Glycaemic Index

How carbs can impact your blood glucose

The rate at which carbohydrate impacts on blood glucose depends mainly on the amount (carbohydrate load) and to a lesser extent, the type of carbohydrate (glycaemic index).

The Glycaemic Index (GI) is a scale from 1 to 100 that is used to measure how quickly foods that contain carbohydrate raise blood glucose levels. Foods that contain carbohydrate are given a GI value; foods that have little or no carbohydrates such as cheese, meat, fish and eggs will have no GI value.

The diagram above demonstrates how low, medium and high GI foods can affect blood glucose over time.

Carbohydrate foods that break down quickly during digestion raise blood glucose more quickly, and have a higher GI value (greater than 70). Foods that break down more slowly during digestion raise blood glucose more slowly and have a lower GI value (less than 55)

The diagram above demonstrates how low, medium and high GI foods can affect blood glucose over time.

 

Low, Medium and High GI Foods

The table below illustrates the GI value of commonly eaten foods and drinks

	Low GI Less than 55	Medium GI 55 - 70	Higher GI Greater than 70
Breakfast cereals	All Bran, Sultana Bran, muesli, porridge oats	Instant porridge, Weetabix, Shredded Wheat, Special K	Coco Pops, Rice Krispies, Cornflakes, Cheerios
Bread, biscuits, cakes, confectionery	Rye bread, pumpernickel bread	Granary/multi-grain bread, pitta bread, wholemeal bread, crumpet, digestives, rich tea, crisps, chocolate	French stick, white bread, bagel
Potatoes, rice, pasta	Sweet potatoes, noodles, macaroni, spaghetti	New potatoes, boiled potatoes, cous cous, brown rice, basmati	Instant potatoes, baked potatoes, instant rice, french fries, chips
Fruit and vegetables	Apples, grapefruit, grapes, kiwis, oranges, pears, peaches, carrots, green peas	Apricots, mangoes, pineapples, raisins, sultanas, melons	Watermelon, turnip, parsnips
Beans and pulses	Baked, butter, black, kidney beans, chick peas, lentils, nuts		Broad beans
Milk and dairy	Milk, custard, yoghurt	Ice cream

• Low GI foods are not always healthy, for example ice cream, nuts and chocolate all have a low to medium GI but are high in fat and calories. Such items should be eaten in small quantities.
• High GI foods can be a good source of nutrients, for example watermelon, so do not need to be removed just because they have a rapid and large effect on blood glucose levels.
• Focus on the overall GI content of your meal 
• For a healthy, balanced approach to eating, include low fat and low sugar foods with lower GI options as a basis for meals and snacks
• The key is to use the Glycaemic Index in the context of balanced eating. A healthy way to use the GI principles is to incorporate a range of lower GI carbohydrates that are also low in fat and calories into your meals.