Healthy eating habits/The Truth Behind Carbohydrates

This page was written as an education resource for Australian women aged 19-50 years.

Carbohydrates are a type of macronutrient; ‘macro’ meaning that it makes up the bulk of what we eat and ‘nutrient’ is a part of food which is used by the body for growth, maintenance and repair. However the carbohydrates found in different foods are not all the same. The two main types include the simple carbohydrates (sugars) and complex carbohydrates (starches and fibre). They differ in their chemical structure which affects how they are processed in the body.

When we eat carbohydrate containing foods, our body breaks it down into sugars called glucose which acts like a fuel to make energy. Certain parts of the body, such as the brain, can only use glucose as its energy source. This is why carbohydrates are needed in a healthy diet.

Most of the carbohydrates we eat come from plant sources, besides the sugars found in milk and small amounts of carbohydrates found in meat.

Complex carbohydrates are found in foods such as:

• Bread
• Cereals
• Pasta
• Rice
• Oats
• Quinoa
• Vegetables
• Fruit
• Legumes (beans, peas, lentils)

Simple carbohydrates are found naturally in nutritious foods such as:

• Milk
• Fruit

However, they are also found in many ‘sometimes’ foods such as:

• Confectionary
• Biscuits
• Cakes/Muffins
• Pastries

Weight gain occurs only when energy in (from foods and beverages) exceeds energy out (from resting metabolic rate and physical activity). Therefore, eating carbohydrate foods such as bread and pasta in a diet that is balanced in food energy will not cause weight gain.

Foods such as whole grains, vegetables and legumes are rich in complex carbohydrates (starches and fibres), which are digested and assimilated slowly because of their intricate chemical structures. The complex carbohydrates in foods such as whole grains, beans, and peas contain hundreds to thousands of glucose units (compared to just 2 sugar units for simple sugars such as sucrose), and they take longer to break down in the gut, hence promoting satiety. Research shows that diets high in whole grains may be protective against the development of obesity, type 2 diabetes, and hypertension thanks to their high content of slowly absorbable complex carbohydrates and magnesium. Indeed, many starchy foods (e.g., beans, whole-wheat pasta, oatmeal, potatoes) rank very high on the satiety index, are low in fat, and are surprisingly filling for their energy content thanks to their high moisture content. Choosing these foods can help with weight management by making you feel fuller for longer as well as reduce the risk of diseases, such as heart disease.

However, certain carbohydrate foods such as biscuits, muffins and cakes, if consumed regularly, may cause weight gain as they are high in energy (kilojoules) and dietary fats. These foods are highly palatable and less satiating, which makes it easier to overconsume dietary energy.

In a healthy diet, carbohydrates should contribute to 45-65% of our total energy intake. This is more than fat and protein.

The Australian Guide to Healthy Eating shows how much of each food group we should be having in our diets. The grain (cereal) and vegetables food group, which are high in carbohydrates, should be eaten more in our diet compared to the other food groups.

The table below shows the recommended daily number of serves for grain (cereals), vegetable and fruit food groups, for women aged 19-50 years. For information relating to the other food groups, visit the Australian Dietary Guidelines. The table also shows the average carbohydrate and dietary fibre in grams, per serve. It is recommended to have 30g of fibre per day as it is good for your health, such as lowering cholesterol and risk of constipation. This amount recommended is achievable if you eat plenty of grains, vegetables and fruit.

By reading the product’s nutrition information panel, this will show you if the food product is low in sugar or a good source of dietary fibre.

• A low sugar food product is considered to have no more than 5g of sugar per 100g of solid food.

• A good source of dietary fibre product has more than 4g of dietary fibre per serve. An excellent source has greater than 7g of dietary fibre per serve.

These tips can help you make better food choices next time you are at the supermarket.

For more information about nutrition information panels, visit the Food Standards Code. This website has information about general food standards (such as labelling of ingredients), food product standards, food safety as well as primary production standards used in Australia and New Zealand.

Food Standards Australia New Zealand (FSANZ). (2013). Standard 1.2.7 – Nutrition, Health and Related Claims. Retrieved from http://www.comlaw.gov.au/Details/F2013L00054

Marieb, E.N., & Hoehn, K. (Ed.). (2010). Human Anatomy & Physiology – Eighth Edition. San Francisco, California: Pearson Benjamin Cummings

National Health and Medical Research Council (NHMRC) – Australian Government. (2013). Eat for health – Australian Dietary Guidelines Summary. Retrieved from https://www.nhmrc.gov.au/_files_nhmrc/publications/attachments/n55a_australian_dietary_guidelines_summary_131014.pdf

Whitney, E., Rolfes, S.R., Crowe, T., Cameron-Smith, D., & Walsh, A. (2011). Understanding Nutrition: Australian and New Zealand Edition. South Melbourne, Australia: Cengage Learning Australia.