The Nutritional Institute

GO MULTI MAGAZINE - SEPTEMBER 2013

What does Low GI actually mean and is it a health-supporting strategy? Nutritional therapist Ian Craig has the answers. 

Around 10 years ago, while personal training in London, I came across this concept of Glycaemic Index (GI) via a French author Michel Montignac - it was barely known about back then and it certainly hadn't been popularised. Now, 1001 books have been written on the subject and it's very easy to fill your shopping trolley with products claiming to be Low GI. 

Like many concepts in nutrition, Glycaemic Index has been simplified and then simplified some more until we've forgotten what the original health intention was. I would therefore like to pose the provocative questions of what does Low GI actually mean and is it actually a health-supporting strategy?

What does Low GI Mean? 

The Glycaemic Index of a food represents the time it takes for sugar to appear in the bloodstream after that food has been eaten. Obviously something like plain sugar requires little-to-no digesting and spikes the blood sugar really quickly. In comparison, a dense sourdough rye bread made from stoneground flour, would take rather longer to enter the blood stream. Interestingly and perhaps shockingly, Corn Flakes and very refined white bread have a higher GI than table sugar…… and these are not the worst breakfast items that many people choose! 

So, to avoid the very sugary foods, GI is actually a very useful construct to have. But, how the food manufacturers use this term can actually be quite misleading. For example, Low GI Bread, now supplied by most supermarkets, is the bread of choice for many people. Some are better than others, but all of them are made out of wheat, which is an increasing food sensitivity and all of them have preservatives to make them last longer. Plus some of them aren't particularly low GI. Contrast this with the fresh wholegrain and rye breads that you buy at the counter - if you pick them up and they are the weight of a brick, you can be guaranteed that they are very low GI, but they won't market themselves as such.

Some Low GI products are not actually low GI at all - as you see from the table, the food should have a value below 50 to be able to make this claim. But, I've seen products loaded with sugar and refined grains advertised as low GI - probably just lower GI than some of their competitors - so be careful with label claims - the most important thing is to read the list of ingredients and you'll get a better idea of how good the product is.

Is GL More Appropriate?

If you manage to escape these marketing loop-holes and actually do mostly eat low GI products, you should also be aware of the term Glycaemic Load (GL). You see, the term GI only really applies to carbohydrate products - fat and protein are digested very slowly and have minimal glycaemic impact. So, if you are dutifully buying lots of low GI products, you are unwittingly loading up on carbs. Some people are okay with that, but as we've seen before in these pages, genetically some people do much better on a low-carb diet. So, even on a low GI diet, they can end up over-weight with blood sugar problems. Glycaemic Load, on the other hand, considered both the GI of the food and the quantity. So, you might well be eating low GI foods, but too many of them and you end up with a high dietary GL. So, if you're into your GI diets, you also need to learn about GL. 

Is Low GI Healthy?

"No" is a short answer - that is if you're naively following a low GI diet by looking at the claims on the fronts of food labels. If you're actually consuming what I term "real" foods, like many of the foods that achieve a score of 50 or less on the table, then you're eating much better than average. The further down the GI list you go, the less processed is the food and the more protein and fats you're starting to consume. If you think healthy, think whole food, un-processed, label-free food that came out of the ground, off a tree, from water or was free-roaming on pasture-rich land. 

Protein-Carb Balance

If you've learned nothing yet, please take note of this one - your one take home message. The moment you add fat or protein to a carbohydrate-rich food, the GI goes down. For example, white bread has an extremely high GI - if you add strawberry jam, the GI rises further, whereas if you add sugar-free peanut butter, it drops substantially. As I noted earlier, GI can be a useful concept if used well, so please understand the importance of balancing carbs and fats/proteins in your diet. To reduce the GI of your oats in the morning, add a sprinkle of nuts and seeds and even slip in some whey protein powder. To reduce the GI of your lunch, do away with your sandwich, increase the amount of chicken to the amount of a chicken breast and add a plate-full of salad or veggies. A slice of quality bread can be put on the side, whereas with a sandwich, bread is the main emphasis. Many nutritionists recommend a quarter plate of protein, a quarter plate of starch and half a plate of vegetable matter. See how close you can get.

As you can see, everything on this list is carbohydrate-rich, so the GI concept is a useful one to choose better quality carbs. Ideally, we don't have much in our diet that comes from this High GI list, but it helps you to make the best choices. For example, if you're into your refined, sliced bread, you can easily see why it would be better to eat brown instead of white bread: the white bread is pretty much as sugary as table sugar. Although, it would be even better to drop down to the Low GI list and consume a form of wholewheat bread. There are a few natural, unprocessed items on this list such as carrots, beetroot and potatoes. The more cooked a vegetable is, the higher the GI becomes - a reason to eat your carrots raw or lightly steamed. The sugary potatoes can be balanced by some high-protein chicken or fish or even some sugar-free baked beans. 

More of the foods on this list are natural and unprocessed, so for this reason alone, consuming from this chart gives you more healthy choices. The more fibre and protein or fat that you find in a food, the lower the GI becomes. Fibrous green vegetables, beans and lentils are good Low GI choices. This chart also helps you to make better cereal choices - wholegrain varieties are essential to make it into the Low GI list. Be careful though - if all of your attention goes into the GI of a product, there is a tendency to have a high carb diet, even though they're high in fibre. Some people genetically fair much better on a low-carb, higher fat and protein diet.