As a health-conscious person, GI is probably a term you’ve often heard thrown around in conversation or read in articles, but do you know what it is and why getting to grips with it could aid your weight loss? Here, we explain why you should stick to low GI foods for the good of both your health and your heart.
Glycemic Index (GI) is a system that ranks foods based on how quickly they affect blood glucose levels. The faster a food is broken down and the energy released into the body’s system, the higher its GI. It’s these foods that give you an energy high and then leave you feeling tired when the slump hits. Whereas low GI foods trickle glucose into your blood stream slowly, keeping your energy levels balanced.
Each food is given a GI ranking number between zero and 100 and depending on its vital digits it will fall into one of these categories:
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Low GI = 55 and under
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Medium GI = 56-69
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High GI = 70 and above
So the lower the number, the lower the GI and the better food choice, but why? And how will this affect your weight loss and health?
Weight loss
Low GI foods allow for a greater rate of fat oxidation following consumption, plus they provide greater satiety so you’re less likely to eat between meals and reduces the amount you eat at meals, all helping you with the weight-loss battle.
Whereas, when you consume high GI foods, the body produces more insulin. Joanna McMillan-Price from the University of Sydney Human Nutrition Unit explained, “Insulin is a storage hormone; the more there is the less fat tissue is released for fuel. Low GI foods lower the insulin demand, which helps promote fat for fuel.”
According to a study by the University of Sydney, lead by MacMillan herself, the most affective diet for weight loss and a healthy heart is a high-carbohydrate plan based on low GI foods.
In the first study of its kind, 129 overweight people aged between 18-40 were placed on one of four diets for 12 weeks. Of the two high-carb diets, the one with the lower GI doubled fat loss, with effects being greatest in women. It also saw a reduction in LDL or ‘bad’ cholesterol.
Speaking on these findings, MacMillan confirmed, “We found that moderate reductions in glycemic load appear to increase the rate of body fat loss, particularly in women.”
However, eating healthy, low GI foods doesn’t mean you can carb load until your heart’s content. Although MacMillan advised to pay particular attention to your portions when eating high GI foods, the same caution should be applied to low GI as too many carbs, no matter what their GI, can be detrimental to your weight-loss success, except of course for the old faithful veggies.
Health
Eating high GI foods also has other implications on your health. Due to the large amounts of insulin produced following the consumption of high GI foods, there’s an increased risk of type 2 diabetes. McMillan said, “Eating high GI all the time means your pancreas has to produce much more insulin than it is designed to do. Eventually it gets ‘tired’ and starts to produce ineffective and insufficient insulin,” which can lead to the onset of type 2 diabetes.
And it’s not just the pancreas that can be affected by high GI foods. The research also showed that a high blood glucose level lead to a high risk of heart disease as well. “Glucose spikes damage blood vessels, in particular smaller ones, as do high levels of insulin that occur with a high GI diet,” revealed McMillan. “GI has also been found to be related to the cholesterol levels in blood and weight control. This combination has a consequential impact on heart health.”
Knowing a food’s GI
Unfortunately GI isn’t as simple as; processed equals high GI, natural equals low GI. Even some naturally-grown products, such as fruit, are high GI but should be enjoyed aplenty. However, neither do you need to scrutinise over the exact GI number of every food you eat.
“GI is just the science explaining why wholesome, minimally-processed foods are better for us,” explained McMillan. “In general, if you avoid modern processed carbohydrates, you pretty much achieve a low GI diet, with a couple of exceptions, such as potatoes and brown rice.”
Thankfully, a nationally-recognised GI symbol has been created to help make choosing low GI foods quick and easy. To carry this symbol, the food must be a good source of carbohydrate, as well as match other nutrient criteria for calories, total and saturated fat, sodium, and where relevant fibre and calcium.
However, if a food claims to be low GI but does not feature the symbol, be cautious. A recent survey of Australian foods showed that many claims were false or inaccurate, or the food product was not a good nutritional choice, containing too many calories, saturated fat or salt.
As a general rule Macmillan advised, “The symbol is great for breads, cereals and other packaged foods, but for other items choose wholegrain (not wholemeal or multigrain), heavy grainy breads, sweet potatoes, corn, barley, quinoa, freekeh, bulgur wheat, whole fruit, legumes and plenty of vegetables.”
You can also search the GI of specific foods online at www.gisymbol.com.au/foods.htm.