It's Monday afternoon and you've caught an official case of Mondayitis. Where did the weekend go, you wonder. You're feeling tired, worn out, maybe even a little brain dead. Deadlines have hit you like a ton of bricks. You check the time, it's only 3pm and the clock is ticking very slowly. What do you need? A sugar fix.
You reach for the communal lolly jar, grab some jelly beans, and wait for the sugar to rush into your blood to make you feel alive again. A few minutes later, you feel better. Good? Not good.
Because in about half an hour or so, that sugar high that you've just experienced is going to come crashing down, to a much lower level than you started on. You'll feel tired and exhausted again, although this time much more than you felt to begin with.
A little man named Insulin...
You see every time you give yourself a sugar hit, a hormone called insulin is released. Insulin's job is quite simple. As it's dangerous to have sugar in your blood for long periods of time, insulin moves this sugar from your blood and takes it out into the cells. Once it reaches the cells, it can be taken to a number of places where it can be used as energy. Insulin is like a key that unlocks a door for sugar to be moved from one place to another.
So every time you give yourself a sugar hit, mr insulin man comes running out to do his job. The problem is that the bigger the sugar hit, the more insulin men that need to come out. So those jelly beans that you use to cure your 3pm slump are actually going to mean an influx of insulin men.
If only insulin men looked like firemen...
The bigger the sugar hit, the bigger your fat stores
Now an influx of insulin men means that the body ends up burning carbohydrate stores, rather than fat stores. This is because insulin's role, other than being the key to the door to release sugar from the blood to the cells, is to put a big stop sign up against any fat burning. Yes, this means Mr Insulin trys his hardest to hold onto your body fat!
Ok so maybe mr insulin man isn't so nice after all. You can imagine what happens when 10 insulin men come out to fight the fire. The bottom line is you'll be less likely to lose weight, in fact, chances are you will gain weight.
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What's happening is that their sugar levels go from rock bottom to sky high, back to rock bottom and then sky high again, and so on. Imagine how their insulin men are feeling.. very worn out I would imagine. Their insulin men would be working hard all day long, the cells would be constantly forced to use sugar as their fuel source whilst in the meantime fat stores are slowly accumulating. Fat stores can accumulate in the muscles (a sign of insulin resistance), in the blood (called high triglycerides), in the liver (fatty liver) and around the waist (ie. a pot belly). Having constantly high insulin levels is not only going to lead to weight gain, but is also closely associated with risk factors for heart disease and type 2 diabetes.
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You have the control
The good news is that you have control over the efficiency of your insulin men. Like humans, if you overwork them (by consuming high sugar, high GI foods on a regular basis) they will become less and less productive, until they eventually crash and burn. Heard of people injecting insulin? In type 2 diabetes, injecting insulin is common as the insulin men have crashed and burned from being overworked. The body isn't making enough insulin so they need to get it from an external source.
So how can we maintain our sugar levels without the peaks and troughs and large insulin response? Is there a diet pill you can take to cure all of your problems and send you away on a romantic getaway with your fire.. ahem I mean insulin- men? No.
But there is an answer, it's called.....drum roll......
Glycaemic Index
Carbohydrates used to be classified as simple and complex. Now, thanks to lots of research, we have good evidence to classify carbohydrates according to their Glycaemic Index, or GI.
Very simply, the GI is a scale of 0 to 100 that ranks carbohydrates according to their effects on blood sugar levels. Low GI carbohydrates (0-55) are digested and absorbed slower in the body, meaning they produce gradual rises in blood sugar levels. Whereas high GI (70-100) carbs are rapidly digested and absorbed, meaning they result in fluctuating sugar levels, with upward and downward spikes. There are also moderate GI foods which fit in between (56-69). The example I gave earlier of the lolly jar is what happens when you eat high GI foods. You might get a quick sugar rush, but as they say, what goes up must come down.
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| High GI Low GI |
Source: The Low GI Diet: Lose Weight With Smart Carbs, 2006
How do you tell the difference?
A common question I get asked is how do I know which foods are high GI and which are low GI? Unfortunately there's no mathematical calculation or formula that can easily separate foods into the 3 categories.
There are however some basic principles which can lead us to understand why some foods have a low GI, while others have a high GI.
The properties that affect GI are:
1. The type of starch. For example, amylose found in kidney beans absorbs less water and thus is digested slower than the standard potato, which contains amylopectin and absorbs more water.
2. Physical barriers. Foods like wholegrain cereals that have an outside 'bran' barrier means it's harder for the body to break it down, thus the process is slower and the food has a lower GI. If you compare these to cereals like cornflakes or rice bubbles, by being highly refined they can be broken down much quicker, meaning the GI is higher.
3. Sugar type. As mentioned in my post, Is sugar the enemy? there are many different types of sugar. Some sugars such as glucose have a very high GI (100), while others such as fructose have a low GI (19). Table sugar or sucrose, is made up of glucose and fructose, giving it a GI of 60. So the type of sugar in a food can affect its GI.
4. Fat and protein content. Fat and protein slow gastric emptying, so foods containing fat or protein will have a lower GI. For example chocolate (high in fat) has a low GI. This is not to say that you should eat lots of chocolate, but simply to demonstrate how fat can affect GI.
5. Acid content. Foods containing acids will also have a lower GI as acids slow the rate of gastric emptying like fat and protein do. Adding a vinegar or lemon juice based dressing to a salad will lower its GI. This is also why sourdough bread has a lower GI than most other white breads.
6. Processing. Highly refined or processed foods generally have a higher GI as they have already been processed into a form that is easier to digest. For example, rolled oats have a low GI whilst quick oats (rolled oats that have been ground up into a more processed form) have a moderate GI.
