Low Glycaemic Index Food – Does the Diet Work?

The beauty and the drama of our modern times lies within one paradox – people in general tend to be more educated than ever, yet millions of people are still interested and want to believe in one magic pill that solves all their problems. This is the primary cause of why we have so many fad diets floating around, yet none of them are good enough. Mainly because none of them are balanced enough. Today we will look into the concept of low GI – the Glycaemic Index. There is a whole diet built around it, but let’s just look at what GI actually means first.


The Basics

In case you have never heard of the term The Glycaemic Index (GI), you have most likely heard of the concept preceding it – simple and complex carbs. As you might know, complex carbs were the good ones that were supposed to keep you full longer and simple carbs were just another term for ’empty calories’ food, food that makes you gain weight in no time. So what is GI?


The GI is a scientific ranking of foods based on their immediate effect on blood sugar levels. Many everyday carb based foods have been tested and given a ranking between 1 and 1000, depending on the speed at which they release their sugars into the bloodstream. Carb foods that break down quickly during digestion have the highest GI (GIs of 70 and above). Their blood sugar response is fast and high. Carbs that break down slowly, releasing glucose gradually into the bloodstream, have low glycaemic (GI of less than 55) indices.


It was believed up until recently that simple carbs consisted of sweet, sugary foods, such as cakes, biscuits, sweets, chocolate, jam and honey. Complex carbs, on the other hand, consisted of more starchy foods, such as bread, potatoes rice, pasta and cereals. It was commonly thought (and that belief is still very common) that the simple carbs caused our blood sugar levels to rise far more rapidly and gave us a quicker energy burst than the starchy, complex ones. Which means that simple carbs gave us only a temporary energy boost, which was followed by a rapid decline in sugar level. This made us more hungry, craving more food and created a vicious fat making cycle.


The revelation of the latest science

It’s all old news. Thanks to the creation of the Glycaemic Index we now know that simple carbs are not as simple as we used to think. Why? Well, because food such as baked potatoes and some types of bread tend to have a far high GI and cause a far greater surge in blood sugar levels than many sweeter, more sugary foods. Our clever mother nature will never cease to surprise us.

How does it work? The GI is a numerical index that ranks carbohydrates based on their rate of glycemic response (i.e. their conversion to glucose within the human body). GI uses a scale of 0 to 100, with higher values given to foods that cause the most rapid rise in blood sugar. Pure glucose serves as a reference point, and is given a GI of 100.

So the conclusion is as follows: the division between complex and simple carbs is not so clear anymore. It gets really confusing if you look into it deeper, because even though many sweet and sugary foods do have high GI’s, some starchy foods like potatoes or white bread score even higher than honey or table sugar!


Why blood sugar level is important?

Your body performs best when your blood sugar is kept relatively constant. If your blood sugar drops too low, you become lethargic and/or experience increased hunger. However, if it goes too high, your brain signals your pancreas to secrete more insulin. Insulin brings your blood sugar back down, but primarily by converting the excess sugar to stored fat. I keep talking about sugar and insulin and I cannot emphasise enough the importance of these two in relation to unwanted body weight gain. Too much sugar = too much insulin = too much fat is stored and that’s where you start losing control of your waistline.

Insulin and sugar is a very tricky couple. The problem is not that insulin is a fat storing hormone, but just to make things more difficult, too much insulin with drive your blood sugar levels back down too low. Too low blood sugar means just one thing – you will experience hunger. You will start again and if you choose food with a high GI, the cycle will just repeat.

When you eat foods that cause a large and rapid glycemic response, you may feel an initial elevation in energy and mood as your blood sugar rises, but this is followed by a cycle of increased fat storage, lethargy, and more hunger! It is a vicious circle.

The theory behind the GI is very simple – it is to minimise insulin-related problems by identifying and avoiding foods that have the greatest effect on your blood sugar. Does it mean that you should never turn to food with high GI and only follow GI system when you choose food? Not so fast.


Should all high GI foods be avoided?

For non-diabetics, there are times when a rapid increase in blood sugar (and the corresponding increase in insulin) may be desirable. For example, after strenuous physical activity, insulin also helps move glucose into muscle cells, where it aids tissue repair. Because of this, some coaches and physical trainers recommend high-GI foods (such as sports drinks) immediately after exercise to speed recovery. It’s another story as to how good these sports drinks are, but technically speaking glucose is our body’s preferred method of fuel and after exercise you should really munch on carbs.

However, it’s important to remember one good old principle – it’s not just what type of food you eat, equally important is the amount of the food that you consume. The concept of GI combined with total intake is referred to something called – Glycemic Load (GL)

How glycemic load improves glycaemic index

Although most candy has a relatively high GI, eating a single piece of candy will result in a relatively small glycemic response and won’t make any difference. There is no need to stress over one tiny piece of chocolate or candy you have demolished in the evening after your tea. It doesn’t count. A box of chocolate, however, counts very much indeed.

