The glycaemic index (GI) in short is the classification given to a food based on how quickly they raise the glucose level of the blood.

The foods types that are on the glycaemic index are those that contain carbohydrates. Carbohydrate sources include but are not limited to potato, cereals, pasta, bread, rice, vegetables, fruit, yoghurt, chocolates, cakes and of course sugar. 

The glucose levels in your body change when the digestive system breaks down carbohydrates in foods and drinks into simple sugars. Simple sugars are then carried to each cell through the bloodstream. 



Insulin is secreted from the pancreas, which assists glucose in migration from the blood into the cells. Once inside a cell, the glucose is ‘burned’ along with oxygen to produce energy.



The body converts excess glucose from food into glycogen. Glycogen is stored within muscle tissue and the liver. It supplements blood sugar levels if they drop when exercising or when we have gone without food for longer periods of time. (1)

This Glycaemic Index ranks carbohydrate-containing foods based on their effect on blood sugar levels over a period of time. The index ranks these carbohydrates using the following scale from 0-100

• low GI (less than 55)
• medium GI (55 to 70) 
• high GI (greater than 70)
  
   

Factors such as the size, texture, viscosity, and ripeness of a food affect its GI.

GI may also be altered with the addition of fat, protein, soluble fibre, fructose, and lactose. Fat and acidic foods slow the rate at which the stomach empties and slow the rate of digestion, resulting in a lower GI.

Altering a foods state will also affect the glycaemic response it is given. Foods that are blended, boiled, roasted, grilled, cut in to smaller pieces, become more easily absorbed and therefore have a higher GI.

 

Strangely enough, foods that have been cooked and allowed to cool can have a lower GI when eaten cold than when hot.

 

Although there is no supporting evidence that a Low GI diet will result in weight loss, eating a diet made from foods with a low GI may assist in cutting calories in your daily intake through suppressing cravings by balancing blood-sugar levels.

 

Foods with a GI lower than 55 raise blood sugar slightly, while those in the 55 to 70 range raise it a little higher; carbohydrates with a GI of more than 70 send it soaring.

 

However, you need to take caution when looking in to a low GI diet. Chocolate cake may have a lower GI than wheat bread, but the bread is obviously better for you. What needs to be taken in to account is that the chocolate cake has far more fat, sugar, and calories than the white bread, as well as far less fibre.

 

The key to the low GI diet is to replace as many high-GI foods in your diet with healthy low-GI options. (2)

• Include protein and fat whenever you eat a high-GI food.
• Reduce the blood-sugar impact by pairing a higher GI food with a lower GI food.
• Substitute in at least one healthy low-GI food for each meal.
• Choose whole grains over refined.

Control portions. Bigger meals always stimulate a higher blood-glucose response than smaller ones,

 

 

Low Glycaemic Index Foods

Foods with a GI Score Lower Than 55

Food	Serving Size	Glycaemic Index
Apple	1 medium	38
Banana	1 medium	52
Bread, whole grain	1 slice	51
Carrots	1 medium, raw	47
Cereal - All-Bran	1/2 cup	30
Cherries, fresh	18	22
Iced Chocolate cake	100g slice	38
Grapes - green, fresh	3/4 cup	46
Grapefruit	1/2 medium	25
Grapefruit juice	1 cup	48
Lentils, brown	3/4 cup, cooked	29
Oats	1 cup	49
Orange	1 medium	42
Orange juice	1 cup	53
Pasta, spaghetti	1 1/2 cups, cooked	38
Peas, green, frozen	1/2 cup, cooked	48
Rice, brown	1 cup, cooked	50
Sweet potato	125 Grams, cooked	44

                   

Medium Glycaemic Index Foods

Foods with a GI Score 55 to 70

Food	Serving Size	Glycaemic Index
Basmati rice	1 cup, cooked	58
Bread, rye	1 slice	58
Bread, white	1 slice	70
Corn	1/2 cup, cooked	60
Honey	1 tablespoon	55
Oats, instant	1 cup	66
White rice, long-grain	1 cup, cooked	61

                  

High Glycaemic Index Foods

Foods with a GI Score Higher Than 70

Food	Serving Size	Glycaemic Index
Cereal, Bran Flakes	1/2 cup	74
Cereal, Corn Flakes	1 cup	92
Doughnut	50 Grams	76
English muffin	40 Grams	77
Fries - frozen, heated	30 fries	75
Gatorade	1 cup	89
Microwave Popcorn	1 1/2 cups	72
Potato, baked	1 medium	85
Potatoes, mashed	1 cup	73
Rice cakes, white	3 cakes	82
Rice - instant, white	3/4 cup, cooked	87
Watermelon, fresh	100 grams	72

REFERENCES 



1. https://www.betterhealth.vic.gov.au/ low GI diets



2. http://www.fitnessmagazine.com/ Glycaemic Index