So
what's the GI?
The
mass of facts and figures that adorn food labels can be cryptic
and confusing. We unravel the mysteries of the Glycemic Index.
The
Glycaemic Index (GI) is a measure of how much glucose circulates
in the blood during two hours after a standard amount of food
is eaten. This is then graded on a scale of one to 100 with a
standard reference food, usually glucose.
Foods with a score (GI) of 70 to 100 are regarded as high GI foods.
These raise blood glucose levels rapidly and are quickly broken
down through normal digestion. Foods with high GI include white
bread, potatoes, instant rice, and cornflakes.
Foods with a GI of 50 to 70 are moderate GI foods and include
wholemeal bread and Weet-bix.
Foods with a score of less than 50 are low GI foods and include
multigrain bread, sweet potato, pasta, Basmati rice, most fruits
and most dairy products.
Low GI foods raise blood glucose levels slowly and prevent the
highs and lows seen with high GI foods.
Origins
GI
was developed for diabetics as a method of choosing foods that
would control blood glucose levels better.
The method has liberalised diabetic diets, and allows for some
high-sugar foods to be consumed. There are many factors that govern
the glycaemic index.
These include the type of starch and fibre, particle size, fat,
maturation of the fruit or vegetable (sugar type) and cooking
method/ time. Some low GI foods are high in fat, as fat slows
the emptying of food from the stomach.
Foods high in protein (slows the digestion of starch) can also
affect GI values. Mixed meals with a variety of carbohydrates,
fats and proteins have a lower GI compared to a meal that is predominately
carbohydrate.
The rule is to consume one low GI food at each meal. This allows
for better control of blood glucose levels and consequently insulin
levels.
Manufacturers have been encouraged to adopt the low GI logo for
placement on products making it easier to identify the GI value
of foods.
Weight
Watchers
There
is little evidence that a low GI diet can assist with weight reduction.
Low GI foods are usually more filling, a substantial advantage
when trying to reduce weight.
The low GI diet allows high fat foods such as cheese (GI = 0)
and chocolate (GI = 43) to be eaten, as they have minimal carbohydrates.
They are both very high in fat. Weight loss is achieved by eating
less kilojoules than the energy that is expended.
This may be difficult on a low GI diet, particularly if you choose
the higher fat (and usually more appealing) low GI foods. Portion
control is still important when controlling weight.
Reducing high fat foods is also necessary for reducing weight.
The
bottom line
The
GI is not a guide to “good” or “bad” foods and should not be substituted
for general guidelines on healthy eating.
It is still important to increase the intake of fruit and vegetables,
wholegrain breads and cereals, moderate the intake of lean meats,
chicken, other protein foods and low fat dairy products and minimise
fats, sugars and alcohol.
The Glycaemic index is basically a guide to choosing better sources
of carbohydrates and should be used for its intended purpose.
For more information read The GI Factor by J. Brand Miller or
visit www.glycaemicindex.com
