SummaryRead the full fact sheet
- Carbohydrates are essential for a healthy body and should not be removed from the diet.
- Carbohydrates are the body's preferred energy source. The Australian Dietary Guidelines recommend 45–65% of energy needs to come from carbohydrates.
- Choose better quality, wholegrain carbohydrates over refined carbohydrates.
- A very low-carbohydrate diet combined with very high protein intake is not recommended.
- Very low-carbohydrate diets tend not to lead to long-term weight loss.
Do we need carbohydrates in our diet?
Carbohydrate is also an important energy source during exercise. The digestive system breaks down carbohydrates into glucose and the secretes a hormone called insulin to help glucose move from blood into the cells.
Eating a potato, a bowl of pasta, or any type of carbohydrate-rich food won't automatically make you fatter. In fact, the Australian Dietary Guidelines recommend 45–65% of energy needs to come from carbohydrates.
Which foods contain carbohydrates?
Carbohydrates are found in a variety of foods, including:
- Legumes (or beans).
- Starchy vegetables (such as potatoes, sweet potato, beans, corn).
- Processed or refined foods (such as white bread, white rice, hot chips).
- Sugary sweets (such as biscuits, cakes and lollies).
Some carbohydrates are healthier than others. have a slower and flatter blood glucose response. They take longer to digest and can help us feel full. Lower GI foods are less refined (or processed) such as , legumes and fruit.
What is a low-carb diet?
Low-carbohydrate (low-carb) diets are popular because they are based on claims that carbohydrates cause weight gain.
Although there are different variations, essentially low-carb diets restrict carbohydrate foods and replace them with foods usually high in protein and fat to lose weight.
Typical foods eaten on a low-carbohydrate diet include – beef, chicken, bacon, fish, eggs, non-starchy vegetables, and fats (such as oils, butter and mayonnaise).
Foods that are restricted include – many types of fruit, bread, cereals and other grains, starchy vegetables and some dairy products (other than cheese, cream or butter).
Restricting certain foods can affect your weight
If you are on a low-carb diet, and cutting out large groups of vegetables, fruits and grains, you may not be getting enough vital nutrients to manage your weight effectively. These types of diets can increase your risk of micronutrient deficiencies and constipation because of their low fibre content.
- and alternatives (such as fish, eggs, soy and nuts and seeds).
- (like milk, yoghurt and cheese).
Risks of low-carb diets
Very low-carbohydrate diets are unlikely to meet your daily nutritional needs.
Advocates of these diets advise people to consume kilojoules mainly from protein and fat sources – often recommending eating less than 100g of carbohydrate each day.
Many health professionals do not support these diets as they can have a high fat content (particularly saturated fat) and restrict important nutrients.
Very low-carb diets tend to restrict healthy food choices and may be:
- High in .
- Nutritionally inadequate because they are low in thiamine, , vitamins A, E and , , magnesium, and potassium.
- Low in .
- Missing important and phytochemicals.
Short-term health effects of low-carb diets
Initially, low-carbohydrate diets may contribute to rapid weight loss because they restrict kilojoules or energy.
The body begins to use stores of glucose and glycogen (from the liver and muscles) to replace the carbohydrates it is not getting from food. Around 3g of water is needed to release 1g of glycogen. Any weight loss at the beginning of a low-carbohydrate diet is mostly water, not body fat.
As carbohydrate stores are used up, the body begins to rely on other sources of fuel such as fat. This can lead to the development of ketones in the body, which can make the body acidic. It can also contribute to , which may be dangerous for some with certain conditions (such as diabetes).
Symptoms that may be experienced from a low-carbohydrate diet, include:
Long-term health effects of low-carb diets
The long-term health effects of a diet very low in carbohydrates but high in saturated fat is still uncertain. Further research is needed to determine the safety of these diets.
Possible long-term effects may include:
- Weight gain – when a normal diet is resumed, some muscle tissue is rebuilt, water is restored, and weight quickly returns.
- Bowel problems – restricted intake of antioxidants and fibre from fruits and vegetables can increase a person’s risk of constipation.
