What are carbohydrates? What are the common types of carbohydrates, and what is their function? Which foods are good sources of carbohydrates? And are they good or bad?
The media spends a lot of time villainising carbs. And many popular “diets” over the past decades recommend low carb or no carb eating patterns.
Therefore its no wonder that the majority of my clients come to me fearing carbs. However, each and every time, I find that by exploring the science behind this nutrient with them, and breaking it down to the level of molecules, they are much more confident in choosing healthy eating patterns that work for them and their energy levels.
Knowledge is power!
So stay tuned, because in this post I will be doing the same for you. We will discuss what the meaning of carbohydrates is. We will explore the role and function of carbs in our diets, and go through the science of carbohydrate metabolism. All to help you make healthier decisions every day!
Welcome back to my series on the nutrients behind the diet. In these blog posts and Youtube videos, I help you to reach that “aha” moment that will allow you to piece together your healthy eating habits! I started this post series a little while ago, and you can find the links for the various posts in the series here: nutrients overview, fats , proteins, Vitamin C and Vitamin D.
Are you interested in learning more about nutrition or are finding ways to eat healthier? Then this post series will support you in making more informed choices! So in today’s post, we will take a closer look at what carbohydrates are, and their role in our diets.
What are Carbohydrates?
What is the meaning of carbohydrates? And are they good or bad? In this video, we will explore the role of carbs in our diets, go through the science of carbohydrate metabolism and help you make healthier decisions every day!
Lets dive straight into the carbohydrate fact file:
- Carbohydrates are macronutrients, meaning that we need it in relatively large amounts in our diet. As in, we measure our carbohydrate needs in grams rather than micrograms.
- Carbohydrates provide us with energy, also known as calories. We get 4 kcal per gram of carbohydrate.
- The structure of carbohydrates are mostly made of the elements carbon, hydrogen and oxygen.
- There are actually many types of carbohydrates, each with a slightly different effect. And it is the type, quality and quantity of the carbs you eat that is important to consider when making diet choices! So when looking at the types of carbohydrate, we usually look at their structure. Carbs often make chains, and we give them different names based on the length of these chains. Some of the smallest carbs are called monosaccharides. Two of those stuck together are called disaccharides. And a much longer chain of carbohydrates is then called a polysaccharide.
So if the health effect of carbohydrates is based on their type (meaning their structure), then we should explore the different types and their sources!
First of all, the smaller types of carbs called mono and disaccharides often fall into a food group the we commonly call “sugar”.
This is the type of carbohydrate that most adults and children eat too much of. It is known to have a bad effect on our health if you eat too much of this.
Refined sugar (usually meaning carbohydrate taken from sugar beets or cane), is often added to foods. This added sugar is found in a range of foods including cakes, biscuits, chocolate, sweet breakfast cereals and flavoured yoghurts. Many drinks also have sugar added, for example your fizzy drinks. Sometimes we add sugar to food ourselves at home, but our main source of sugar is added by the food manufacturers.
Some foods are a natural source of sugar, meaning that these carbohydrates are naturally found in the foods. These include honey, syrups (such as maple or agave syrup), fruit juices and nectars. These still count as free sugars and have a similar effect to our health as added sugar.
Foods such as milk, fruit and vegetables are also sources of sugar, but these examples have less of a bad effect on our health.
We will take a look at some of the effects of these sugars on our health later in this post.
The next type of carbohydrate foods we will look at is starch.
These are polysaccharides, meaning their structure forms a long chain of lots of smaller carbohydrates.
We often find sources of starch in foods from plants, for example potatoes, grains, rice. We then also get starch from foods made from these plants, with bread, pasta and breakfast cereals being good examples.
And then the final type of carbohydrates are fibre.
Fibre is a very complex polysaccharide structure, with lots of bonds between the different chains of smaller carbs. We often find fibre in the cell walls of plants. And so foods that are a good source of fibre include wholegrain bread, wholegrain pasta, vegetables with the skin on them and pulses such as beans, peas and lentils for example.
