When looking at the foods we eat you may have come across the term GI or 'Glycemic Index'. The term is becoming increasingly more common on foods with a push toward eating a diet containing a higher percentage of foods classed as 'Low GI'. But what does it all mean and how should it influence our eating habits?
Glycemic Index relates specifically to carbohydrate and is a measure of how quickly these carbohydrates spike our blood sugar after eating, fats and proteins do not have a GI. Carbohydrates come in a huge variety of forms from simple sugars to complex starches however the role of digestion is to break them all down to their simplest form- glucose, thus all have different rates at which they are processed by the body. Once broken down to glucose, it can enter the blood stream as blood glucose, more commonly referred to as blood sugar. All carbohydrates are given a number on the GI scale from 1 - 100+ with glucose being the standard, rated 100. The higher the number the faster this food is digested by the body. It is important to remember that 100 while being the GI for glucose, is not the upper limit of the GI scale, some foods such as jasmine rice have a rating over 100! Meaning they get into your system quicker than glucose itself, in the instance of jasmine rice it has a GI of 109, this really shows the importance of knowing the GI of basic foods.
So, now that we understand how GI works - what makes low GI foods more preferential?
We must remember that carbohydrates are energy and that if not burned off through exercise they will be stored, in this case if we eat a meal containing a lot of high GI foods this provides an instant release of energy which must then be burned off quickly to prevent storage as fat if our carbohydrate stores (muscle and liver) are full. This means low GI foods make weight management far easier.
Low GI foods give a slow, steady release of energy providing consistent fuel throughout the day and making them easier to burn off. This slow steady release additionally helps low GI foods keep blood sugar levels constant. The sudden spike in blood sugar from high GI foods is met with an insulin response which in turn moves glucose out of the blood leading to a 'crash' in energy. Ever felt tired or sleepy after a big meal? This is why.
Some examples of low and high GI foods include:
Low GI (less than 55) - Pasta, Milk, Soy products, Porridge, Lentils, Grainy Bread
Medium GI (55 to 70) - Honey, Basmati rice, Wholemeal Bread, Sweet potato
High GI (greater than 70) - White bread, Short grain rice, Cornflakes, Rice crackers
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