Carbohydrates give our bodies around half the energy they need each day. Our bodies turn different carbohydrates into blood glucose at different rates. Glycaemic index (GI) is how we measure this. Balancing low-GI and high-GI foods can make family eating healthier.
What are carbohydrates?
Carbohydrates are natural substances that contain oxygen, hydrogen and carbon. We need these substances to give us energy – 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 carbohydrates from starchy foods like bread, pasta, rice, cereals, biscuits and potato. We also get carbohydrates from sugars such as table sugar, the natural sugars in fruit and dairy, and sugary foods such as desserts.
No matter what type of carbohydrate you eat, your body will use it for energy.
What is glycaemic index (GI)?
When we eat carbohydrates, our digestive system breaks them down into their simplest form – glucose. Our cells use glucose to produce energy.
Carbohydrates break down 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) measures the effect that carbohydrates in food have on blood glucose levels. GI ranks foods on a scale from 0-100:
- Foods with a high GI (70-100) cause a large and fast rise and fall in blood glucose. That’s because the carbohydrates in these foods break down quickly.
- Foods with a low GI (0-55) cause a more steady and long-lasting rise and fall in blood glucose levels. The carbohydrates in these foods take time to break down.
High-GI foods are useful for a quick energy boost. Low-GI foods are broken down slowly for steady, long-lasting energy. Eating more low-GI foods than high-GI foods throughout the day will help keep your child’s energy levels steady.
Foods and 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, but not all low GI foods, are now marked with the Glycemic Index Foundation’s Low-GI symbol.
Foods with the symbol must be low GI and meet strict standards for kilojoules, fat, saturated fat, sodium and, where appropriate, fibre and calcium.
Low-GI foods (GI of 55 or less)
Intermediate-GI foods (GI between 56 and 69)
High-GI foods (GI of 70 or more)
- Dense wholegrain bread
- Carisma potatoes
- Doongara rice
- Pearl couscous
- Traditional oats
- Natural muesli
- Most fruits and vegies (except melons and most potatoes)
- Wholemeal bread
- Rice (basmati, arborio and long grain)
- Soft drink
- Sweet biscuits and cakes
- White bread
- Jasmine rice
- Most breakfast cereals (for example, flaked corn and puffed rice)
- Sport drinks
- Most crackers and savoury snacks
- Hot chips/French fries
Benefits of low-GI food
Low-GI foods are good because they give you longer-lasting energy, which can help you concentrate better and keep going for longer if you’re doing physical activity.
If you do endurance sports such as long-distance running, low-GI foods help you keep up your energy levels.
Low-GI foods also keep you feeling fuller for longer, which can help you with maintaining a healthy weight.
Using GI to plan healthy family eating
It’s good to think about GI when you’re planning what your family will eat, as well as making sure that your family eats plenty of lower-fat, higher-fibre foods.
Getting a balance of high and low GI
Low-GI foods are generally better than high-GI foods. This is because high-GI foods make blood glucose (sugar) levels go up and down quickly, which can leave you feeling ‘hungry’. This can lead to overeating.
It’s OK to eat some high-GI foods occasionally. The trick is to have a low-GI choice for your family at each meal and snack.
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 foods to offer your family, it’s important to think about not just the GI rating, but how much of these foods you’re eating – that is, portion size.
A big serving of a high-GI food such as potatoes or chips will have a big impact on blood glucose levels. So if you have small serves of high-GI foods and larger, more frequent serves of low-GI foods, you can balance things out.
When to eat your carbohydrates
There’s no hard and fast rule about when to eat carbohydrates, but it’s good to have three regular meals and two snacks, so that you get an even spread of carbohydrates across the day.
This will lead to more even blood glucose levels and provide fairly steady energy levels. This is essential for adults and children with diabetes, but it’s also important for people who want to keep up good general health.
Your child’s total carbohydrate needs will depend on how much physical activity your child does and how old she is.
Making the change to low-GI foods
Switching to low-GI food is easy. Chances are your family won’t notice the difference – at least not all of the time.
By swapping at least half your carbohydrate food choices for lower-GI options, your whole family can reap the benefits.
For example, you can swap:
- white or wholemeal bread for multigrain breads, pita bread, or genuine sourdough bread
- processed breakfast cereals such as Rice Bubbles® or Corn Flakes® for unrefined breakfast cereals such as traditional (not instant) porridge, or cereals with low GI, such as All Bran®, Guardian®, Special K® or Sustain®
- plain biscuits and crackers for biscuits made with dried fruit and wholegrains
- cakes and muffins for cakes and muffins made with fruit, oats and wholegrains
- tropical fruits – for example, watermelon – for cooler-climate fruits such as apples, lady finger bananas, pears, peaches, grapes, nectarines, oranges and mandarines
- white potato for low-GI potatoes such as Carisma™, sweet potato, corn, pasta or legumes such as lentils, beans and chickpeas
- most rices for Basmati, Doongara or Mahatma rice.
Keeping skin on potato will increase fibre.
Frequently asked questions about low-GI foods
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 to give a medium GI – they balance each other out.
You can try to:
- keep lower-GI foods as ‘everyday’ foods and high-GI options as ‘sometimes’ foods
- find out which low-GI foods your child is 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 lower-GI value – chocolate is a good example of this. Low GI doesn’t cancel out the problems of high fat – you need to look at the whole food.
So you and your family should try to have foods such as chocolate as occasional treats only.
Does eating too much sugar cause diabetes?
There’s no link between eating sugar and developing diabetes. But eating too much added sugar can contribute to weight gain, and being overweight increases the risk of developing type-2 diabetes.
Eating too much added sugar can also lead to tooth cavities.
What’s the best food for my child to eat before sport?
Carbohydrate foods are the best source of energy before sport. Low-GI breakfast foods – such as traditional porridge, wholegrain cereal or toast, or fresh fruit smoothies – will give your child sustained energy on the day of the game.
GI and diabetes
If you have type-2 diabetes or impaired glucose tolerance, your blood glucose levels might rise above a normal level more quickly than other people’s.
Eating low-GI foods can help you manage your blood glucose levels. And eating moderate amounts of low-GI foods regularly over the day will help you keep consistent blood glucose levels.
If you have a medical condition such as diabetes, it’s important to talk with your GP, dietitian or specialist before making any changes to your eating.