7. Cooking. Cooking swells starch molecules and softens foods which increases the rate of digestion, increasing the GI value. This is why having al-dente spaghetti (GI 44) is better than having overcooked spaghetti (GI 64).
If you are wondering what the GI is of your favourite food, go to glycemicindex.com and search for your food under the GI database tab. Diabetes Australia has some excellent information on GI. You can also check out my table below to see where your favourite food sits.
Not all low GI foods are good for you
I was recently asked why Coke (GI 53) has a low GI. Going back to my comments earlier about the type of sugar and their GIs, Coke is made using cane sugar meaning it will have a lower GI than a product made with glucose. Does this make it a nutritious drink? No. It's important to keep in mind that not all food and drinks (eg. soft drink, chocolate, ice cream) with a low GI will be healthy choices.
Don't forget that quantities are also important. Whilst low GI foods will help to keep your blood sugar levels controlled, this rule goes out the window if you eat huge portions of them. So the rule is, choose healthy, low GI foods in sensible portions.
Take home message
Low GI foods have many health benefits. When it comes to main meals, aim to include a low GI carbohydrate at each meal. This will mean you will have the luxury of feeling fuller for longer, and you won't be reaching for that lolly jar at 3pm! It's perfectly normal to be feeling hungry after a couple of hours post-lunch, so if you do feel like an afternoon snack, go for something nutritious like a piece of fruit, a tub of yoghurt, low fat cheese and wholegrain crackers or a small handful of nuts.
FOOD | LOW GI (slow acting) | MODERATE GI | HIGH GI (fast acting) |
BREADS | Wholegrain / Multigrain breads Holsom’s® wholemeal Burgen® breads (except Burgen Oat Bran and Honey Bread®) PerforMAX® Vogels® Honey Oat Loaf Fruit loaf / Raisin bread Soy and linseed bread Pumpernickle Sourdough rye Soy and linseed bread | Rye bread Light rye bread Pita bread Hamburger bun Crumpets Croissants Ploughmans® wholemeal (smooth milled) Burgen® Oat Bran and Honey Bread | High fibre white breads e.g. Wonderwhite® White bread Wholemeal bread Dark rye bread English muffin (white) Bagels French baguette Gluten free white bread |
GRAINS AND CEREALS | Pearl Barley Cracked Wheat (Bulgur) Buckwheat Pasta e.g. Spaghetti, Macaroni, Vermicelli Noodles, Fettuccine Noodles, Instant Noodles, Soba Noodles Note: Fresh and dried pastas have a low GI – this is not the case for canned spaghetti. Doongara (Clever) Rice Wild rice Semolina | Basmati rice (Mahatma®) Long Grain Rice Couscous Taco Shells Aborio Rice Gnocchi Cornmeal | White rice Jasmine rice Tapioca Calrose rice Brown rice |
BREAKFAST CEREALS | All-Bran® All Bran Fruit and Oats® Bran Buds with Psyllium® Rolled Oats / Porridge Special K® Rice Bran Oat Bran Barley Bran Guardian® Komplete Muesli® Toasted Muesli Healthwise for Heart Health® Goodness Superfoods® cereals | Instant 1 minute Oats Just Right® Nutri-Grain® Sustain® Untoasted (Natural) Muesli Vita Brits® Weet‑Bix® / Vita brits® Sustain® Shredded Wheat Plain Mini Wheats® | Bran Flakes® Coco Pops® Corn Flakes® Puffed Wheat® Rice Bubbles® Sultana Bran® Breakfast Bars Mini Wheats® (fruit filled) Fibre Plus Breakfast Bar® |
MILK AND DAIRY FOODS | Milk – Full cream, Low fat, No fat, Flavoured, Soy, Almond Yoghurt – Plain, Flavoured, Regular, Low fat, Diet, Soy Drinking Yoghurt e.g. Yakult Ice Cream – Regular, Low fat, Diet Custard – Regular, Low fat, Diet | Oat Milk Vitari® | Rice Milk |
VEGETABLES | Legumes e.g. Baked beans, Lima beans, Chickpeas, Split peas, Haricot beans, Kidney beans, Lentils, Soy beans, Green Beans Sweet corn, Sweet potato, Carrots, Taro, Parsnip Carisma potatoes | New potatoes (canned only) Broad beans Pumpkin | Potato (baked, boiled, mashed) Instant potato French fries |
FRUIT | Apples Banana Cherries Grapefruit Grapes Kiwi fruit Mango Oranges Peaches (fresh/canned in juice or light syrup) Pears (fresh/ in juice) Plums Dried apricots Dried apple Unsweetened juice e.g. Apple, Grapefruit, Orange Prunes | Apricots (fresh/canned) Paw Paw Peaches (in syrup) Pineapple Rockmelon Raisins Sultanas Figs Mango | Watermelon Dates Lychee (canned) |
BISCUITS AND CAKES | Arnott’s® Jatz Westons® Highland Oatmeal Rich Tea Apple Muffin Banana Cake Sponge Cake Arnott’s® Snack Right Fruit Slice Arnott’s® Snack Right Fruit Pillow Vitawheat® | Arrowroot Biscuits Arnott’s® Milk Arrowroot Arnott’s® Shredded Wheatmeal Blueberry Muffin Bran Muffin Ryvita® Breton® wheat crackers Digestive biscuits Shortbread | Cruskits® Premium® Morning Coffee® Rice Cakes Corn Thins Kavli® Vanilla Wafers Water Crackers Sao® |
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Image: Michelle Meiklejohn / FreeDigitalPhotos.net
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