The Glycemic Index (GI) ranks food on a scale from 0 - 100 according to the speed and extent to which a food containing 50g of carbohydrate is broken down into blood glucose against a 50g dose of pure glucose. Foods with an index number of 70 or more are considered to be high GI, with an index number between 55-70 as medium GI, and 55 or less as low GI.
Both GI and GL refer to the speed and extent to which carbohydrate from foods is converted into blood glucose by the body. The key difference between GI and GL is that GL takes into account the typical amount of a food consumed in a meal, while GI does not.
When you mix foods together in a meal, this affects the GI – not simply a case of taking the average GI of the individual foods. Adding a low GI food lowers the blood glucose response of the whole meal e.g. adding milk to your cereal reduces the GI of your whole breakfast.
How you cook a food, the degree of processing and the ripeness and variety of a fruit, for example, also affect its GI. Even the structure of the carbohydrate itself influences the GI. For example, processed instant oatmeal has a higher GI than traditional rolled oats used to make porridge. This is because, as a result of the processing, the starch in instant oats is more easily exposed to digestive enzymes, causing it to break down and enter the bloodstream more rapidly.
Harraways porridge products made to recommended serve sizes have been tested and are classified as Green E1.
eMark classifies food based on energy density and how quickly the energy is released into the bloodstream. Energy density is shown by the numbers 1 to 5, which rank food according to their kilojoule content per serve.
All foods and drinks can be classified by an eMark number from 1 - 5. The eMark number indicates energy density, which is the amount of energy (kilojoules) per gram of the food, or per 10mls of the drink.
High energy density foods (4e and 5e) have a larger number of kilojoules in a small amount of the food, and usually contain high amounts of sugar, fat, or both: for example, chocolate, butter, lollipops, and some healthy fats and oils.
For healthy meals and snacks, you should choose mostly 1e and 2e foods, with some 3e and eat 4e and 5e foods in only small amounts.
See how it all works in your recommended eMark meal plan.