Carbs – love them or hate them, we all need them. Despite a wealth of low-carb fad diets there’s no good reason for avoiding carbohydrates. The key is in choosing the right ones.
Our cells - every single cell in your body – run on carbs. Your body breaks down carbohydrates into glucose and other molecules and it’s glucose that is used as cell fuel. But that’s not an invitation to feast on sugary snacks!
Not all carbs are the same
A carbohydrate is a molecule containing carbon, oxygen and hydrogen. They can be either simple (sugar) or complex (starch and fibre), depending on how many molecules are bound together, the different types and quantity. Both simple and complex carbohydrates can be a part of a healthy diet.
As carbohydrates are digested, they release glucose into the bloodstream. Some foods release it faster. Based on this, a measurement of glucose-release speed has been invented – the glycemic index (GI). Foods that release glucose fast have a high GI and are a good source of fast energy – dates, refined cereals, potatoes. Foods that release it slowly have a low GI and are good for sustained energy release over a longer period of time – most fruit and vegetables, pulses, nuts and seeds. And then there’s a whole range of foods with a medium GI – wholegrain products, brown rice, porridge.
Simple carbs - sugars
Simple carbs are either single sugar molecules (glucose, fructose) or two sugar molecules linked together (table sugar, milk sugar – lactose). They are digested fast and we should therefore watch our intake - with the exception of fruit and vegetables. These naturally contain fructose, a simple sugar, but if eaten fresh and whole they also supply a wealth of complex carbohydrates along with many other nutrients which slow down the speed of sugar release.
Fruit and vegetables are among the healthiest foods so there’s no need to limit their intake. They are best eaten raw, lightly cooked or blended in a fresh smoothie but avoid canned varieties.
Beware of fruit juices as 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 smoothies – many are mostly juice and have only a fraction of whole fruit in them. They are also pasteurised. You’re better off making your own!
These consist of many molecules linked together in complex structures and usually mean starch and fibre. The difference is that we can digest starch well, your body breaking it down into single glucose molecules, whilst we cannot digest fibre.
Starch is naturally a part of many foods, such as wholegrains, pulses, root vegetables, pumpkins, courgettes and so on, all of which belong in a healthy diet. These foods contain starch along with many other nutrients and your body digests them more slowly. On the other hand, refined starches used as a binding ingredient in foods such as biscuits, processed snack foods and sweets, are extracted from their natural sources in a process that strips off all the other nutrients. This ensures they are not very healthy because you digest them quickly, which may result in high blood sugar levels.
Too much sugar in your blood at any given moment - more than your cells can take up - and your body will try to restore the balance by removing some of the sugar and storing it as fat.
Dietary fibre is the name for a large group of complex carbohydrates that we cannot digest. Fibre is naturally found in unrefined plant foods but never in animal-based foods. Even though we can’t digest it, it’s a very important part of any diet because it keeps the digestive system healthy and improves our energy metabolism by slowing down sugar absorption. This helps with healthy weight management, can reduce blood cholesterol and the risk of heart disease, some cancers (particularly colon cancer) and diabetes and encourages the 'good' bacteria in our gut.
It’s easy to get plenty of fibre from fruit and vegetables, wholegrains, pulses and nuts and seeds. There’s absolutely no need to splash on supplements as all you need is in plant wholefoods!
There are two types of fibre – soluble and insoluble. Soluble fibre dissolves in water and forms a gel, which can help make you feel fuller for longer after a meal and makes stools soft and easier to pass. It’s also fermented in the colon by bacteria, resulting in by-products that are beneficial to health. Soluble fibre is therefore a prebiotic - something that promotes beneficial bacteria by providing them with suitable ‘food’ in the intestine. The best sources of soluble fibre are wholegrains, fruit, pulses and root vegetables.
The other type of fibre is insoluble and doesn’t dissolve in water but absorbs it. This means it increases stool bulk and helps to keep you ‘regular’. It’s also partially fermented by gut bacteria which helps the good ones to prosper. The best sources are wholegrains, breakfast cereals, unpeeled fruit and vegetables, nuts and seeds.
How to carb up well
We have evolved to thrive on a diet full of natural carbohydrates so it’s best to build your diet around unprocessed or minimally processed foods, such as wholegrains, fruit and vegetables, pulses (lentils, beans, peas), which release their energy gradually and promote good health by providing vitamins, minerals, fibre, antioxidants and many important phytonutrients.
On the other hand, processed or refined foods, such as white bread, pastries, processed snacks, cakes, sweets, fizzy and sugary drinks, are full of ‘bad’ carbs that turn into sugar fast and may contribute to weight gain, heart disease, diabetes and some types of cancer. Like any other junk food, if you have them occasionally, you’re fine 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. A steady energy supply from good carbs also makes you feel good, physically and mentally. Carbs ahoy!
Low-carb, ketogenic or paleo diets usually focus on high protein and fatty foods and severely restrict the intake of carbohydrates. This forces your metabolism to change and draw the energy mostly from fat and protein, which makes you less hungry and leads to weight loss. But – and there’s a big but! – these diets are effective only for short term weight loss and have a whole range of unpleasant adverse effects such as constipation, headaches, kidney fatigue, bad breath, decreased insulin sensitivity, increased cholesterol levels and more. In the long term, they are not any more effective for weight loss and maintenance than low-fat diets which don’t have these nasty side effects and allow your body to function naturally.
Healthy fast energy for athletes
During long training or endurance races, athletes often need to replenish energy fast and that means eating fast carbs on the go. The best natural sources are dates, bananas, mashed sweet potatoes and raisins. These foods help to provide energy to fuel the performance when the body’s own energy stores start running out.
However, if your workouts don’t last longer than 60-90 minutes (depending on intensity), you probably don’t need to worry about it.