What are carbohydrates?

Reviewed by our clinical team

Carbohydrates (carbs) are an important part of a healthy diet. They are a type of macronutrient that our body needs to function properly. Macronutrients are the nutrients we need in the biggest quantities, micronutrients are needed in smaller quantities. 

In this guide we'll look at what carbohydrates do, why we need them and the best ways to get carbs into your diet in the right quantities. 

Why do we need carbohydrates?

Foods that contain carbohydrate provide us with energy, vitamins, minerals and fibre, which are all key to a healthy diet. 

Your body breaks carbohydrates down into glucose, which is then absorbed by the bloodstream and used as energy to fuel your body.

Sources of carbohydrates

Carbohydrates are found in a variety of food, some which are healthy and some which are less healthy. It's important to try and eat the right type of carbohydrate and in the correct quantities.

There are three types of carbohydrates:

• Starches
• Sugars
• Fibre

These types of carbohydrate are categorised as simple or complex. Complex carbohydrates take longer to breakdown/digest than simple carbohydrates. 

In the UK most of us will already be eating enough carbohydrates, but potentially the wrong type. For example, lots of people will be having too much sugar but not enough wholegrain starchy foods or fibre. 

Starches

Starches are complex carbohydrates. They should be our main source of carbohydrate and play an important role in a healthy diet. 

Examples of starches

• Bread
• Rice
• Potatoes
• Root vegetables

Healthiest starchy foods

Less processed starchy foods tend to be better for you because they contain more fibre. It takes the body longer to digest fibre, so the body breaks the carbohydrate down into glucose more slowly. This means your blood sugar remains stable and you feel fuller for longer. 

Examples of healthy starchy foods include:

• Wholegrain rice, bread and pasta
• Rye
• Barley
• Oats
• Millets

These starchy foods are also a key source of vitamins and minerals. 

Studies have found that fibre from wholegrains is linked with reduced risk of heart disease, type 2 diabetes, bowel cancer and inflammation.

Starchy foods to cut down on

There are some starchy foods that are considered 'unhealthy' and you should minimise your intake of these. They're considered unhealthy because they're refined. This means that when they're processed the part of the grain that contains fibre and other important nutrients is removed to make them appear whiter. The lack of fibre means they're they are digested quickly, and this leads to rapid spikes in blood sugar. 

Examples of refined starchy foods include: white bread, pasta and rice. 

How to include healthy starchy foods in your diet

• Swap 'white' versions of starchy foods for wholegrain versions and higher fibre foods:
  
  • Opt for wholegrain cereals, or mix some in with your favourite breakfast cereals
  • Try brown rice to make tastier rice salads
  • Try different varieties of bread such as seeded, wholemeal or granary bread
• Instead of having chips or fried potatoes, try making oven-baked potatoes or potato wedges - eat the potatoes with skin on for more fibre
• Add fruit and low-sugar yoghurt to whole oats to make it a healthy and tasty breakfast

Eating starchy foods in the right quantities

Although starchy foods are an important source of fibre and other vitamins and minerals, we should also be mindful that they contain four kilocalories (kcal) per gram.

Weight gain typically happens when you eat more calories than your body uses. It's important to get the right balance of foods for a healthy diet. 

Instead of completely cutting down on starchy carbohydrates, you can achieve a healthier diet overall by eating the right amount (about three or four portions of starchy foods in a day) and cutting down on refined carbohydrates and eating more fibre-rich foods. 

It's recommended that starchy carbohydrates should make up a third of the food you eat. 

Sugars

Sugars are a type of simple carbohydrate. Your body can break these down quickly, so they can cause a sharp rise and fall in blood sugar levels. That's why after eating sugary foods, many people experience a burst of energy followed by feeling tired.

Types of sugars

There are two main types of sugars - naturally occurring sugars and free sugars. 

Naturally occurring sugars

These sugars are found in whole fruits, vegetables and milk. These foods also tend to provide vitamins, minerals and sometimes fibre.

