Glycaemic Index (GI) or Load (GL) ?

The Glycaemic Index (GI) : was devised as a ranking system to show how quickly a given carbohydrate can feed glucose into the blood. It was originally devised to help diabetics to manage their blood glucose levels, but has since become of increasing value to people engaged in weight management and regular training.

Glycaemic index and research:

- long term consumption of a diet with a high glycaemic load , has been shown to be a significant independent predictor of the risk of developing Type II diabetes and cardiovascular disease

- recent studies have shown that diets with a low glycaemic index may help protect against the development of obesity and colorectal cancer

- diets with a predominance of low glycaemic foods have been shown to be more satiating than high glycaemic diets, and can help in the treatment of obesity

Main factors influencing the speed of entry of carbohydrate into the blood:

- amount of carbohydrate eaten

- the presence of fat in the meal. Fat the strongest inhibitor of gastric emptying

- the presence of protein in the meal. Protein also a gastric inhibitor

- the presence of fibre in the meal delays gastric emptying - the presence of soluble fibre slows the absorption of glucose into the blood

- cooking methods, heat breaks down saccharides into simpler molecules

- the ripeness of fruit. As a banana ripens, enzymes become active and begin to break down the polysaccharides into smaller saccharide units

- food preparation, bread has a higher GI than pasta, even though they are both derived from wheat.

Glycaemic index range: High :above 85, moderate: 60-85, low: below 60.

Glycaemic Index (GI) or Load (GL) ?

Although there is valuable mileage in the use of the glycaemic index, one of its problems is that the rate that glucose is released into the bloodstream does not tell us everything about the needed response from the pancreas. If we fed someone 10g of pure glucose the rate of response would be a GI of 100, whereas if we fed the same individual 20g of glucose the GI would still be close to 100, but there is twice as much carbohydrate to be removed from the blood into the cells. The system that indicates the amount of carbohydrate that is contained within a food source in conjunction with its glycaemic index rating is called the glycaemic load. Therefore it identifies both the quantity and quality of a carbohydrate source.

Glycaemic load range: high: 20 and above, moderate: 11-19, low: 10 and below.

High GI & GL diets increased risk of diabetes type 2 and CHD.

Lower GI & GL diets promote satiety and help with weight management. Watermelon has a GI of 72, but has a very small amount of carbohydrates per 100g, indicating a low glycaemic load ( 4 ) , so the effect on blood glucose will be minimal. A bagel has the same GI of 72, but contains a much larger amount of carbohydrates per 100g, resulting in a very high glycaemic load ( 25 ), over 6 times as much! Both foods will raise blood sugar at the same rate, but the bagel will provide a much larger response, whilst the watermelon will provide a much smaller response.

Food Recommendations:

Avoid :

- white sugar, syrups

- white flour, rice

- white bread, pastries, cakes, biscuits

- carbohydrate content in pre-packed meals

- sweets and confectionery

- soft drinks, cordial, cheap fruit juices

- processed fruit or vegetables

- high glycaemic loads.

Advise :

- wholegrain products