What is the Glycemic Index?

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Over the last 30 years, research into food and blood glucose response has completely changed our carbohydrate classification system.

It has been learned that it is impossible to predict the impact on blood glucose levels by certain foods, instead people are fed carbohydrate foods and the response measured.

This response is known as the Glycemic Index (GI), it is a measure of how quickly carbohydrate foods are digested and absorbed, and ranks carbohydrate foods according to their impact on blood sugar (glucose) levels: as indicted by elevated blood glucose.

Foods with a high GI are absorbed quickly into the blood stream and cause a rapid rise in blood glucose levels. While foods with a low GI are broken down more slowly over time and keep blood glucose levels more stable (Remember that low is slow!).

Some carbohydrate foods will maintain your energy levels for hours, while some may cause your blood glucose to rise and fall. Different types of carbohydrate can also affect feelings of fullness in the stomach and this can influence hunger and your ability to control your body weight.

Why is the GI important?

When our blood glucose levels are stable we have plenty of readily available fuel for the brain and muscles. If our blood glucose levels drop too low (hypoglycaemia) we feel tired, dizzy and generally unwell. If our blood glucose levels rise too quickly a rapid drop usually follows this.

Include low glycemic index foods in meals and snacks to slow the release of glucose into the bloodstream. A low glycemic index snack a few hours before exercise will help maintain your energy levels for more effective training.

After high intensity exercise (strength training) a high glycemic index snack should be consumed within 30 minutes. This will help to replace energy and start the recovery process.

Low-GI foods take longer to digest and help delay hunger pangs that little bit more and thus promote weight loss. So please choose your carbs carefully as this will lower your insulin levels and burn more fat. The secret is to swap high GI foods with low GI foods.

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Simple steps to a low GI diet.
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Step No 1

Start with a healthy, well balanced and varied diet based on a good nutrition program. The diet should be low in fats, moderate in carbohydrate and protein. The program should be high in fibre and contain a varied amount of foods to provide the required amount of vitamins and minerals.

Step No 2

Look at the type of carbohydrates that you consume during the day. Look at the carbs that you eat the most, as these will have the most dramatic impact on your diet.

Try to change the carbs you eat the most with at least one low GI one. (Replace potato with sweet potato, use noodles instead of rice) By substituting half of your daily carbohydrate from high GI to low GI will result in an overall reduction in the GI of your diet.

Reducing the GI in your diet reduces your insulin levels and increases the fat burning apparatus in your body. Try to reduce the high GI's in your diet by substituting them with low GI's.

Regular consumption of low GI foods increases the feelings of fullness and satisfaction and so prevents weight gain. Try taking in six small meals a day of healthy low fat low GI foods to prevent overeating at meal times and control appetite.

Remember, that it is also important to look at the calories in food to. Rice and bread might be low in fat but when your body is burning the carbohydrates in these foods it doesn't burn as much fat. So if you are on a low fat diet, you wont lose as much weight if your calories are still high.

Have a look at the table below for the different GI food ratings.

Low GI ()
Grapefruit (26) Pineapple (66) Cornflakes (80)
Baked Beans (15) Raisins (64) W/M Bread (72)
Lentils (29) Sweet corn (59) Brown Rice (80)
Peanuts (13) Potato Chips (51) Carrots (92)
Soy Beans (15) All bran (51) Baked Potato (98)

Compare these two menus and try to adjust your diet accordingly.

High GI Menu

Breakfast: 40 Grams of cornflakes with milk. Two slices

of whole meal toast with margarine and jam.

Snack: Two sweet biscuits with a white coffee.

Lunch: Ham and salad whole meal Roll with an apple.

Snack: Four crackers with cottage cheese and chives

Main Meal: Serving of Roast chicken with a large baked

potato and peas. Small piece of cake.

Low GI Menu

Breakfast: 40 Grams of bran with low fat milk. Two slices

of low GI toast (Try Burgen) with margarine and jam.

Snack: Two oatmeal biscuits with a coffee (Low fat milk).

Lunch: Ham and salad Roll (Low GI bread). Soft-serve vanilla

yogurt with toasted muesli sprinkled on top.

Snack: Two bananas.

Main Meal: Serving of Roast chicken with a small baked

potato and peas. Two scoops of low fat ice cream

with half a cup of canned peaches.

Chicken, beef, fish, eggs, nuts, and avocados contain very little or no carbohydrates. These foods if eaten by themselves will not have much effect on your glucose levels and are very low GI. Alcoholic beverages especially wine are also low GI so can be included in your diet but remember to count them in your daily caloric intake.

Low GI foods are ideal for losing weight due to the slow absorption from the gut. Low GI foods also help to keep blood sugar levels more stable and this has an effect on reducing sweet cravings.

Gary Matthews is a fitness trainer from "down under" who has been coaching clients from athletes to bodybuilders for two decades. You may contact Gary directly at [email protected] and visit his website at http://www.maximumfitness.com.