Reading Time: 6 minutes Most people don't eat enough fiber (Photo: Adobe. Do not use without permission)
Reading Time: 6 minutes

Carbohydrates – some avoid them, others love them, many are confused. 

It’s understandable as mixed messages bombard us every day and low-carb products are flooding the market. 

Here’s what you need to know and how to make sense of it all.

1. Carbs are essential

Your cells – every single cell in your body – run on carbs. Carbs are our primary fuel that we need and thrive on. When you eat carbs, your body breaks them down into glucose and other molecules and it’s the glucose that is used as cell fuel.

Carbs provide energy for all vital reactions in your body, keep your brain running and are stored in your muscles as a ready-to-use energy source. This storage form of glucose is called glycogen and when you’re physically active, it can fuel your body for about one or two hours, depending on the intensity of your exercise. 

When it starts running out, it’s when you start feeling tired. After you’ve eaten, your body replenishes these muscle stores again so it’s important to have some good carb sources post-training.

2. There are three types of carbs

A carbohydrate is a molecule containing carbon, oxygen and hydrogen. They can be either simple (sugar) or complex (starch and fiber), depending on how many molecules are bound together and their different types.

1) Simple carbs – these have a small molecule which means your body digests them fast. They give you a sugar rush but the energy doesn’t last. As a result, you feel tired and crave more – not ideal. 

Examples are table sugar, syrups, sweets, sugary breakfast cereals and cakes. This category also includes white flour products – bread, pastries, pies. White flour doesn’t contain sugar as such but because it’s made out of grains that have been stripped of all their outer layers and most nutrients and then ground to fine powder, your body digests it super fast and the effect on your body is on par with sugar.

You don’t really need these carbs unless you’re in the middle of an intense workout, climbing a mountain or running a marathon – then they provide the much needed fast energy. In ‘normal’ life, it makes sense to avoid simple carbs to avoid energy highs and lows, and unwelcome weight gain.

2) Complex or starchy carbs – these carbs combine many molecules into very long chains so your body breaks them down slowly and releases glucose gradually. These are the best source of long-lasting energy throughout the day so should be your carbs of choice. 

They are found in wholefoods such as wholegrain bread, oats, brown rice, fruit, vegetables, beans, lentils and sweet potatoes. These foods provide a healthy package deal – their complex carbs come together with fibre, protein, vitamins, minerals and antioxidants. It means they give you healthy energy, maintain steady blood sugar levels, are good for your digestion and overall health.

There’s absolutely no reason to avoid these carbs. They should be your staples at every meal

3) Fiber – a diverse group of many types of complex carbs that we cannot digest. Fiber is important because it keeps our guts healthy by feeding the beneficial bacteria that live there, slows down energy release from foods and regulates blood sugar and fat. 

Fiber is absolutely crucial to a healthy diet. The good news is that it’s an essential component of plant wholefoods (fruit, vegetables, pulses, whole grains, nuts and seeds) so if you base your diet around them, you won’t have to worry about a lack of fiber.

3. How to choose the ‘good carbs’

It may seem clear – white, refined carbs are bad, wholefood carbs are good. But how about fruit or your favourite granola? And are ‘healthy’ drinks a good carb source?

It’s easy to get confused about carbs! Especially as so many products are advertised as healthy yet are far from it. It may seem obvious but always read the ingredients – if sugar is high on the list, it means there’s a lot of it in the product. 

At the same time, just because something has a healthy ingredient in it, it isn’t necessarily good for you. For example flapjacks, granola, and oat biscuits are all oat-based yet are usually loaded with sugar or syrups. It’s better to go for natural muesli, oat and nut bars sweetened with dried fruit, and if you want to eat those biscuits, perhaps just have a couple at a time.

Fruit is another source of confusion. It contains simple sugars which is why some people believe it should be avoided but that’s completely unnecessary and would rob you of many important nutrients. Fruit contains complex carbs and fiber, which slow down the speed of its sugar release, and offers many vitamins, minerals, antioxidants and beneficial phytonutrients. Fruit is among the most natural foods for us so we should eat several portions daily.

