How do GI and GL fit into the metabolism story?
A balanced diet will include predominantly Carbohydrates; however, learning more about the characteristics of specific foods within the Carbohydrate group will help you make better choices.
The GI ranks Carb food and drinks according to their effect on your blood glucose level i.e. the amount of glucose released into the bloodstream two hours after eating a Carb food. The ranking goes from 1 (Low GI) to 100 (High GI). Some Carbs score higher than 100!
Researchers determine GI ratings by measuring foods in isolation based on a consistent serving size. The index can only provide an approximate value because glucose release and absorption can be influenced by many factors such
as dietary fibre, food processing, other nutrients and your individual health status and physiology.
Hot Coals and Firecrackers
It may help to imagine GI as different levels of heat.
Low GI Carbs are like Hot Coals. They smoulder for a long time and burn out very gradually. Hot Coal foods like apples, carrots, grain breads and porridge (rolled oats), keep your tummy satisfied for longer, which helps control appetite throughout the day.
In general, Carbs with a GI value of 55 or less are digested and metabolised more slowly resulting in a gentle rise in blood glucose.
Medium GI Carbs are like a Campfire. They burn a little quicker but the glucose is released into the bloodstream at a rate that does not stress your metabolic processes.
Camp fire foods have a GI rating between 56 and 69 and include foods such as brown rice, sweet potato (boiled) and couscous.
High GI Carbs are like Firecrackers. They burn intensely for a short time and disappear quickly.
Carbs with a GI value of 70 or above, such as white rice, potato and energy drinks, are Firecracker foods. They are processed very rapidly so you will feel hungry much sooner after consuming them.
Firecracker foods, especially those with no associated fibre, cause blood glucose ‘spiking’, which puts a lot of stress on your body.
While investigating GI, you will hear about Glycemic Load (GL), which is another way to measure the effect of Carbs on your blood glucose.
GL is different to GI in that it takes into account both the type (i.e. GI) and the actual quantity of glucose (without fibre and other nutrients) to gain a more accurate prediction of how a specific food might affect your metabolic processing.
GL is determined by multiplying the GI rating of the Carb type by the grams of glucose in the serve, then dividing by 100. GL = GI x grams of glucose ÷ 100
Choosing Hot Coals over Firecrackers whenever possible will help control your appetite and reduce wear and tear on your body.