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Glycemic Index

Eating low-GI foods will help maintain your energy levels throughout the day and has some other great health benefits too.

sliced rye bread

What is Glycemic Index?

Every time we eat a carbohydrate food, such as pasta, potatoes, yogurt, cereal or fruit, our bodies convert carbohydrate to glucose for energy. Once upon a time we thought all carbohydrate foods were the same. We now know there is a difference in how quickly they are digested by the body. The Glycemic Index (GI) is a measure of how quickly these carbohydrate-rich foods are broken down into glucose and raise our blood glucose levels. Foods are ranked out of 100, with slowly digested carbohydrates classified as low GI (55 or less) and quickly digested carbohydrates as high GI (70 or more)1. woman taking blood sample

Benefits of eating the low-GI way

Eating high-GI foods can lead to energy ups and downs as the glucose reaches your bloodstream quickly (i.e. the sugar hit), but it doesn’t last for long. You could find yourself reaching for more snacks to bump up your energy levels again. Low-GI foods give you more steady energy levels across the day, helping to avoid the ‘slump’. With more constant energy levels, you may find you aren’t as hungry4.“In fact, there is very strong evidence that healthy low-GI diets are the most effective way of losing body weight, and more importantly, body fat,5???says dietitian and author Alan Barclay.“There is growing evidence that low-GI diets can help prevent type 2 diabetes6, heart disease7 and certain cancers,8???he says. woman in big jeans weight loss

How can I tell the GI of a food?

Not all carbohydrate foods have their GI measured. Foods that carry the GI logo have been tested and meet the criteria set out by the GI Symbol team. So lookout for the GI logo in the supermarket.

How can I lower the GI of my diet?

Getting the benefits from low-GI eating is easy! Simply swap some of your carbohydrate foods for low-GI choices using the examples in the table on page 2. An easy way to lower the GI of your diet is to include one low-GI food at each meal and snack –for example, adding a low-GI food like baked beans to a high-GI food like potato will help to reduce the overall GI of the meal. It is important to remember that portion size counts. Just because it’s low-GI, doesn’t mean you can eat as much as you like. Eating too many kilojoules, even if they are from low GI carbohydrates, can still lead to weight gain. diabetes superfoods

Aren’t all carbs bad for me?

There are plenty of myths out there about carbohydrates. The most common one is that carbohydrates are fattening. Protein, fat and carbohydrates all contain kilojoules, and if you eat too much of any of them without burning the energy, you can gain weight. Carbohydrates are actually the preferred energy source for your brain and working muscles, plus they have half the energy of fat. So include plenty of good-quality carbs in your diet like wholegrain breads and cereals, fruit and reduced-fat dairy, but remember to watch your overall kilojoule intake as well. magnifying glass

GI mini-quiz

How much do you know about GI? Take our quick quiz to find out then see below to see how you did.

Q1: All low-GI foods are healthy.

True or false?

Q2: Is the GI of chicken:

a) Low b) Medium c) High d) None of the above?

Q3: One of the benefits of a low-GI eating plan is:

a) It is lower in carbohydrates b) It helps manage blood-glucose levels c) It means you don’t have to count calories breads and flour

Answers to GI mini-quiz

1: False. Some foods that have a low GI, may be high in fat or salt. Therefore GI is not always an indicator of a healthier food choice. When it comes to healthy eating, the kilojoule (or calorie), fat, saturated fat and sodium content of a food need to be considered. Your choices should not be solely based on GI but also on recommendations to reduce saturated fat and increase fruit, vegetables and fibre3. 2: d) GI can only be measured in food containing carbohydrates. Chicken contains protein and fat, but not much carbohydrate, therefore it does not have a GI ranking. 3: b) Low-GI foods release glucose gradually into the bloodstream helping to manage blood glucose levels. Low-GI foods are carbohydrate foods, but they are not lower in carbohydrate than high-GI foods. Low-GI foods can have just as many kilojoules as high-GI foods, so just because it’s low-GI, doesn’t mean you can eat as much as you like. The overall kilojoules in your diet are still important to keep track of.

The following table show different foods that are high, medium and low GI2.

FOOD

LOW GI (FI 55 OR LESS)

MEDIUM GI (FI 55-69)

HIGH GI (FI 70 OR MORE)

Bread multigrain, low-GI white and sourdough bread pita and rye breads white/wholemeal bread, crumpets, English muffins, pikelets
Grains Pasta pasta, barley, noodles, Moolgiri rice Doongara and Basmati rice Calrose and jasmine rice, rice cakes, water crackers
Cereals natural muesli, rolled oats, bran-based breakfast cereals   most breakfast cereals like puffed rice, corn and wheat flakes
Vegetables corn, carrots, lentils, chick peas, kidney beans, baked beans beetroot, sweet potato, Nicola potatoes potato, parsnip
Fruit apples, oranges, strawberries, mangoes, pears, peaches apricots, pineapple, kiwifruit, bananas watermelon
Dairy milk, yogurt, ice cream, custard    
Sweet Treats chocolate soft drinks lollies, cup cakes, lamingtons

References:

1. Measuring the GI. Home of the GlycaemicIndex http://www.glycemicindex.com/ 2. Diabetes Australia. Fact Sheets: The glycaemicindex August 2006 http://www.diabetesaustralia.com.au/_lib/doc_pdf/resources/factsheets/GLYCAEMIC_INDEX_revised_Aug_06.pdf 3. Australian Government Department of Health and Ageing. Australian Guide to Healthy Eating http://www.health.gov.au/internet/wcms/Publishing.nsf/Content/health-pubhlth-strateg-food-guide-index.htm 4. Ludwig DS. 2000 Dietary glycemicindex and obesity. J Nutr130: 280S-283 5. Thomas DE, Elliott EJ, BaurL. Low glycaemicindex or low glycaemicload diets for overweight and obesity.Cochrane Database SystRev. 2007 Jul 18;(3):CD005105. 6. Barclay AW, Flood VM, RochtchinaE, Mitchell P, and Brand-Miller JC. GlycemicIndex, Dietary Fiber, and Riskof Type 2 Diabetes in a Cohort of Older Australians. Diabetes Care. 2007; 30(11): 2811-2813. 7. BeulensJW, de BruijneLM, StolkRP, PeetersPH, Bots ML, GrobbeeDE & van derSchouwYT (2007)High dietary glycemicload and glycemicindex increase risk of cardiovascular disease among middle-agedwomen: a population-based follow-up study. J Am CollCardiol50, 14-21. 8. Higginbotham S, Zhang ZF, Lee IM et al. Dietary glycemicload and risk of colorectal cancer in the Women’sHealth Study. J NatlCancer Inst 2004;96:229-33.©®of GI Symbol, The University of Sydney, used under licence.