The Glycemic Index And The Glycemic Load

Diets which are rich in high Glycemic food which cause blood sugar levels to spike because they release all the energy immediately into the blood stream, have been linked to an increased risk of diabetes and heart disease. Low Glycemic foods act to help to control diabetes because they keep the blood sugar levels stable, because as they are being digested the glucose levels are released steadily.

One of the factors that influence how the carbs affect our systems is the fibre content. Grains such as wheat have a fibre rich outer bran layer called the outer germ, and an inner germ, which is packed with minerals and vitamins. The fibre content as the outer husk protects the inner starch levels of the food from being digested very quickly. In practice, the less a food is processed the longer it will take the enzymes to digest it and the fibre is released almost undigested. High fibre food takes a longer steadier time to release the glucose into the blood. The riper a fruit or vegetable is the higher the sugar content, and therefore the higher the Glycemic index. That means that green unripe bananas have a lower Glycemic level than the black skinned and very ripe bananas.

However, that is not a full explanation. A baked potato has a high Glycemic index and yet it has not been processed it is merely a potato cooked. The answer here is that the body does not treat all starches the same way; some are harder to break down into sugar molecules than others are. The starch in potatoes is broken down into sugar very rapidly by the body, which accounts for the fact that it is an unprocessed food but has a high Glycemic index. Though in general the finer, the grind a substance is the higher the index, which illustrates why couscous has a high Glycemic level. Unfortunately that is still not the full picture if a substance is high in fat or acid or both the conversion rate in to glucose is slow.

So this is where the conclusion muddies the waters simple sugars such as white sugar are bad for you, as a bald statement that is correct, but simple sugars as in fructose is present in fruit which is good for you. The difference in the sugars and how the body treats the carbohydrates accounts for the fact that most diabetics are recommended to eat fruit despite its sugar content. The acid content of fruit prevents it from being absorbed into the blood stream quickly.

However the Glycemic index alone is not an indication of the relative carbohydrate in food. Watermelon is composed of mostly water as it rather prosaic name would suggest, but it has a high Glycemic index, yet a low carbohydrate level. Modern research is developing new classifications that go beyond the simple carbohydrate levels, but another factor must be taken into account and that is how fast those cabs are released into the blood stream. This new indicator is called the Glycemic load. The formula for determining a Glycemic load is the product of its Glycemic index and the amount of carbohydrates it contains.

The chemistry of this is complex but the message is simple when the body cannot manage its sugar levels the pancreas has to make more insulin which signals the cells to store the energy contained in glucose.

As the cells absorb the levels of glucose the level in the blood stream drops down to the level it was before digesting the glucose and the insulin production is halted as well. Insulin resistance occurs when both the glucose and insulin levels remain high for too long after eating. Over a period of years, this puts pressure on the insulin production causing it to slow down and then stop completely. However, this is not simply a problem that leads to diabetes it has links to some cancers heart disease and high blood pressure amongst other health problems.

Eating whole grains is not just a matter of a diet it is a lifestyle to ensure a long and healthy life. That means that there are some good carbohydrates, and these protect you against insulin insensitivity.

If you want to go the lower carb route when you are dieting include some fruits, vegetables, and whole grain carbohydrates every day. They contain nutrients that the body needs and they cannot be bought in a bottle as a health supplement. They include whole wheat bread, brown rice, whole grain high fibre pasta, and other grains such as quinoa, whole oats, and bulgur. Cut down on the potato and use it as a special treat not an everyday fare.

As a general rule use the table below and eat foods with a high Glycemic load very sparingly or as a treat and eat the foods with low Glycemic index on a daily basis. This is not just if you are dieting, it affects everyday health and fitness and it is a concept that goes way beyond the diet. It is a recipe for a healthy old age, a healthy diet maximises your chances of being fit and healthy for longer.

Carbohydrates and the Glycemic Load International table of glycemic index and glycemic load values: 2002. Am J Clin Nutr 2002; 76:5-56.
Foods with low Glycemic loads	Foods with Medium Glycemic loads	Foods with High Glycemic loads
High fibre fruits such as blackberries, apples pears and raisins. High fibre vegetables, which include peas, all types of beans, lentils, and chickpeas. Bran cereals.	Brown rice, including brown basmati. oatmeal bulgur, pearl barley, oranges, and wholemeal breads and pasta.	Potato both fired and baked or pureed. Refined breakfast cereals and especially those that have been coated in sugar. Couscous White rice White flour Cakes sugar Biscuits candies and chocolates.