Everything you need to know about Glycemic Index

Who here hasn’t heard of this condition called diabetes?

Diabetes is characterised by high blood sugar levels in blood causing all sorts of unwanted consequences.

What happens when we take in sugar – or carbohydrates

it causes a sugar spike in our system.

And when your body detects the sugar spike, it will order the pancreas to release a chemical called insulin.

And insulin converts the sugar to other substances to be stored in your body for use later.

The whole process is efficient, when there is extra sugar, insulin changes the sugar to storable energy form. And when we are in situations where extra energy is needed, our bodies then convert these stored energy back to sugar to fuel our needs.

Now imagine this for a second,

Everytime when you take in sugar, you force your pancreas to “wake up and work”. The “sharper” the spike, the harder your pancreas will have to work to restore the sugar balance.

think about it this way: Which one is easier? suddenly forcing yourself to lift a 150kg barbell without any warm-up for just 10 reps or gradually increasing the weights to maybe a maximum of 70kg over half an hour

Over time, if you keep on taking sugar that will cause sharp spikes in blood sugar levels, you can tire out your pancreas. And that’s what happen to people with type-2 diabetes.

Their pancreas becomes insensitive and their insulin produced becomes inefficient in sugar conversion.

Also, our bodies like stability. When they detect a sudden sugar spike, we release insulin to convert those sugar. The sharper the spike, the more insulin we will produce.

And sometimes in the process, we will over-produce insulin – and cause an eventual dip in sugar level (hypoglycemia). And low sugar makes us crave for more sugar and the vicious cycle continues.

The key, is to avoid foods that cause sharp sugar spike. And instead go for foods that slowly increase the sugar levels. It gives us more time for our bodies to assess the situation and respond appropriately without over- or under- reacting.

Glycemic Index: A ranking system for carbohydrates

In year 1981, two brilliant scientists at University of Toronto , Dr Thomas Wolever and Dr David Jenkins came up with the Glycemic Index ranking system.

Basically, Glycemic Index is a system that measures how quickly a food containing 25g to 50g of carbohydrate raises blood-glucose levels.

Pure glucose has a glycemic index score of 100 and acts as the benchmark for other carbohydrates. The higher the glycemic index score of a food, the faster it causes a sugar spike in your body after consumption.

Related reading: 7 Supplements you might want to get if you are diabetic

List of Glycemic Index of food

As mentioned, the higher the Glycemic Index score of a food, the faster it can cause a sugar spike in your body after being eaten.

And to determine if a food has high or low glycemic index, food scientists have come out with three different categories:

  • Low GI foods: Foods with GI score of 1 to 55
  • Medium GI foods: Foods with GI score of 56-69
  • High GI foods: Foods with GI score of 70 and above

Glycemic Index of foods (Malaysia version)

In this section, we have compiled a list of common Malaysian fruits and foods and their GI score respectively.

 

Low GI foods (Malaysia version)

Apples (120g) – 40

Apple juice (250g) – 39

Bananas (120g) – 47

Grapes (120g) – 43

Mangoes (120g) – 51

Oranges (120g) – 48

Pineapple (120g) – 51

Carrot juice (250g) – 43

Carrots (80g) – 35

Sweet Corn (80g) – 55

Yam – 37

Potato white, boiled (150g) – 54

Barley (150g) – 22

Basmati Rice (150g) – 52

Bran cereal (30g) – 43

Brown rice, steamed (50g) – 50

Instant Noodles (180g) – 52

Instant Oatmeal (25g) – 50

White rice, boiled (150g) -47

Skim Milk (250g) – 32

Soy Milk (250g) – 43

Cashews (50g) – 25

Corn chips (50g) – 42

Ice cream, full-fat, French vanilla (50g) – 38

Ice cream, low-fat, vanilla, “light” (50g) – 46

Oatmeal cookies (25g) – 54 Sushi (100g) – 55

Medium GI foods (Malaysia version)

Cherries – 63

Kiwifruit (120g) – 58

Pumpkin (80g) – 66

Sweet potato, boiled, (150g) – 61

All-Bran bread (30 g) – 60

Hamburger bun (30g) – 61

Linguine, fresh, boiled (180g) – 61

Pita bread, white (30g) – 57

Special K cereal (30g) – 69

Croissant (57g) – 67

Honey, pure (25g) – 58

Nutri-Grain bar (30g) – 66

Sugar, table (25g) – 65

High GI foods (Malaysia version)

Watermelon (120g) – 80

Potato, mashed (150g) – 88

Corn Flakes (30g) – 79

Gluten-free bread, multigrain (30g) – 79

Rice, instant, cooked 6 min. (150g) – 87

Tapioca, boiled with milk (250g) – 81

Muesli (30g) – 86

Waffles (35g) – 76

White bread (30g) – 70

French fries (150g) – 75

Doughnuts, cake (47g) – 76

Glucose (10g) – 96

Pizza, cheese (100g) – 80

Japanese style sushi rice, SunRice – 89

Jasmine fragrant rice, SunRice – 73

How to use glycemic index to help control your blood sugar

Great!! So now I know that my favourite breakfast – Muesli – is a high GI food (thanks), but now what?

