top of page

The Glycemic Index

Updated: Apr 9, 2023

Did you know that bananas provide energy at different speeds depending on how ripe they are?

Yep, it's true!

This is all thanks to the Glycemic Index!

The Glycemic Index

●Rates how quickly carbohydrates raise the blood sugar level

●Carbohydrates are broken down into glucose

●Carbohydrates include breads, pasta, rice and fruit

It is a rating system from 0 - 100

0 - 55 = low GI

55 - 70 = Medium GI

70 - 100 = High GI

When we eat carbohydrates, they are broken down into glucose in the blood stream. This raises our blood glucose levels.

High blood glucose levels are not good for us for there are a few important compounds that help regulate this:

  1. Glucagon: if blood glucose levels are too low, glucagon comes out from the liver in the form of glucose. This raise blood glucose levels

  2. Insulin: if blood glucose levels are too high, insulin is release and stores the excess glucose back in the liver as glycogen

This is how insulin helps regulate blood glucose levels throughout the day:

Glycaemic Load (GL)

●A ratio of GI index compared to amount of carbohydrates

●GI Load = GI index X carbs in grams / 100

●Example: apple = 40 GI, 15 grams GL = 40 x 15 / 100 = 6

Glycemic Index (GI ) vs Glycemic Load (GL)

It is useful to consider both the Glycemic Index and Glycemic Load of different foods. Some foods may have vastly different GI's compared to GL's. In general, Glycemic Load can be a more useful and accurate way to evaluating how the body will deal with glucose.

Different Forms of Food and GI Index

● Some foods can be high OR low GI depending on it’s form.

Eg: Orange (43) vs orange juice (70)

● Influenced by fibre and/or processing

● Eat natural foods!

How to use the GI Index to improve health

●Increasing blood glucose levels quickly and continually throughout the day is very unhealthy! Can lead to diabetes, obesity and heart disease

●Eating low or medium GI index foods leads to more continual blood glucose levels, which means more steady energy levels. Less energy swings!

●Eating fibre can help to slow down the rise of blood sugar levels

The secret to athletic performance!

●Understanding the GI index system is key to improving performance!

●Eating low GI foods before sport will provide a long lasting, sustainable energy

●Eating low GI foods provide a quick energy spike, perfect for just before a game or at half time!

The secret to body composition!

●Understanding the GI index system is key to managing weight!

●High GI foods raise blood sugar levels quickly, if your body doesn’t use this energy then it stores it as fat

●Conversely, using GI foods can help to increase muscle mass when combined with exercise

Summary: Glycemic Index

●GI index goes from 0 -100

●Eat more low GI food for better health and athletic performance (< 55)

○Wholemeal pasta, bread and rice

○High GI foods = lollies, white bread

●Glycaemic Loading (GL) = GI x amount (grams) / 100

Want to learn more? Check out all PE Buddy's videos

Check out our website for more

Get teaching resources for this topic

Thanks legends!

Mr D, your online PE Buddy

16 views0 comments

Recent Posts

See All


Rated 0 out of 5 stars.
No ratings yet

Add a rating
bottom of page