What are carbohydrates?

First, are carbs and carbohydrates the same thing?

Yes. These names refer to the same macronutrient, made from carbon, hydrogen and oxygen. Metabolising these compounds supplies energy and produces carbon dioxide and water.

What do carbohydrates do?

Their main role is supplying energy or fuel for bodily functions. They provide readily usable energy: glucose is metabolised to generate ATP through pathways including glycolysis. Cells use this ATP for the energy they need.

Glucose is also a major energy source for the brain.

That helps explain why removing carbohydrates entirely because of a fashionable TikTok is not a sound starting point.

What types of carbohydrate are there?

You may have heard that not all carbohydrates are good.

Rather than labelling them good or bad, consider which type suits a particular time and purpose.

As we often say, nutrition does not have a single answer for everyone: too many individual factors are involved.

We can explain the differences between simple carbohydrates and complex carbohydrates without assigning moral labels.

Simple carbohydrates

These are smaller molecules that can supply energy readily, which may be useful just before training.

They include:

Monosaccharides:

Examples are glucose, fructose and dextrose. These small sugars cannot be hydrolysed into smaller carbohydrate units and can provide a rapid energy source.

Disaccharides:

These consist of two joined monosaccharides, which can be separated by hydrolysis.

For example, lactose combines glucose and galactose. To use it, the body separates these units with the enzyme lactase.

This group also includes maltose and sucrose, or table sugar.

If you have little digestion time before exercise, readily available sugars can be useful. During long sessions or competitions, glucose tablets or gels can help maintain carbohydrate supply.

Complex carbohydrates

These contain longer chains of three or more sugars connected by bonds called glycosidic bonds.

Larger molecules require digestion, which can make energy release slower.

They include:

Oligosaccharides:

Chains of several monosaccharides, found in vegetables and some fruit, including bananas.

Polysaccharides:

Chains of 10 or more monosaccharides, including carbohydrates in oats and other wholegrains.

Digestible complex carbohydrates must be broken down to release glucose. This can take more time, helping provide energy over a longer period.

Glucose not immediately used for energy can be stored in the liver and muscles as glycogen.

What is fibre?

Dietary fibre includes non-digestible carbohydrates and lignin. Human digestive enzymes cannot break it down in the same way as digestible starch.

Is all fibre the same?

No, my friend.

Two broad types are:

Soluble fibre:

It can feed gut bacteria and slow gastric emptying by attracting water and forming a gel. Sources include fruit, nuts, pulses and seaweed.

Insoluble fibre:

It retains fluid, increases stool bulk and supports bowel movements. Sources include wholegrains, vegetables and pulses.

Foods containing carbohydrates

Want to add more carbohydrate to your diet?

Simple sugars occur in fruit, milk and processed foods containing added sugar. The latter are generally less useful as everyday staples.

Complex carbohydrates occur in wholegrains and grain-like foods such as brown rice, quinoa and buckwheat, as well as pulses and vegetables.

Carbohydrates in an athlete’s diet

If you are an athlete, you probably know that carbohydrate plays an important role in your diet.

Exercise increases energy expenditure, and carbohydrate is a useful fuel, alongside adequate protein and fat.

For a pre-workout meal shortly before exercise, simple carbohydrates can be useful when digestion time is limited. If there are several hours before training, complex carbohydrate sources may help maintain blood glucose and provide more sustained energy.

Are carbohydrates only useful before training?

No. They are also part of a good recovery meal, helping replenish glycogen stores used during exercise.