Does that mean I should never ever eat muesli or white bread or Sushi ever again?

Relax. 

Glycemic index is great for comparing carbs, but it’s by no means a diet restriction tool.

Say for example, we now know that long grain rice has lower GI than short grain rice. If you are a rice eater (like most of us in Malaysia), maybe you can consider swapping to Basmati rice from Jasmine fragrant rice?

Or instead of potato chips, you might want to consider taking sweet potato chips instead?

Now, before we go any further into diet planning using Glycemic Index, let’s first go through a few other factors that affect the glycemic index score of a food.

What affects the glycemic index of food

Why do mashed potatoes have higher GI than boiled potatoes? Why do fruits have generally lower GI eventhough they taste sweet?

A number of factors are found to affect the glycemic index score of a food. These include: The amount of fibres present, the chemical structure of carbohydrates, how carbohydrates are prepared, and the amount of fat, protein and acid content.

Factor affecting Glycemic Index Score: Amount of fibre present in food

Fibre is the indigestible parts of plants, seeds and fruits. When ingested, they don’t get absorbed into our bodies (indigestible) and form the bulk of our stool.

Technically, fibres are considered carbohydrates but as they do not get absorbed, they don’t generally cause a raise in blood sugar levels.

The higher the amount of fibre present in food, the lower the GI score of the food

Fibre, especially the insoluble fibre, coats the other digestible portions of carbohydrate and protect them from being absorbed too quickly. The slower the carbohydrate gets absorbed, the longer it will take for it to cause a sugar spike.

High amount of fibre – this is the reason why fruits generally have low GI eventhough they taste sweet.

What affects glycemic index score: The chemical structure of carbohydrate

We all know that carbohydrates can be loosely categorised into simple carbohydrates (monosaccharides & disaccharides) and complex carbohydrates (polysaccharides).

Loosely speaking, the more complex the chemical structure of a carbohydrate is, the longer it takes for our body to digest it. Hence, complex carbohydrates almost always have lower GI scores.

The exact chemical composition of the carbohydrate will also have a big impact on the glycemic index score. Different simple carbohydrates can have very different impact on the glycemic index score. For example, fructose (fruit sugar)has a GI score of 23 and glucose has GI score of 100 – eventhough they are both simple carbs.

And complex carbs are built on combination of different simple carbs. That means if a food contains more fructose molecules in its chemical composition, it will likely to have lower GI score. Another reason why fruits generally have lower GI score.

How you prepare the food affects the Glycemic Index

If you have cooked maggie mee yourself before, you would know that the longer you cook it, the softer the noodles become. Heat breaks down the chemical structure of food and make it softer and easier to be digested.

And the easier it is to be digested, the faster it can cause a rise in blood sugar. This is why porridge has higher GI than rice.

Another factor that affects the Glycemic Index score of a food is the amount of processing. Generally speaking, the more processed a food is, the easier it is for us to digest it.

Similar to applying heat, food processing involves mechanically or chemically breaking down the food to make it edible or taste better. During the process, the food molecules are broken into smaller pieces – making it easier to be digested.

The amount of fat, protein and acid content in food affects the Glycemic Index Score

Put simply, fats and proteins are different from carbohydrates and require extra steps to be digested. Therefore, if a food contains high portion of fats and/or proteins, it will take longer for our bodies to actually digest the carbohydrates. This explains why potato chips have lower GI score than baked potatoes. (Oh really?!!)

Another interesting finding is that when the acidity of a food is high, it takes longer for food to be digested. In other words, high acidity food will generally have lower GI score too.

Quick diet planning tips using Glycemic Index Score

Glycemic Index alone is usually not a very comprehensive diet planning tool.

But it’s a good starting point to compare food choices.

Instead of white bread (High GI), why not go for all-bran bread (moderate GI)? Or boiled potato over mashed potato?

And now that we know that processed foods have higher GI, why not go for the unprocessed version of the same food?

What to do if you know you are going to have high GI food?

If high GI food is really unavoidable, we have learnt that fats, proteins and acid help to lower the GI. Just look at your meal as a whole. If you need to have this mashed potato, balance it out with a good amount of protein and fats (meat).

Another great easy tip is to add lemon juice into whatever dish you are having. Not only does it make the food taste better, it also increases the Glycemic Index Score of the food.

Conclusion

In this post, we have covered almost everything you need to know about Glycemic Index and how you can actually apply the knowledge in real life.

What do you think? Will you be watching what you eat more carefully in the future?

Next time when you are out at the food court,would you still choose sugar cane drink (high GI) over Barley without sugar(Low GI) ?

Related reading: 7 Supplements you might want to get if you are diabetic