Let’s start with the meaning behind both terms.
The glycemic index (GI)
When we eat foods that contain carbohydrates, they are broken down to glucose and this is referred to as blood sugar.
The Glycemic Index is basically a rating system for foods that contain carbohydrates. It measures how quickly a specific carbohydrate when eaten on its own has an impact on your blood sugar levels.
What is a high GI value compared with a low GI value?
A food that is digested and absorbed quickly has a high GI value and causes a rapid increase in blood sugar whereas one with a low GI is digested and absorbed more slowly.
Foods are rated based on the following system :
• Low (55 or less)
• Intermediate (55-70)
• High GI (70 or more)
Most of the time, foods with low GI are considered to be healthier than those with a high GI. Low GI foods discourage sudden spikes in blood sugar levels which in turn can help with weight loss and those with diabetes.
But high GI foods are not all bad and can be useful for those who require a quick source of glucose, such as athletes when competing or during recovery.
The glycemic load (GL)
Whilst you may have heard of the GI before, it’s unlikely you’ve heard of the Glycemic Load (GL).
What the GI index doesn't take into account is the amount of carbohydrate found in a sensible portion of the food, which is where the GL steps in. This measurement looks at the speed at which a food is broken down to glucose and how much carbohydrate there is in each food (and therefore how much glucose will be created and released into the bloodstream).
For example, watermelon has a high GI (glucose released very quickly) but a low GL as the amount of carbohydrate in a portion is small due to its high water content.
It’s a little confusing, but our main point is that not all foods with a high GI are unhealthy and this is where the GL can help.
Making healthy food choices and maintaining a healthy body weight
Blood sugar levels are important because they are linked to hunger and the way we eat. If you have gone a while without eating you will get hungry and your blood sugar levels will fall. When you then consume foods, your blood sugar rises as these are converted to glucose.
High GL foods can cause spikes in blood sugar and produce high levels of the hormone insulin which promotes the storage and inhibits the breakdown of fat (excess glucose is converted to fat for storage).
Low GL foods cause less dramatic spikes and maintain stable blood sugar levels which can help you to control your weight and helps your body to use its fat stores better.
Low GI foods are generally considered to be healthier food choices and are often higher in fibre and protein (such as milk, fruits and vegetables and wholemeal bread) which are considered to keep you feeling fuller for longer as the food is slowly broken down. You will also be controlling the portion sizes that you are eating as you prepare dishes with a low GI rating.
Is this a good diet for those with diabetes?
People with diabetes can eat the same food as anyone else following the guiding principle of a balanced diet. The GL score does follow these principles by encouraging a diet that contains complex carbohydrates (high fibre) plenty of vegetables and lean proteins whilst discouraging the over consumption of foods high in sugar. However, it may be a useful tool for diabetics who need to monitor their blood sugar levels much more closely and ensure less carbohydrates are eaten.