"Carbs" has become a dirty word in recent times, especially in the weight loss world, due in no small part to the popularity of low-carb diets such as the Atkins, Dukan and South Beach.
The "carbs are bad" mantra from Dr Atkins and co has left many people confused about carbohydrates and their importance for your health, including maintaining a healthy weight.
Dietitian Sian Porter says: "Carbohydrates are such a broad category and people need to know that not all carbs are bad.
"While we should reduce the amount of sugar in our diet there is strong evidence that starch and fibre are good for our health.”
Find out all you need to know about carbohydrates, their health benefits, healthier sources of carbs and how carbs can actually help you lose weight.
What are carbs?
Carbohydrates are a major source of energy. When eaten, the body converts most carbohydrates into glucose (sugar), which is used to fuel cells such as those of the brain and muscles.
Carbohydrates are not a food group like fruit, vegetables and dairy foods. Carbohydrates are one of three macronutrients (nutrients required in large amounts) found in food – the others being fat and protein. Lots of foods contain all three in varying amounts.
There are three different types of carbohydrate: sugar, starch and fibre. Most carbohydrate foods contain a mixture of all three types in varying amounts.
- Sugar is found naturally in some foods, including fruit, fruit juices, milk (lactose) and vegetables. Other forms of sugar (for example table sugar) are also added to processed foods and drinks such as sweets, chocolates, biscuits and soft drinks. Remember: sugar is a carb but not all carbs are sugars.
- Starch, made up of many sugar units bonded together, is found in foods that come from plants. Starchy foods provide a slow and steady release of energy throughout the day. Find out more about starchy foods.
- Fibre is only found in foods that come from plants. Fibre helps keep our bowels healthy and some types of fibre may help lower cholesterol. Good sources of fibre include vegetables with skins on, wholegrain bread, wholewheat pasta and pulses (beans and lentils). Find out more about fibre.
Why do we need carbs?
Carbs are important to your health for a number of reasons. In a healthy balanced diet they are the body’s main source of energy. High fibre, slow release carbs help regulate sugar levels in the blood.
Energy
Carbs should be the body’s main source of energy in a healthy balanced diet, providing 3.75kcal (16kJ) per gram. Whether you eat starchy foods or sugary foods, both are broken down into glucose (sugar) before being absorbed into the bloodstream. From there, the glucose enters the body’s cells with the help of insulin. Glucose is used by your body for energy, fuelling all of your activities, whether going for a run or breathing. Unused glucose can be converted to glycogen found in the liver and muscles. If unused, glucose can be converted to fat, for long-term storage.
Disease risk
Vegetables, pulses, wholegrain varieties of starchy foods, and potatoes eaten with their skins on are good sources of fibre. Fibre is an important part of a healthy balanced diet. It can promote good bowel health, reduce the risk of constipation, and some forms of fibre have been shown to reduce cholesterol levels. Many people don't get enough fibre. On average, most people in the UK get about 14g of fibre a day. We are advised to eat an average of 18g a day.
Weight reduction
Starchy foods are low in calories and can be a good source of fibre, which means they can be a useful part of a weight loss plan. “The fibre physically fills you up and takes longer to digest, meaning you feel fuller for longer,” says Sian. "Just watch out for the added fats used when you cook and serve them: this is what increases the calorie content."
Don’t protein and fat provide energy?
While carbs, fat and protein are all sources of energy in the diet, the amount of energy that each one provides varies:
• carbohydrate provides: 3.75kcal (16kJ) per gram
• protein provides: 4kcal (17kJ) per gram
• fat provides: 9kcal (37kJ) per gram
If you consume more calories than you burn from whatever source, carbs, protein or fat, you will gain weight. So cutting out carbs or fat does not necessarily mean cutting out calories if you are replacing them with other foods containing the same amount of calories.
How can I increase my fibre intake?
To increase the amount of fibre in your diet, go for wholegrain varieties of starchy foods and eat potatoes with skins on. Try to aim for an average intake of 18g of fibre a day. Here are some examples of the typical fibre content in some common foods:
- two breakfast wheat biscuits (approx. 37.5g) – 3.9g of fibre
- one slice of wholemeal bread – 1.8g (one slice of white bread – 0.7g)
- 230g serving of wholewheat pasta – 8.1g (230g of white pasta – 2.8g)
- One medium (180g) baked potato (with skin) – 2.5g
- 200g of baked beans – 7.6g
- 1 orange – 2.7g
- 1 banana – 0.8g
How much carbohydrate should I eat?
The Government’s healthy eating advice, illustrated by the
eatwell plate, advises that a third of your diet should be made up of starchy foods, such as bread, rice, potatoes and pasta, and another third should be fruit and vegetables. Data from the National Diet and Nutrition Survey, which looks at food consumption in the UK, shows that most of us should also be eating more fibre and starchy foods and fewer sweets, chocolates, biscuits, pastries and cakes. Try to aim for at least
five portions of a variety of fruit and veg a day. Go for wholegrain starchy foods whenever you can and eat potatoes with their skins
on.