- Dieting problems – such as the ‘yoyo’ effect (where people lose and regain weight many times over a long period, rather than sustaining weight loss).
- High , – diets high in protein and fats are associated with conditions, (such as , and ). This can occur if the you have a diet high in fat, especially from fatty and processed meats (such as salami, sausages and bacon).
- – can occur in people with impaired kidney function or diabetes.
- and related conditions – due to loss of calcium from the bones.
Healthy way to lose weight
high in fruits and vegetables, wholegrains, legumes and low-fat dairy products, and moderate in fat and kilojoules balanced with daily physical activity, is the best way to lose weight and keep it off.
are generally slimmer and have much lower rates of obesity, heart disease and cancer, than those who eat meat. This supports current thinking that diets high in unrefined carbohydrates help to maintain a healthy weight.
Watch your energy (kilojoule) intake
Avoiding large portion sizes and limiting intake of saturated fats and added sugars will help to keep your energy intake in check.
Regular exercise is also critical for long-term weight loss success.
If you are not sure where to start or finding it difficult to manage your weight, seek help from a dietitian. Dietitians can guide you to a healthy way of eating that is based on the latest research and tailored to suit your health and lifestyle.
What foods meet our nutritional needs?
For most adults, suggested daily serves may include:
|Recommended servings||One serve is equivalent to|
|4-6 serves of grain (mostly wholegrain) foods||• 1 slice of wholegrain bread|
• ½ cup of cooked porridge
• ½ a cup of cooked grains (such as pasta, brown rice, quinoa, polenta)
2 serves of fruit
• 1 apple, orange or banana
|5 serves (women) or 6 serves (most men) of vegetables.||• 1 cup of salad vegetables|
• ½ cup of cooked dried beans or legumes
• ½ a potato
• ½ cup of other cooked vegetables (broccoli, spinach, carrots)
|2½ serves of milk, yoghurt, cheese and alternatives||• 1 cup of milk|
• 2 slices (40g) of cheese
• 1 small tub (200g) of yoghurt
|2-3 serves of meat or meat alternatives||• 65g cooked lean beef, lamb, veal or pork|
• 80g cooked chicken
• 100g cooked fish
• 1 small can of fish
• 2 large eggs
• 1 cup of canned beans
• 170g tofu
• 30g nuts or seeds
Select carbohydrates, proteins and fats carefully
If you choose to follow a low-carbohydrate diet, do not avoid carbohydrates completely – you need some in your diet for fuel and to metabolise fat.
Choose carbohydrate-rich foods that are unrefined or unprocessed (including wholegrains and fruit), rather than refined and energy-dense forms (such as cakes, sweets and soft drinks). Have a variety of vegetables daily.
Select a variety of protein-rich foods that are also low in saturated fat, for example:
- Lean cuts of red meat.
- Fish (including fatty fish).
- Lean chicken and pork.
You could also select protein-rich foods that are plant based, for example:
Where to get help
- National Health and Medical Research Council, Australian Government
- , 2018, Australian National Health and Medical Research Council
- , Sports Dietitians Australia
- Cuenca-Sánchez M, Navas-Carrillo D, Orenes-Piñero E, 2015, ‘’, Advances in Nutrition, Volume 6, Issue 3, pp 260–266
- , The Nutrition Source, Harvard School of Public Health, USA
- Kirkpatrick, C., Bolick, J., Kris-Etherton, P., Sikand, G., Aspry, K., & Soffer, D. et al. (2019). ‘Review of current evidence and clinical recommendations on the effects of low-carbohydrate and very-low-carbohydrate (including ketogenic) diets for the management of body weight and other cardiometabolic risk factors: A scientific statement from the National Lipid Association Nutrition and Lifestyle Task Force’, Journal Of Clinical Lipidology, 13(5), 689-711
- Adam-Perrot A, Clifton P, Brouns F 2006, ‘, Obesity Review, vol. 7, pp. 49–58
- Nordmann AJ, Nordmann A, Briel M et.al. 2006, ‘, Archives of Internal Medicine, vol. 166, pp. 285–294. .