What is Glycemic Index and Glycemic Load?

Sugar has a closed relationship with carbohydrate. Discussing about carbohydrate can't be separated from discussing about glycemic index and glycemic load. This article will further discuss about what is glycemic index and glycemic load?

Previously, experts had divided carbohydrate into two categories; simple carbohydrate and complex carbohydrate. Complex carbohydrate was considered to be healthier.

Nowadays, many researches reported that classifying carbohydrate into that two categories is not enough. Complex carbohydrate is not always better than simple carbohydrate.

There's other factor that should be put into consideration when choosing carbohydrate, which is; how is the effect of the raise of blood sugar level.

In this case, Glycemic index shows how our body respond (a.k.a; blood glucose rise) after consuming certain amount of certain carbohydrate.

Glycemic index has been widely used to help diabetic patients managing their carbohydrate consumption. Lately, glycemic index is also used by those who want to arrange their body weight.

What is glycemic index?

Blood sugar level will rise any time our body consume carbohydrate. However, the raise of this sugar level will not be the same between one carbohydrate and the others.

For example; a glass of sweet orange juice will raise blood glucose more significantly than a cup of oatmeal.

Oatmeal need more time to raise blood sugar because of its carbohydrate type and its fiber content.

So, glycemic index is a numerical value that used to indicate how fast a certain food can raise the blood sugar levels. The higher the glycemic index of a food, then the faster that food is metabolized.

What factors that affect glycemic index?

- Processed food

Processed cereal has higher glycemic index than its original kernel.

- Ripeness of fruit

An unripe banana has glycemic index 43, while the ripe one has glycemic index 74.

- Protein content

Soy bean has low glycemic index.

- Fat content

Peanut has a very low glycemic index.

- Fiber content

Orange juice has higher glycemic index than orange fruit.

- Particle's size

A whole kernel seeds usually have lower glycemic index. However, if they're grinded to be flour, it will raise the glycemic index.

So, which one is better, food with low glycemic index or high glycemic index?

Mainly, but not all, foods with low glycemic index is healthier, more nutrient rich, low processed and fiber-rich. For example; fresh fruit and vegetables, seeds and nuts.

When is glycemic index told to be low?

Low glycemic index: <55

Middle glycemic index: 56-69

High glycemic index: >70

How come low glycemic index food can help reduce weight?

Foods with low glycemic index require longer time to be converted into glucose. This phenomenon can help someone to feel full in longer time.

Meanwhile, foods with low glycemic index will be metabolized faster, so it will also make someone feel hungry faster.

In a research, dr. Ludwig from Children's Hospital Boston explained that low glycemic index food can reduce the feeling of hunger in young teenage boy who obese.

However, glycemic index has weakness. It used one meal time amount as basic standard (50 grams). For example; carrot has high glycemic index. However, to reach 50 grams of carrots, we have to consume at least 4 cups of chopped carrot. That's why; the concept of Glycemic Load was developed. Glycemic Load use also serving size as basic standard.

Glycemic load is the younger brother of glycemic index. Glycemic index itself was born in 1981 from the uterus of 2 researches from Toronto University; Dr. Thomas Wolever and Dr. David Jenkins. However, the weakness of glycemic index is that it does not put carbohydrate amount into consideration.

Glycemic index only measures the ability of 25-50 gram of carbohydrate to raise the blood sugar level. On the other hand, every food has different carbohydrate amount (in same serving size). Because of that reason, research team from Harvard created glycemic load. Glycemic load is the numerical value shows how certain food raise the blood sugar levels, but also put carbohydrate amount into consideration.

By the way, why does carbohydrate amount have to be put into consideration?

In some cases, glycemic index can be a trap. Let's take a look on a watermelon. Watermelon has a high glycemic index. But, in a normal serving size, watermelon does not contain much carbohydrate, because water is its main content. The low content of carbohydrate makes its glycemic load is also low, which make the low effect of glycemic index. If glycemic index is used as the only standard, watermelon can be totally avoided by those who has diabetes or obese.

That's why; glycemic load can be a better reference which is much more flexible than glycemic index. When glycemic index only refers to the kind of carbohydrate, glycemic load also refers to the serving size, one meal size and even daily meal size.

Food is said to have low glycemic load if the value is less than 10; middle glycemic load if the value is 11-19; and high glycemic load if the value is more than 20.

The fact is; almost all foods with low glycemic load also have low glycemic index. But foods with middle to high glycemic load may have very low to very high glycemic index.

The next question is probably how to count glycemic load?

Now let's go back to watermelon case. The glycemic index of watermelon is 72 (pretty high, right?). In every 100 grams of watermelon contains 5 gram carbohydrate. So, the glycemic load is 5 x 72 / 100 = 3.6 (low glycemic load).

In the same way, if certain food with glycemic index 100 but only contains 10 gram carbohydrate, it will have glycemic load 10 (10 x 100/100 = 10). On the contrary, food with glycemic index 10 but contain 100 gram carbohydrate will also have glycemic load 10 (100 x 10 / 100 =10).

I'll repeat the formula to count glycemic load as follow;

Glycemic Load = Carbohydrate content in 100 gram x glycemic Index / 100

Now, let's see other example; tortilla. It has glycemic index 52 (low glycemic index), but it contains 48 grams carbohydrate every 100 gram of serving size. So, the glycemic load will be 58 x 52 / 100 = 24.96 (high glycemic load). It strengthen the fact that using glycemic index as the only reference to choose your diet is not enough.

To get a complete list of almost 2500 kind of foods with their glycemic index and glycemic load, you can type this address on your browser; http://www.mendosa.com/gilists.htm