So when we look of the meaning of carbohydrates in our diet, we need to look at why we need carbs! We need to look at the function of carbohydrates!
Carbohydrates play an important role in our energy metabolism, in managing our risk for certain diseases and in controlling our calorie intake!
We will look at our energy levels first. I find that this is where the meaning of carbohydrates and its role on our health often starts hitting home.
We are going to have to go on a little journey through our digestive system to truly understand what happens when we eat, digest and metabolise different examples of carbohydrate sources.
When we eat carbs, and all sources of carbs are similar in this way, our digestive system tries to break them down into glucose (also known as sugar). Once it is digested into glucose, we absorb it into our blood stream. Now that the glucose is in the blood, it moves from there into our cells with the help of insulin.
Once the glucose is in the cell, we use it for energy, fueling all our activities from running, to simply breathing. It all uses energy!
Any glucose that we do not need to use “there and then” can be stored in the muscles and in the liver.
However, if we eat much more glucose than we need at that time, we can also turn the glucose into fat and store it for later.
Now lets take a look at what happens to our different food sources of carbohydrate as we eat them:
First, here is a little graph of our healthy blood sugar levels. The green line is a healthy blood sugar level. Coming towards the upper and lower red line means our blood sugar levels are getting too high or too low.
So, we now decide to eat a few biscuits, a common food source of sugar. Lets take a look how this biscuit is broken down and absorbed from our gut:
As our biscuit contains lots of sugar, our body doesn’t need to work very hard to break it down into glucose. As you can see here, some of the sugar is already found as glucose and can immediately be absorbed into our bloodstream.
So lets look then at what happens when the carbohydrate enters the bloodstream.
Our sugars rise quite quickly. You can see it hitting that top red bar there. Our body doesn’t really need as much sugar as we have just had, so we can store some of it as fat for use as an energy source later on. However, because we are storing a lot of this sugar now as fat, our sugars start dropping rapidly. You might start feeling peckish again not long after those biscuits. This is simply because our body had such a rapid influx of glucose, which we couldn’t use up as fast as we absorbed it. As a result, we feel hungry again rather quickly.
Next, what would happen if we had decided to eat a white bread sandwich, an example of a food source of starch?
This food mostly contains starchy types of carbohydrates. This means it needs a bit of digestion before we can absorb it as glucose. So as you can see, each time we have managed to cut off one glucose, we can absorb it into our blood stream. But this process takes a bit longer and is slower.
Back to the chart, we can now see that our blood sugars are rising more slowly. And we are giving ourselves more time to use this energy up as it comes. We might still store some of this as fat, but likely not quite as much as with the biscuit. You may start feeling that hunger pang kicking in about 2 hours later this time.
And lastly, lets take a look at what would happen if we eat that salad with lots of veggies and some brown pasta, an example of a food source high in fibre.
This is what is would look like in our gut. There is some starch there, which we can start breaking down to glucose as we digest the meal. However, can you see how many more bonds need to be cut, or digested, before we can release a glucose? Some of that meal was definitely fibre. As the structure of this carbohydrate is much more complicated, it takes longer to digest. And often it passes through our gut mostly undigested.
Our sugars as you can see therefor rise slowly. And of course they take longer to reach their peak, meaning these carbohydrates are being used up at the rate they are absorbed. This leaves little to be stored as fat. As can expect, you will take much longer now to feel hungry. And this is not just because our sugars are dropping so slowly. It is also because that fibre is just sitting there, in our gut, filling up space and making us feel full.
Be aware that how much glucose we use up at any time can be affected by our activity levels.
For example, muscles that are exercising rely on carbohydrate as an important source of energy. Muscles have a store of glucose which they use up when active. The meaning of carbohydrates in marathon running is well known. You may have heard of a marathon runner hitting that “wall”: this is often when the glucose stores in the muscles are used up. So to continue running, a marathon runner needs quick acting carbs to help prevent that. This can mean that a sugary food may be needed at that time to allow for plenty of glucose to rush into the blood and to be available for the run.