Why? Well, simply because your body’s glycemic response is dependent on both the type  and the amount of carbohydrate consumed. This concept, known as Glycemic Load, was first popularized in 1997 by Dr. Walter Willett and associates at the Harvard School of Public Health. Glycemic Load is calculated this way:


GL = GI/100 x Net Carbs
(Net Carbs are equal to the Total Carbohydrates minus Dietary Fiber)
If you really want you can control your glycemic response by consuming low-GI foods and/or by restricting your intake of carbohydrates. You can write a cute little formula to make your life much more difficult.


Disadvantages of the GI only diet

Although methods for determining Glycemic Index have been in existence for more than 20 years, GI values have so far only been determined for about 5% of the foods. Seemingly similar foods can have very different GI values, so it’s not always possible to estimate GI from either food type or composition. This means that each food has to be physically tested. GI testing requires human subjects, which is expensive and time-consuming. Food manufacturers continue to introduce thousands of new foods each year and nobody tests that food for GI, unless it’s a very new and a very posh fad diet or product. Like Agave Nectar, which is just another product of clever marketing and is commonly used by people who are obsessed with some miracle diets, but in essence it’s just another processed pile of rubbish which you should avoid at all costs. Even wikipedia knows that agave nectar’s benefits are non-existent.

There are a couple of GI index tables floating around in the internet and the measurements are not so precise. Reported values are generally averages of several tests. There’s nothing wrong with that methodology but individual measurements can vary a significant amount. For example, baked Russet potatoes have been tested with a GI as low as 56 and as high as 111! The GI for the same vegetable has even been shown to increase as the vegetable ripens. Moreover, food preparation change the GI as well. Generally, any significant food processing, such as grinding or cooking, will elevate GI values for certain foods because it makes those foods quicker and easier to digest. This type of change is even seen with subtle alterations of the preparation, such as boiling pasta for 15 minutes instead of 10.

This amount of variation makes any claims that the GI diet works simply ridiculous, because it’s impossible to follow it accurately and every person reacts differently to different food and food mixes (we never eat food in isolation as we tend to eat a combination of protein, fibre, fat and carbs in any given meal and that mix also effects GI). So if you are wondering if you can just follow the GI diet and it will make you slim and happy in no time, abandon your hopes. But if GI is something you want to consider when you plan your meals and diet in general, then that is one very wise idea.

Finally, it is fundamentally important to remember that the Glycemic Index is only a rating of a food’s carbohydrate content. If you use GI and GL values as the sole factor for determining your diet, you can easily end up over consuming. That is the biggest problem I have with the whole GI diet concept.


Example: how the GI can encourage overeating

Apples have a GI of 38, and a medium-size apple, weighing 138 grams, contains 16 grams of net carbohydrates and provides a Glycemic Load of 6. This is a low GL, and most would consider the apple to be a very appropriate snack. Makes sense? But let’s have a look at peanuts. A 112g serving has a much lower GI – 14, and provides an even lower GL of 2. Based on Glycemic Load alone, you would have to believe that the peanuts were a better dietary choice than the apple. But if you take a look at the calories contained in these two foods, you’ll see that the apple contains approximately 72 calories, while the peanuts contain more than 500! Those 400+ extra calories in one little snack are not going to help you lose weight.((Further info can be found here))

What about satiety?

As you have probably guessed by now, everything about food is a little bit more complicated than we originally though. The obvious way to limit carbs consumption is simply to eat less. This would have been an incredibly effective method for controlling blood sugar and losing body fat. Sadly, our bodies have very little respect for our cute aspirations, therefore there is one big problem associated with this method – increased hunger like that of a racing horse! Is there any way we can eat less, yet still not be hungry? Can we make that happen?

A few years ago, a group of researchers from the University of Sydney performed an interesting study in which they compared the satiating effects of different foods. In this study, the researchers fed human test subjects fixed-calorie portions of thirty-eight different foods, and then recorded the subjects’ perceived hunger following each feeding.

The results of this study clearly indicated that certain foods are much better than others for satisfying hunger. The researchers used white bread as their reference point and assigned it a “Satiety Index” of 100. Foods that did a better job of satisfying hunger were given proportionately higher values, and foods that were less satisfying were assigned lower values. Among the most satisfying foods they tested were plain boiled potatoes, raw fruits, fish, and lean meats. Subjects that consumed the prescribed portion of these foods were less likely to feel hungry immediately afterward. Foods that did the poorest job of satisfying hunger included croissants, donuts, candy bars, and peanuts. ((The result of their study, “The Satiety Index of Common Foods”, was published in the European Journal of Clinical Nutrition, September 1995.))

Unsurprisingly,  the conclusion is the same again – products with lots of sugar will never make you fill full or feel good. If you want to have a good body, accompanied by good skin and well working brain, there is no other better way to get it all by ditching all the processed food and start thinking twice about what we eat and how much we eat.


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