There’s a lot of noise around carbohydrates these days — high carb, low carb, no carb — and it can leave people wondering what actually matters when it comes to eating well. This month, our dietitian Linda Kilworth breaks it down in a practical, easy-to-understand way, looking at what carbohydrates do in the body and why the real answer is not about fear or extremes, but about understanding the role they play in everyday health.
Carbohydrates - often called “carbs” - have been getting a lot of attention lately. But what are they, and do we really need them?
Carbohydrates are one of the body’s three main nutrients (called macronutrients), along with protein and fat. They are the body’s primary source of energy, especially for the brain.
What foods contain carbohydrates?
Carbohydrates fall into three main types:
1. Simple carbohydrates (sugars)
These are found naturally in foods like fruit and milk, and are also added to many processed foods.
2. Complex carbohydrates (starches)
These are long chains of sugar molecules that the body breaks down into simple sugars during digestion. They are found in foods like bread, pasta, rice, grains, corn, potatoes, and sweet potatoes.
3. Dietary fibre
Fibre is found in plant foods. It helps keep your digestive system healthy but isn’t broken down into sugar like other carbs. Even though it doesn’t provide energy, it plays an important role in overall health.
Why does the body need carbohydrates?
Carbohydrates are the body’s main energy source. When you eat carbs, your body turns them into glucose (a type of sugar) for energy. Any extra glucose is stored in the liver and muscles for later use. If those stores are full, the excess is converted into fat.
If you don’t eat enough carbohydrates, your body has to find other ways to make energy. It may start breaking down muscle protein to produce glucose, which isn’t ideal.
Because of this, having some carbohydrates in your diet helps fuel the brain, maintain energy levels and prevent muscle loss.
What about “no carb” diets?
“No carb” diets are very restrictive and can be difficult to maintain. They often cut out entire food groups like fruits, vegetables, and grains, which can lead to an unbalanced diet.
These diets are extreme versions of ketogenic (keto) diets and can cause rapid weight loss at first. When you eat very few carbs, your body produces ketones, which come from breaking down fat. Ketones can be used as an alternative energy source when glucose is low. However, even in this state, the brain still needs some glucose. The body may still break down muscle to supply it, although ketones help reduce how much muscle is lost. This process is a survival mechanism that allows the body to function during starvation.
What about low-carb diets?
Low-carb diets include some carbohydrates (usually less than 30% of daily energy) and focus on whole foods and healthy fats.
These diets can support weight loss, reduce body fat, help manage blood sugar and be useful for people with type 2 diabetes
However, they may also be lower in fibre and will affect gut health due to the lower fibre and higher meat intake. These diets provide fewer vitamins and minerals (like magnesium, calcium, vitamin C, and some B vitamins). On the plus side, they may improve intake of nutrients like iron and vitamin B12.
What about high-carb diets?
High-carb diets provide 50% or more of daily energy from carbohydrates. These diets are usually rich in plant-based foods like whole grains, fruits, vegetables, and legumes. Because these foods are high in fibre, they also help you feel full and support healthy digestion.
They can provide a steady energy source, especially for those that are active and need endurance.
It’s important to note that healthy high carbohydrate diets encourages unprocessed carbohydrates- not refined or highly processed foods, which can contribute to weight gain and poor health.
So, what’s the solution?
It all depends on what your goals are. Generally , a balanced diet is looking at at least half the daily intake should contain carbohydrates. The real question isn’t whether carbs are “good” or “bad”—it’s about the type and amount of carbohydrates you eat.
Take-home points
• Carbohydrates are essential for many functions in the body
• They are the main source of energy for daily activities
• The brain relies heavily on carbohydrates for fuel
• If carbs are too low, the body uses other methods to produce energy, which may include breaking down muscle
• Eating moderate amounts of carbohydrate containing food supports healthy eating.
• Wholegrains, fruits, vegetables and legumes are important sources of complex carbohydrate and dietary fibre.
Linda