Next, lets take a look at the function of carbs in relation to our risk of developing diseases.
Fibre is a very important part of a healthy diet. This is because it helps to keep our guts healthy. Eating enough fibre can help prevent constipation and can help move foods through our bowels. Also, some types of fibre, often found in oats and pulses is even linked to reducing blood cholesterol levels.
Diets that are high infood sources of fibre are shown through research to help lower your risk of bowel cancer, cardiovascular disease and type 2 diabetes. And many people don’t eat enough fibre in our day. While we should be aiming to eat up to 30 grams of fibre every day, most people get just under 20g!
And lastly, we can see that eating a diet high in fibre is also linked to lower calorie intakes. By replacing sugary and fatty foods with foods higher in starches and fibre, you can likely reduce the calories you are eating, and are at the same time likely going to feel fuller for longer!
It is important however to be careful about what you put on your wholegrain bread or into your brown pasta dish. It is often what we eat with our starchy fibre foods that can contribute to weight gain. So skip the Nutella on the bread for example, and avoid the creamy sauce on the pasta to get the most out of your healthy meal.
Now, what happens if I cut out carbohydrates, like they recommend in many diets such as the ketogenic diet, the Atkins diet or the Dukan diet? Do Low Carb diets work?
Well, we can most definitely survive without added sugar, but it can be very hard to completely avoid all types of carbs. This is because we find carbs in many foods, including typically healthy foods such as fruits, vegetables and dairy for example.
When we avoid eating carbohydrates, our body CAN use protein and fat for energy. In the long-term however, this can put us at risk of missing out on key nutrients from our diet. Meaning we are at risk of deficiencies! It would very hard to get enough fibre for example, which we already know is important for our gut health. Also, high fibre starchy foods, fruits, vegetables and legumes are important sources of nutrients such as b-vitamins, vitamin C, iron and calcium.
By avoiding carbs, many people start eating more high fat protein foods (such as meat and dairy) to replace these carbs. This is likely to increase how much saturated fat you eat, meaning you may increase your risk of cardiovascular disease.
A good alternative to a low carb diet really is to avoid overly sugary foods.
Instead eat healthy natural sources of carbohydrate such as fruits, vegetables, potatoes and wholegrains. This can help you feel fuller for longer and reduce your calorie intake. A balanced diet really is key! Eating some healthy fats, some protein with every meal and a large variety of fruits and veg and wholegrains is still coming out best when it comes research into healthy and sustainable diet patterns.
So how much carbohydrate should we be eating?
The World Health Organisation recommends that just over half of our daily calories come from starchy foods, fruits and vegetables. A healthy plate would look something like this: Half a plate of vegetables, a quarter plate of wholegrain carbs and a quarter of protein foods.
Just be aware that the advice in this video is generalised, meaning that some people may be recommended to eat differently to this. For example, there is emerging evidence to suggest that those with type 2 diabetes may benefit from a lower carbohydrate diet. This may be used to assist with weight loss, although it is not clear if this is a safe way to manage type 2 diabetes in the long term. We always recommend for everyone with diabetes to see a registered dietitian for specific advice on their diet. Ask your dietitian whether any specific dietary changes may be beneficial.
So as you can see, nutritional science is again bringing us back its recommendation to eat a well balanced diet. No nutrient in isolation is completely evil or great. They each have good and bad sides.
And it is important to remember that we don’t eat nutrients in isolation. We eat food – and we eat meals. We eat a balance of each of the nutrients, spread out over the day and over the week. By keeping that balance as healthy as we can, we are nurturing our bodies with all the nutrients it needs to function at its best.
I hope this post helped you learn more about what carbohydrates are, their role and function in our diets and in our health. Make sure that you subscribe to my Youtube channel! And if you hit that little bell button on my channel page, you will get notified when my next video comes out. I hope to catch you on my facebook, instagram, twitter and pinterest pages, where I’ll keep the conversation going until my next post!
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