Free sugars

Free sugars are either naturally in things like honey, syrups, coconut sugar and fruit juice, or they're added to things like chocolates, sweets, cakes, biscuits, ice cream and fizzy drinks. 

These sugary foods and drinks are usually packed with lots of calories but don't have vitamins, minerals or fibre. 

How your body processes sugars

Unfortunately, your body processes all sugars in the same way. Too much of any type of sugar is associated with poor dental health, weight gain and chronic disease.

Current guidelines advise limiting you free sugar intake. It's recommended that adults consume no more than 30g (seven teaspoons) of free sugar a day.

Reducing your free sugar intake

Some tips for reducing the amount of free sugar in your diet include:

• Have a whole fruit rather than a fruit juice - eating an apple with skin on, will provide more fibre than drinking a glass of apple juice
• Avoid processed foods like biscuits, cakes, crisps, and sweets as they're high in calories and in low nutrition.
• Try more nutritious snacks like nuts, seeds and pulses
• Avoid sugar-sweetened drinks like fizzy drinks and fruit juices
• Always check food labels carefully and look out for foods and drinks with the green traffic light for sugar

Fibre

Fibre is a type of carbohydrate that you body can't digest easily. But fibre is important as it keeps our digestive system healthy, regulates blood sugar and lowers cholesterol. Choosing foods rich in fibre will keep you full for longer and make you less likely to overeat. 

Research shows that eating a fibre-rich diet decreases the risk of heart disease, type 2 diabetes and bowel cancer.

Sources of fibre

Fibre naturally occurs in plant-based foods like:

• Fruits and vegetables
• Nuts
• Seeds
• Pulses
• Beans
• Wholegrain products. 

Animal products, including dairy products and meats, have no fibre.

The right amount of fibre

The NHS recommends that you consume up to 30 grams of fibre per day as part of a balanced diet. But most of us eat about 20g a day. 

It's important to get fibre from a variety of sources as it improves the diversity of your gut bacteria which supports your immune system against inflammatory conditions and allergies.

Increasing your fibre intake

There are a number of ways you can increase your fibre intake, these include:

• Choose a higher-fibre breakfast cereal such as plain whole wheat biscuits (like Weetabix) or plain shredded wholegrain (like Shredded wheat), or porridge
• Go for wholemeal or granary breads. 
• Choose whole wheat pasta, brown rice or bulgur wheat
• Eat potatoes with their skins on, such as a baked potato or boiled new potatoes
• Include plenty of vegetables with meals, either as a side dish or added to sauces, stews or curries
• Add more pulses and beans to stews, curries and salads as they're lower in fat and higher in fibre and protein
• For snacks, try fresh fruit, vegetable sticks, rye crackers, oatcakes and unsalted nuts or seeds.

Fibre is important for keeping our bodies healthy and most of us don't eat enough. Instead of cutting down on carbohydrates, you can achieve a healthier diet by cutting down on sugary foods and eating more fibre-rich foods.

You can find out more about eating a healthy diet with this guide, or visiting our lifestyle advice hub. 

References

https://www.diabetes.co.uk/nutrition/simple-carbs-vs-complex-carbs.html
https://www.diabetes.org.uk/guide-to-diabetes/enjoy-food/carbohydrates-and-diabetes
https://www.nhs.uk/live-well/eat-well/food-types/starchy-foods-and-carbohydrates/
https://www.nhs.uk/live-well/eat-well/food-types/how-does-sugar-in-our-diet-affect-our-health/
https://www.nhs.uk/live-well/eat-well/digestive-health/how-to-get-more-fibre-into-your-diet/
https://www.bda.uk.com/resource/carbohydrates.html
https://my.clevelandclinic.org/health/articles/15416-carbohydrates
https://www.nutrition.org.uk/healthy-sustainable-diets/starchy-foods-sugar-and-fibre/starchy-foods/?level=Consumer
https://www.hsph.harvard.edu/nutritionsource/carbohydrates/