Glycaemic index & Glycaemic load: how to keep blood sugar levels under control

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Whether you’re a diabetic wanting to take control of your blood sugar levels, or you’re looking to lose weight and have been advised to look for ‘low GI’ carbs, here’s a few things to look out for.

When you talk about carbs, you might hear phrases thrown around like Glycaemic Index (GI). Generally, it’s best to avoid foods higher on the GI scale like white bread, basmati rice and sugar. These carbs quickly turn to glucose, causing your blood sugar levels to spike then plummet. But rather surprisingly, healthier options such as carrots, pineapple and raisins actually have very high GI scores. What’s happening there?

Before you start chucking out all your delicious fruits and veggies, it might be best to consider something called Glycaemic Load (GL). It's basically another tool for weight and blood sugar level management that might be a bit more helpful than GI. Before we get into explaining these terms, let’s firstly take a look at why you might want to control your blood sugar levels. Then, we’ll talk about how you can do that through your diet.

Blood sugar levels under control

The practice of keeping your blood glucose in the correct ranges is typically referred to as glycaemic control. It’s normally an approach taken by people with Diabetes Mellitus. But, taking this approach to your diet and lifestyle can be beneficial to everyone.

Your blood glucose levels move out of the ‘normal’ range in the following ways:

Too high:

High blood glucose levels can happen if you eat too much, forget to take your diabetes medicine, or don’t exercise enough. Your body reacts by releasing insulin into the blood to help store the excess glucose in the form of fat. You might experience:

  • Excessive thirst or hunger
  • Blurred vision
  • Feeling sick
  • More frequent urination

Too low:

A drop in blood sugar can be caused by missing a meal, taking too much insulin or drinking too much alcohol. You might feel:

  • Low in energy
  • Weak, light-headed or dizzy
  • Very hungry
  • Like you're craving foods

If you can effectively maintain control over your blood sugar levels, you’ll avoid both of these unwanted scenarios. You’ll have much more stable energy levels throughout the day, allowing you to perform better physically and mentally. And you won’t increase your amount of body fat either!

Glycaemic Index and Glycaemic Load

By familiarising yourself with Glycaemic Index and Glycaemic Load, you can much better understand how to control your blood glucose. Let’s define what they mean:

  • Glycaemic Index (GI) refers to the effect that a food containing carbohydrates has on resting blood glucose levels.
  • Glycaemic Load (GL) is an extension of GI, which takes the total carbohydrate content of the food into account. This gives you a much more accurate picture of the overall effect that food has on your resting blood sugar levels.

To calculate GL, simply multiply the GI of the food by the carbohydrate content of the serving size you’re having, then divide by 100. For example: in 100g of a white baguette with a GI of 95, there’s 50g of carbohydrates. So, 95x50=4800. 4800/100=48.

wholegrain pasta carbohydrates glycemic control

Guidelines for glycaemic index and glycaemic load

If you’re trying to control your blood glucose levels, you should generally follow these GI and GL guidelines:

  • For Glycaemic Index, anything less than 55 is low; high is 70 or higher.
  • For Glycaemic Load, anything less than 10 is low. 11-19 is medium. 20+ is high.

If you're attempting to lose or maintain weight or want to keep blood sugar levels balanced, GP Dr Brian Fisher recommends a diet consisting of mainly low-GI and low-GL foods: "try to ensure you don't consume lots of foods with medium to high GI or GL values." He says that "this will help keep blood glucose levels within the normal range and allow your body to function more easily without storing too much extra body fat or getting loads of food cravings."

Low-GI and low-GL foods

When it comes to GI and GL, it's generally best to stick to foods that score low for both. This includes:

  • Fruits and vegetables, e.g. sweet potatoes, peas and apples
  • Pulses e.g. lentils and chickpeas
  • Whole grain products (e.g. brown rice, oats and wholemeal pasta)

High-GI and high-GL foods

It's also best to avoid high glycaemic foods, including:

  • Sugary foods e.g. cakes and biscuits
  • Sugary soft drinks
  • White carbohydrates (e.g. bread, pasta and rice)
  • Fruit juices

Everyone’s different

Not everyone reacts in the same way to the same foods. With DNA Metabolic Testing, your unique genetics can reveal how you metabolise carbohydrates and how they might impact your blood sugar levels.

But I thought that was healthy …

There are a few confusing foods when discussing healthy eating that stir some contradicting opinions depending on who you speak to and what you read. Take these for example:

Pasta (Fusilli) – GI of 37, average serving of 180g, carb content of 56g, GL of 27

Raisins – GI of 54, average serving of 30g, carb content of 21g, GL of 29

Sourdough bread – GI of 53, average serving of 80g (two slices), carb content of 41g, GL of 28

All these foods would be classed as high GL despite the GI being low. Evergreen Life fitness fanatic and Wellbeing Expert, Matt Jolley says "it might be best to avoid these foods if weight loss or weight maintenance is your health goal – even fruits like raisins!"

Special mention:

With a low GI of 48, milk chocolate might fool you into thinking it’s not that bad for your blood sugar. That’s because of its high fat content... The high amount of sugary carbs still places its GL at 29 – and that’s even if you only have 4 squares of it!

different types of carbohydrates potatoes pasta glycemic control

It’s not all bad news …

What about high GI and low GL?

GI takes into consideration large quantities of food that wouldn’t represent a typical serving size. A high-GI food might rank quite low for GL, because there’s not much total carb content in a given serving of that food. Low GL is the better indicator that a food won’t have much impact on blood glucose levels.

For example, 5 cups of watermelon have a high GI of 72. Yet, if you take a realistic serving size of 1 cup of watermelon, its GL is 7. So, although the GI indicates the watermelon would spike your blood sugar, it doesn’t actually contain much carbohydrates as it’s mostly water. We can see from its low GL that watermelon won’t impact your blood glucose too much.

But, if you go juicing fruits or veggies their GL will go up because you’re consuming much more food in one go – this’ll have a much greater impact on blood glucose.

Take control of your health today

If you’re a diabetic and regularly monitor your glucose levels, did you know you can easily keep track of your levels in the Evergreen Life app? You can monitor this over time and work out what’s impacting them.

Take control of your health and wellbeing today.

Written by
Evergreen Life

Article updated:
July 9, 2018
Reviewed by:
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