What are carbohydrates?
Carbohydrates are natural substances that contain oxygen, hydrogen and carbon – we need these substances to ‘get up and go’.
Carbohydrates are the only fuel that the brain and red blood cells can use, and the main source of energy for our muscles.
We get our carbohydrates from starchy foods like bread, pasta, rice, cereals, biscuits and potato. Sugars – such as table sugar or the natural sugars in fruit – are also sources of carbohydrate. No matter what your carbohydrate source is, your body will use it for energy.
What is glycaemic index (GI)?
When we eat carbohydrates, our digestive system breaks them down into glucose. The glucose then travels in our blood to the cells of our body. Our cells use this glucose to produce energy.
Different carbohydrates are turned into glucose at different rates. This means that different carbohydrates – that is, different foods – cause blood glucose levels to go up and down at different rates.
The glycaemic index (GI) ranks foods on a scale from 0-100, based on what effect the food has on blood glucose levels:
- Foods with a high GI (70-100) cause a large and fast rise and fall in blood glucose.
- Foods with a low GI (0-55) cause a more steady and long-lasting rise and fall in blood glucose levels.
Here’s a diagram that shows the difference between low-GI and high-GI foods.
(Source: Professor Jennie Brand-Miller, University of Sydney)
High-GI foods are useful for a quick energy boost. Low-GI foods are broken down slowly for steady, long-lasting energy. Including more low-GI foods than high-GI foods throughout the day will help keep your child’s energy levels steady.
Foods and their GI
The following is a guide only to some foods and their GI values. Different brands of food can have different GI values, so it’s best to speak to a dietitian or check the label on the food. Many foods are now marked with the glycaemic index symbol. To qualify for the symbol, foods must be low GI and meet strict criteria for energy, fat, saturated fat, sodium, fibre and calcium content.
(GI of 55 or less)
(GI between 56 and 69)
(GI of 70 or more)
- Multigrain bread
- Plain muesli and muesli bars
- Most fruits and vegies (except watermelon and potatoes)
- Rice (basmati, arborio and long-grain)
- White and wholemeal bread
- Soft drink
- Jasmine rice
- Some breakfast cereals (for example, Corn Flakes®)
- Sport drinks
Benefits of low GI
Benefits of a low-GI diet include:
- longer-lasting energy, which can improve concentration levels at school and performance during sport
- the feeling of being full for longer, which can help with weight control
- a higher number of essential fatty acids in the blood.
Using GI to create a healthy family diet
Many low-GI foods can be found in a healthy diet. If you’re planning a low-GI diet for your family, you can think about what foods to include, as well as how much and how often to eat them during the day.
Making healthy food choices isn’t just about considering the GI value – healthy diets also include plenty of low-fat foods and high-fibre foods.
Getting a balance of high and low GI
The rapid rise and fall in blood sugar levels that comes from eating high-GI foods can leave your child with low blood sugar. One consequence of low blood sugar is that your child will then feel hungry, which might lead to overeating.
It’s OK to eat some higher-GI foods. The trick is to make sure each meal and snack also has low-GI food on offer. This way you can moderate the effects of high-GI foods. High-GI foods and low-GI foods combine in your body for a medium GI – they balance each other out.
When you’re choosing which carbohydrate foods to offer your family, it’s important to think about not just the GI rating, but how much you’re eating of the different kinds of food.
A big serving of a high-GI food, such as potato, will have a big impact on blood glucose levels. So you might consider including high-GI foods in smaller amounts, with larger serves of low-GI foods to get more of the benefits of low-GI foods.
When to eat your carbohydrates
To get the benefits of a low-GI diet, it’s worth thinking about when to eat your carbohydrates each day.
The ideal is to eat three regular meals (and possibly snacks), with an even spread of carbohydrates throughout the day. This will lead to more even blood glucose levels and provide fairly steady energy levels. This is essential for people with diabetes, but it’s also important for people who want to keep up good health.
Your child’s carbohydrate needs will depend on how much physical activity she gets and her age.
Making the change to low-GI diets
Switching to a low-GI diet is easy – chances are your family won’t even notice the difference.
By swapping at least half your carbohydrate food choices for lower-GI options, the whole family can reap the benefits.
|White or wholemeal bread
||Multigrain breads, pita bread, sourdough or low-GI white bread
|Processed breakfast cereals such as Rice Bubbles®, Corn Flakes® or Nutrigrain®
||Unrefined breakfast cereals such as porridge, or specific cereals with known GI, such as Guardian®, Special K® or Just Right®
|Plain biscuits and crackers
||Biscuits made with dried fruit and wholegrains
|Cakes and muffins
||Cakes and muffins made with fruit, oats and wholegrains
|Tropical fruits – for example, watermelon
||Cooler-climate fruits – for example, apples, stone fruit, citrus fruits
||Sweet potato, Carisma potato, corn, pasta or legumes such as lentils, beans and chickpeas
||Basmati, Doongara or Mahatma rice
Frequently asked questions about low-GI diets
What if my child doesn’t like low-GI foods?
Not all of your child’s food needs to be low GI. Low-GI and high-GI foods combine in your child’s body for a medium GI – they balance each other out.
Try to find out which low-GI foods your child’s happy with and make these the ones you have at home. Ideally, at least half of your child’s carbohydrate foods will come from the low-GI foods he enjoys.
Chocolate has a low-GI value. Does this make it a good food choice?
Many foods high in fat have a low-GI value – chocolate’s a good example of this. A low-GI diet doesn’t cancel out the problems of a high-fat diet. So you still need to keep foods such as chocolate for treats.
Does eating too much sugar cause diabetes?
There’s no link between eating sugar and developing diabetes. But eating too much sugar can lead to tooth cavities and weight problems.
What’s the best food for my child to eat before sport?
Carbohydrate foods are the best source of energy before sport. Low-GI foods – such as porridge, wholegrain toast or sandwiches, milkshakes, fruit smoothies or a banana – will give your child sustained energy on the day of the game. High-GI foods, such as sweet drinks, can be handy for instant energy immediately before or after heavy physical activity. This is because they give your child carbohydrates and fluids at the same time.