What is the Glycemic Index?

What is the Glycemic Index

Over the last 30 years, research into food and blood glucose response has completely changed our carbohydrate classification system. It has been decided that it is impossible to predict the impact certain foods will have on a person’s blood glucose levels.  Instead, groups of people are fed foods with carbohydrates and the response is measured and averaged.

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

Foods with a high GI are absorbed quickly into the bloodstream 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 (as a rule you can 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 quickly. Different types of carbohydrates 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 (hypoglycemia) 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 pains 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 now when to use low GI and high GI foods depending on the level of intensity of your daily activities/workouts, and to generally utilize low GI foods.

Simple Steps to a Low GI Diet


Step No 1 

Start with a healthy, well-balanced, and varied diet based on a good nutrition program. The diet should be relatively low in fats (preferably you should be eating “good” unsaturated fats), and moderate in carbohydrates and protein. The program should be high in fiber 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. Avoiding overly processed (refined grains) white bread and pasta and try to include more whole grains.

Try to change the carbs you eat the most with at least one low GI one. For example, replace potato with sweet potato, use beans or lentils instead of rice, or veggie omelet instead of breakfast cereal. Substituting half of your daily carbohydrates 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. Regular consumption of low GI foods increases the feelings of fullness and satisfaction and can thusly prevent weight gain. Try taking in six small meals a day of healthy low-fat low GI foods to prevent overeating at mealtimes and to keep your energy going strong all day.

Remember, that it is also important to look at the calories in food too. 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 won’t lose as much weight if your calories are still high.

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

Grapefruit (26) Pineapple (66) Cornflakes (80)
Baked Beans (15) Raisins (64) White Bread (100)
Lentils (29) Sweet Corn (59) Brown Rice (68)
Peanuts (13) Potato Chips (54) Watermelon (80)
Soy Beans (15) All Bran (51) Baked Potato (98)

Chicken, beef, fish, eggs, nuts, and avocados contain very little to no carbohydrates. These foods if eaten by themselves will not have much effect on your glucose levels and are very low GI.

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

With a bit of planning and sticking to your diet goals, you can reduce the amount of high GI carb foods you take in and give yourself additional energy and be able to get to and maintain a healthy weight.


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