glycemic index

Your Beginner’s Guide to Glycaemic Index

What is Glycaemic Index (GI)?

You may have heard of low GI celebrity diets or seen low GI on food packets, but what does glycaemic index actually mean?

Glycaemic index is a measure of how quickly a carbohydrate food raises your blood glucose levels.

It ranges from high GI carbohydrate (fast at raising blood glucose) to low GI carbohydrate (slow at raising blood glucose) and everything else in between.You may have been recommended to choose low GI foods.

This is why…..

Glycaemic index graph

High GI

High GI carbohydrates break into glucose very quickly which causes a spike in your blood glucose levels. High GI foods also disappear from your body fairly quickly. This can leave you feeling hungry and cause a crash in your blood glucose levels shortly afterwards.

High GI foods and drinks make ideal hypo treatments because they work so quickly.


Low GI

Low GI carbohydrates break down slowly. They cause a more gradual and sustained increase in your blood glucose levels. Which means they hold your blood glucose levels steady for longer and also help to keep you feeling fuller for longer.


So how do I choose low Glycaemic Index foods?

Have a look below for some healthy low GI swaps

swap high GI to low GI
Breads white breads Authentic sourdough, wholegrain bread, multigrain bread, fruit bread, corn tortillas.
Cereals Most refined, commercial, processed cereals Wholegrain high fibre cereals, oats, sugar free muesli.
Starchy vegetables Potatoes: mashed, chips and French fries sweet potato, yam.
Rice Jasmine, arborio, glutinous, basmati, brown or white rice Basmati, low GI white or brown rice e.g. Doongara, prepared sushi made from traditional Japanese rice quinoa
Pasta, noodles and grains Polenta, millet Hokkien/ udon/ rice noodles, pasta cooked ‘al dente’, soba noodles, pearl couscous, quinoa, pearl barley, vermicelli, semolina.
Legumes All lentils, baked beans, barlotti beans, kidney beans, chickpeas, butter beans, canolini beans.
Snacks Sugary drinks, doughnuts, confectionary, processed fruit bars, pretzels, rice cakes and crackers. Fresh fruit such as apples, pears, bananas, grapes, kiwi fruit; wholegrain crackers; dried fruit and nuts; low fat yoghurt, nuts, seeds.

Bear in mind that not all low GI foods are great for you. Chocolate is a low GI food because the fat content slows down the release of the sugar. Keep your healthy eating hat on and only choose healthy low GI foods regularly.


What else affects GI?

The GI of a food can be changeable, have a look below to see what you could do to affect the GI of a food.


peanut butter

Team a high GI with a low GI food, this will balance the overall GI of the meal.

Sometimes you cannot avoid having high GI foods.  To reduce the peak in your blood glucose you could team it up with a small amount of low GI food e.g. white bread and peanut butter.



Al Dente

Cook pasta and noodles so they are still on the firmer side. This makes them harder for your body to digest so the glucose is released more slowly.


Use healthy fats

Fat can lower the GI of food, but you need to make sure they are healthy fats. A mountain of extra butter would not be good for your heart.

Also bear in mind that fats contain lots of energy, this is important to know if you are watching your weight.

Wholegrain Bread


Processed foods tend to be higher GI. This is because they have already been broken down to some extent.

For example: in white bread, the wheat has been milled with the husk and bran removed so it is easy to digest.

Wholegrain bread gives the body more work to do, it takes longer to digest, so the carbohydrate is then released more slowly.


What have we learnt?


So, we know that low GI foods can improve your blood glucose, in fact studies show it can lower your HbA1c by up to 0.5%.

Along side reducing your portions of carbohydrate and other lifestyle changes, GI can be a useful tool to manage your blood glucose levels.



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