A new concept, called the glycaemic load (GL), which was developed by scientists from Harvard University, USA,  “fine tunes” the Glycaemic Index (GI) concept. It addresses concerns about rating carbohydrate foods as either “good” or “bad” on the basis of their GI. There is no such thing as a good or bad carbohydrate food. All carbohydrate foods can fit into a healthy diet”)  – it all depends on when you eat it, how much you eat and with what you combine it. For example, although low GI food is usually the preferred choice, a high GI sports drink is perfect during and after running a marathon, as a low GI drink during or after intense exercise could, in fact, can result in hypoglycemia and insufficient replenishment of carbohydrate in the muscle and liver.

The glycaemic load (GL) of a specific food portion is an expression of how much impact (“oomph”), or power the food will have in affecting blood glucose levels. It is calculated by taking the percentage of the food’s carbohydrate content per portion and multiplying it by its Glycaemic Index value

GL= CHO content per portion x GI

100

 It is thus a measure that incorporates both the quantity and quality of the dietary carbohydrates consumed. Some fruits and vegetables, for example, have higher GI values and might be perceived as “bad”. Considering the quantity of carbohydrate per portion, however, the GL is low. This means that their effect on blood glucose levels would be minimal. Let us consider a few examples:

* The GI of watermelon is high (GI = 72), but its glycaemic load is relatively low (GL = 7), because the quantity of carbohydrate in a serving of watermelon (150 g or a 5 mm thick slice) is minimal, as it contains a lot of water. This does not hold true for watermelon juice, however, as the quantity of carbohydrate in a cup of watermelon juice (250 ml) is much higher and fruit juice is therefore a more concentrated source of carbohydrate.

* The GI of apples is 38 and the GL of one medium apple is 5. This means that eating one apple will have hardly any effect on blood glucose levels. If you eat an entire 500 g packet of dried apples, however, its GL would be 50, which means that it will have a huge effect on your blood glucose levels, despite its being low GI. This brings us back to the old principle that there is no license (I changed the second c to an s; spelling mistake) to overindulge in “good” or “bad” foods. But should you indulge in watermelon, it will have an even greater effect on blood glucose levels, due to its high GI value!

* The GI of SA brown bread is high (GI = 81) and the GL of two slices (2 x 40 g slices of bread containing 20 g carbohydrate each) is also high (GL = 32), because the quantity of carbohydrate in a hand-cut slice of bread is substantial. This means that a sandwich made with two slices of brown bread will have a marked effect on blood glucose levels as the bread will have an “oomph” of 32. On the other hand, if you use a thin slice of bread (30 g bread containing 15 g carbohydrate) as part of a mixed meal containing low GI baked beans, ham and salad vegetables, the GL of the meal will be lower and more acceptable (GL = 22). Note that the two slices of bread on their own have a higher GL than an entire meal, in which only one thin slice of bread is used in combination with other low GI foods.

* The glycaemic load (GL) of one slice of seed loaf is only 8. In contrast to this, a single hand-cut slice of brown or white bread has a GL of 16. This means that ordinary brown or white bread will spike blood glucose levels (higher GL), and the seed loaf will not (lower GL), but this still doesn’t mean that you can over-indulge in seed loaf. Fortunately, seed loaf is more filling and it is not as easy to over-indulge in this bread, as it is to over-indulge in brown or white bread.

* In addition, the GL of a roll (equivalent to two slices of bread) is more than 20, and that of a bagel (equivalent to three slices of bread) is more than 30. Imagine what this does to blood glucose levels, as the GI is also high!

* From this we can see that it is quite acceptable to include small quantities of high GI foods in a meal, as long as the bulk of the meal contains lower GI carbohydrate foods (vegetables, fruit, low GI starches, legumes and/or dairy).

New evidence associates high GL meals with an increased risk for heart disease and diabetes, especially in overweight and insulin-resistant people. Therefore, it is advisable to restrict the GL of a typical meal to between 20 and 25 as far as possible, but definitely to keep it below 30. The GL of a typical snack should preferably be between 10 and 15, but if your meals are all close to 30, the total of your snacks should be no more than 10. This means that you would have to eat fruit for snacks, in order to keep your total daily GL below 100, as the GL of fruit is usually below 10.

What does it mean when a food has a low glycaemic load?

A carbohydrate food that has a low glycaemic load (GL) will have a small impact on blood glucose levels, as it is either not high in carbohydrate and/or has a low Glycaemic Index (GI) one would have to eat quite a lot of it before it will have any effect on blood glucose levels. In other words, eating any one of the muffins contained in this lower GI, lower fat recipe book or in Eating for Sustained Energy 1, should not raise blood glucose levels significantly, as they have a lower GL. Having a low GL and a low Glycaemic Index (GI) is doubly beneficial. A food with a low GI and very little “push” or “power” (GL) behind it, will naturally have a very small impact on blood glucose levels, such as low GI vegetables (tomatoes, lettuce, cucumber, onions, asparagus, mushrooms, etc). It follows then that these foods are also not very effective at lowering the GI of high GI foods such as white or brown bread.

Remember: The GI indicates the extent to which a food will raise blood glucose levels, whereas the GL is the “power” or “push” behind the GI.

High GI and high GL means trouble – blood glucose levels will shoot up. This means the food in question will have a lot of “power” behind the already high GI, and even a small portion will have a marked effect. Examples of this are cooked mealie meal and potatoes and the regular SA bread mentioned above. These foods are high in carbohydrates and therefore a small portion already contains a lot of carbohydrate. In addition they have high GI values, which aggravates the effect on blood glucose levels.

Low GI combined with a high GL will also impact on blood glucose levels. Remember that the GL is based on the quantity of carbohydrate in a food, and represents the GI in portion size. So the more carbohydrate there is in a food, the higher its GL i.e. the more “power” or “push” behind the GI.

So even low GI foods, if eaten in large quantities, can affect blood glucose levels quite significantly, especially if they are concentrated sources of carbohydrates e.g. most cakes, dried fruit and dried fruit bars, fruit juices, crisps, chocolates, etc. Crisps and chocolates are also high in fat and/or saturated fat, making them undesirable.

And lastly, a high GI food with a low GL will not necessarily affect blood glucose levels significantly. A good example here is the high GI vegetables (carrots, pumpkin, etc). They contain only a little carbohydrate and therefore, in normal portion sizes, will not impact on blood glucose levels even though they have a high GI, as there is not enough “power” behind the high GI. The proviso is, though, that they are not eaten with other high GI or GL foods.

Please note that the glycaemic load (GL) of the starch component of most of our low GI breakfasts (such as those in all our lower GI, lower fat recipe books) is about 15, the GL of the starch component of most low GI light meals in our recipe books is between 15 and 20 and the GL of most low GI main meals is about 20. This means that three meals per day should add up to a GL of between 55 and 70, as most people will add salad and/or fruit to breakfasts and light meals, which also contribute to the GL. This leaves 30 – 45 GL points for snacks and drinks, as most of these have a GL of 10 – 15, except for fruit, which has a GL of below 10.

The aim is to keep the total GL per day under 100.