broken down in the body to quickly reach the simplest form of glucose. They are foods that are known as High GI as they are broken down quickly and enter your blood as glucose after you have eaten it. As you can see in the above graph, high GI foods cause a spike in the blood sugar levels which means that your body needs to quickly produce insulin (hormone that helps store glucose) in order to keep up with the demand of glucose in the blood. Regular consumption of simple carbs may cause your pancreas (organ that produces insulin) to be overstressed and cause your muscle cells to be resistant to insulin. This is due to the high amount of insulin that needs to be produced at once, your pancreas cannot keep up. Also, the more your cells are excessively exposed to insulin, the more chance they will end up being resistant to it. Constant and excessive exposure will always lead to resistance. It's like when you go to sleep with a loud fan, it is annoying at the start, but since you are constantly exposed to the noise, you will soon be resistant to it and it won't bother you, you'll fall asleep.This is how diabetes start to happen and this is also how obesity happens.

Simple carbs should be avoided as much as possible due to these effects. Many of us crave an energy hit throughout the day, so we always go for something sweet as a 'pick me up', but all that does is cause a spike in our blood sugar. We might feel like we have energy for a short period of time, but since the glucose is quickly absorbed, it means we will quickly fall back to a state of lethargy. Then we look for something else, this isn't helpful for our bodies to constantly produce insulin. Obesity and diabetes is a risk from eating simple carbs.

The only time when simple carbs can come as a benefit to your body is during times of high intensity or prolonged physical activity. As stated above, the main function of carbs is energy, so when our bodies are looking for and needing carbs the most, it is when we should give it to them as quickly as possible. That's when simple carbs come in handy.

For example, if you're running a marathon, it is a good idea to carry some carbohydrate gels with you as you run to consume during the run. Carbohydrate gels are pretty much sugar. You may also see people eat ice blocks or bars during long runs and cycles, this is to feed their body with what it currently needs. As we eat the simple carbs, they are broken down and absorbed quickly into the blood and quickly used up by the muscles, meaning that they will not float around in the blood waiting for high insulin production to bring blood sugar down.

Sources of simple carbs:

  • Sugars (high fructose corn syrup, lactose, honey)

  • Sweet and lollies

  • Cakes and Pastries

  • Bread

  • Chips

  • Confectionery

  • Biscuits and cookies

  • Canned goods

  • Any sort of muesli bar, granola bar etc


Complex carbs take longer to break down in the body. This means that it is slowly absorbed by the body and into the blood. From the graph above, we can see that low GI carbs don't spike blood sugar that much, it is more sustained and it takes longer for the body to absorb it into the blood as it is harder for your body to break down. This can bring about a feeling of satiety (fullness) as it is not quickly absorbed. Along with protein, complex carbs will help you feel fuller for longer so you don't crave an energy hit.

Since complex carbs are harder to breakdown, only limited of glucose goes into our blood at any given time. This means that our blood sugar does not spike and our pancreas does not need to work overtime to produce insulin. Over time, our pancreas will not be overstressed due to high insulin production and our muscle cells also will have less chance to become resistant. This is due to low exposure of insulin on the cells. Eating more complex carbs will decrease the chance of diabetes in the future.

It is also great to eat complex carbs before and after exercise. This is because complex carbs provides more sustained energy pre workout. It also provides refueling post exercise in a sustained manner.


Fibre is a complex carb also and it is very important to health. Fibre is important for gut health and helps to prevent any diseases of the bowel. Fibre acts as the cleaner for our bowels, it helps get rid of all the waste. This protects the bowel linings as fibre binds harmful substances and reduces their contact with the lining of the bowel.

Fibre is bulky and not all of it is absorbed into the blood. This means that it helps clean the bowel as it goes through it to become eliminated as faeces. Dietary fibre absorbs water from bowel and makes faeces bulkier and softer.

Other benefits of fibre are: - they serve our probiotics which are healthy gut bacteria needed in our bowels. - lowers cholesterol as bile acids (made up of cholesterol) are excreted with fibre. - anti-obesity activity as fibre is slower to digest which decreases hunger.

Sources of complex carbs:

  • Steel cut oats

  • Brown rice

  • Sweet potato

  • Quinoa

  • Chia seeds

  • Bran

  • Beans (black beans, chickpeas, kidney beans etc)

  • All vegetables

The general rule of thumb is that if you want to enjoy carbohydrates, enjoy them in their most natural and unprocessed form. For weight loss, you should be aiming to cut down carbs as much as possible, for the limited carbs you do eat, make sure they are complex carbs and fibre in their natural state.

To understand how carbohydrates truly affect weight gain, read Understand how Weight Loss Works blog.