It’s a different story with fruit juices – they contain almost no fibre and unless they’re freshly made, they undergo a pasteurisation process that destroys most of the goodness. The result can be little more than sweet water. And it’s similar for convenience, long-life smoothies – many are mostly juice and have only a fraction of whole fruit in them. On the other hand, if you make a fresh smoothie at home, you’re getting all the goodness of the fruit and nothing is lost so it’s a super healthy choice.

When it comes to main meals, always go for wholegrain versions – wholemeal bread, brown rice, whole wheat pasta, jumbo oats, quinoa, etc. Potatoes can also be a part of a healthy diet but you do digest their carbs fairly fast so it’s best to combine them with vegetables that slow down the whole process – sweet potatoes and other root vegetables. Be carb-smart and there’s no need to give up anything.

We should eat several portions of fruit a day 

4. Sugar is addictive

When you eat sugar, your brain releases the hormone dopamine that makes you feel good and makes you want to repeat that pleasurable experience. This stems from our evolutionary history because sweet foods are a good source of energy and that used to be crucial for our survival. 

However, now there’s too much sugar everywhere and this brain reward is a bit of a trap. Many addictive drugs act in a similar way but the dopamine response to sugar isn’t as big as with hard drugs. It means that your sugar cravings have a biological explanation but also that it isn’t that difficult to break your sugar habit.

The brain reacting to sugar is one part of sugar ‘addiction’, the other is our taste buds – in other words the level of sweetness we’re used to. The latter takes some time to reprogram but once you’ve done it, you’ll be surprised just how much your taste has changed. 

Some people decide to cut sugar out completely, some simply reduce the amount they consume to a minimum. There’s no one-size-fits-all approach so it’s up to you but gradual reduction offers a gentler transition than going ‘cold turkey’. If you put a teaspoon of sugar in your tea or coffee, try halving the amount and after three weeks, halve it again. Why three weeks? That’s how long it usually takes to build a new habit.

5. Low-carb diets are dangerous

Low-carb, ketogenic or paleo diets are usually based around foods high in protein and fat, and severely limit carbohydrates. This forces your metabolism to switch gears and draw energy mostly from fat and protein, which makes you less hungry and may lead to weight loss. 

Your body can do this for a while but it’s not a natural way for your metabolism to work. It’s why these diets are effective only for short-term weight loss but if followed for long periods of time, they have a whole range of unpleasant adverse effects such as constipation, headaches, kidney fatigue, bad breath, increased cholesterol levels, increased risk of heart disease, cancer and even premature death (Bilsborough and Crowe, 2003; Farhadnejad et al., 2019; Mazidi et al., 2019).

Take-home message

We have evolved to thrive on complex carbohydrates so it’s best to base your diet around their natural sources, such as whole grains, fruit and vegetables, and pulses (lentils, beans, peas), which release their energy gradually and promote good health by providing vitamins, minerals, fibre, antioxidants and phytonutrients.

On the other hand, refined carbs, such as white bread, pastries, processed snacks, cakes, sweets, fizzy and sugary drinks, are bad news as they turn into sugar fast and may contribute to weight gain, heart disease, diabetes and some other chronic diseases. If you have them occasionally, it’s not a problem but they shouldn’t be your daily go-to choice.

Our bodies run on carbs so don’t avoid them. Choose the good ones and you’ll be the best you can be – feeling good, physically and mentally, with plenty of energy to power your day.


Bilsborough SA, Crowe TC. 2003. Low-carbohydrate diets: what are the potential short- and long-term health implications? Asia Pacific Journal of Clinical Nutrition. 12 (4) 396-404.

Farhadnejad H, Asghari G, Emamat H, Mirmiran P, Azizi F. 2019. Low-Carbohydrate High-Protein Diet is Associated With Increased Risk of Incident Chronic Kidney Diseases Among Tehranian Adults. Journal of Renal Nutrition. 29 (4) 343-349.

Mazidi M, Katsiki N, Mikhailidis DP, Sattar N, Banach M.2019. Lower carbohydrate diets and all-cause and cause-specific mortality: a population-based cohort study and pooling of prospective studies. European Heart Journal. 40 (34) 2870-2879.

Veronika Charvátová

Veronika Charvátová MSc is a biologist and Viva! Health researcher. She has spent years uncovering the links between nutrition and good health and is an expert on plant-based diets.