Updated: May 31
There is conflict between supporters of a high carb and a low carb diet, and there are convincing arguments for both sides.
However in order to make the right choice, it is important to understand the different types of carbohydrates that exist and their functions.
Are carbs important? What type of carbs should you prioritise?
Here is a full break down of carbohydrates to help you understand what is going on in your body when you eat carbs.
What are carbohydrates?
Carbohydrates, or carbs for short, are plant foods made up of sugar molecules called saccharides. Their structures dictates how they are categorised and their function.
A carbohydrate has 4 calories per gram and is mostly used as energy for the brain and for high intensity activities like sprinting, or weight lifting.
How do carbohydrates work?
All types of carbohydrates are broken down by digestive enzymes (pancreatic and salivary amylase) into glucose. This glucose enters the bloodstream and stimulates the pancreas to release insulin.
It locks cells and allows glucose to enter various tissues. Glucose is then stored for later use in the form of glycogen for fuel, or converted into fat (if there is an overconsumption of carbs).
Little glucose remains in the blood to fuel the brain.
Glycogen is locked into the liver to fuel the brain and and stored in muscles to provide energy for muscle contractions.
Simple carbs or sugar
Sugar often has a bad reputation. Caution must be paid to its consumption, however mainly to the type of sugar eaten.
Simple carbs come in 5 forms : monosaccharide (single saccharide molecule), glucose (dextrose), fructose (fruit sugar) galactose, or disaccharide (pairs of molecules joined together), in the form of sucrose, lactose and maltose.
Simple healthy carbohydrates are found in foods such as fruits, vegetables and milk. Whereas less healthy simple carbohydrates can be found in sweets or cakes.
The composition of simple carbs give them a high glycemic index (what is the glycemic index) which means that it is quickly broken down into glucose and used by the body. That makes them the perfect snack if you need fast energy to perform a physical activity.
However it is important to note that simple carbs are lacking in vitamins, minerals and fibre, when compared to complex carbs, and so are a less effective source of energy.
Complex carbs or starches
Complex carbs are made up of multiple chains of saccharide molecules called polysaccharides (starches).
They are found in foods such as bread, rice and pasta.
Their composition and low glycemic index, make them slowly assimilated by the body to be used as fuel, making them perfect for breakfast as they supply us with a gradual supply of energy, which can last all day long.
They are also ideal for supplying gradual energy to support long physical activities such as walks or long runs.
Fibre is also a form of carbohydrate. Fibre is a Non Starch Polysaccharides or 'NSP’ and it contains 0 calories per gram.
In fact, the human digestive system lacks the enzymes to break down fibre, making it calorie-free, which means that they do not supply any energy to the human body.
Fibre can be soluble, like the soft fleshy part of fruits, which help soak up liquid in the digestive track. It helps absorb bile acids, cholesterol and fat.
Fibre can also be insoluble, such as the skin of vegetables and fruits. These insoluble fibres have a scrubbing function for the digestive system.
The RDA recommend that we consume up to 35g of both soluble and insoluble fibre per day. Consuming this level of fibre helps lower cholesterol and control blood sugar levels. A good intake of fibre also normalizes bowel movements and helps maintain our gut health.
Refined and unrefined carbs
Carbohydrates can be made in 2 different ways:
Refined carbs are the more processed kind of carb, which means they are largely stripped of much of their nutritional value.
They are found in the form of white bread or pasta and sugary sweets.
Unrefined carbs, on the other hand, are less processed and so have more nutritional value, as they are rich in vitamins, minerals and fibre.
They can be found in brown rice and pasta, wholemeal bread and fruits.
This is an important information to consider, as the energy contained in carbs can't be released into the body without vitamins and minerals (especially vitamin B) being present. Overconsumption of refined carbs is therefore not optimal, as they are mostly deprived of these vitamins and minerals.
In conclusion, carbohydrates are an essential source of energy for both our physical activities and brain function.
Low and high carb diets can be effective and meaningful depending on your level of activity and needs.
Simple healthy carbs are more suitable for when we need fast energy, and complex healthy carbs should be eaten to supply more lengthy physical needs.
Fibre complete the consumption of simple and complex carbs and the vitamins and minerals that compound carbs are essential to release the energy they contain into the human body and maximise its function.