What carbs should I be eating?
Sweets, chocolates, biscuits, cakes and soft drinks with added sugar are usually high in sugar and calories, which can increase the risk of tooth decay and contribute to weight gain if you eat them too often, while providing few other nutrients.
Fruit, vegetables, pulses and starchy foods (especially wholegrain varieties) provide a wider range of nutrients (such as vitamins and minerals) which can benefit your health. The fibre in these foods can help to keep your bowels healthy and can help you feel full for longer, which means we're less likely to overeat.
Sian says: “Cutting out a whole food group (such as starchy foods) as some diets recommend could put your health at risk because as well as cutting out the body’s main source of energy you’d be cutting back essential nutrients like B vitamins, zinc and iron from your diet.”
Can eating low GI (glycaemic index) foods help me lose weight?
The glycaemic index (GI) is a rating system for foods containing carbohydrates. It shows how quickly each food affects glucose (sugar) levels in your blood when that food is eaten on its own. Some low GI foods, such as wholegrain foods, fruit, vegetables, beans and lentils are foods we should eat as part of a healthy balanced diet. However, using GI to decide whether foods or a combination of foods are healthy or can help with weight reduction can be misleading.
Although low GI foods cause blood sugar levels to rise and fall slowly and therefore may help you to feel fuller for longer, not all low GI foods are healthy. For example, watermelon and parsnips are high GI foods, while chocolate cake has a lower GI value. Therefore, relying on GI alone is not a reliable way to decide whether foods or combinations of foods are healthy or will help you to lose weight.
Do carbs make you fat?
If Dr Atkins has instilled one message into our weight-conscious minds, it is that carbs are fattening. Any food can be fattening if you overeat. It doesn't seem to matter a whole lot whether your diet is high in fat or carbs, but how much you eat in total. In fact, gram for gram, starchy foods contain fewer than half the calories of fat. Wholegrain varieties of starchy foods and potatoes eaten with their skins on are good sources of fibre. Fibre can help you to feel full, which means you're less likely to overeat and put on weight. However, foods high in sugar are often high in calories and eating these foods too often can contribute to you becoming overweight.
“When people cut out carbs and lose weight, it’s not just carbs they’re cutting out, they’re cutting out the high-calorie ingredients mixed in or eaten with it such as butter, cheese, cream, sugar and oil,” says Sian. "Eating too many calories – whether they are carbs, protein or fat – will contribute to weight gain.”
To maintain a healthy weight, we are advised to cut down on sugary foods in favour of fruit, vegetables, pulses, wholegrain starchy foods and potatoes with skins on, while still keeping a watchful eye on portion size.
Are carbs bad for our health?
Wheat and grains in general are the latest scourge of the health world. Grains, including wholegrains, have been blamed for a multiplicity of ills from dandruff, diabetes and dementia, to arthritis, schizophrenia and obesity.
A new market has sprung up on the back of the "wheat-is-evil" trend, including expensive gluten-free products and a wide range of grain and gluten-free diets. However, unless you have a diagnosed health condition such as wheat allergy, wheat sensitivity or
coeliac disease, the evidence for cutting out wheat and other grains from your diet is very weak. Grains, especially wholegrains, are an important part of a healthy balanced diet. All types of grains provide carbs, vitamins and minerals. Grains are also naturally low in
fat.
Can we survive without carbs?
While we can most certainly survive without sugar, it would be quite difficult to eliminate carbs entirely from your diet. Carbs are the body's main source of energy. In the absence of carbs, your body will use protein and fat for energy.
However, cutting out starchy foods from your diet could put you at increased risk of deficiency of certain nutrients leading to health problems (see above), unless you're able to make up for the nutritional shortfall with healthy substitutes.
It may also be hard to get enough fibre which is important for a healthy digestive system and to prevent constipation. Healthy sources of carbs such as starchy foods, vegetables, fruits, legumes and dairy products are an important source of nutrients such as calcium, iron and B vitamins.
Cutting out carbohydrates and replacing those calories with fats and higher fat sources of protein could increase your intake of saturated fat, which can raise your cholesterol which is a risk factor for heart disease.
Try to limit the amount of sugary foods you eat and instead include healthier sources of carbs in your diet such as wholegrains, vegetables, fruits, legumes and lower fat dairy products. Read
the British Dietetic Association's review of low-carb diets, including the paleo, Dukan, Atkins, and South Beach diets.
What’s the role of carbs in exercise?
Carbs, fat and protein all provide energy, but exercising muscles rely on carbohydrates as their main source of fuel. However, muscles have limited carb stores (glycogen) and they need to be topped up regularly to keep your energy up. A diet low in carbs can lead to a lack of energy during exercise, early fatigue and delayed recovery. Fat and protein are harder to turn into energy than carbs, which means you may feel low on energy during your exercise session.
