Glycemic Index (GI) is a numerical index that ranks carbohydrates based on their rate of glycemic response (their conversion to glucose within the human body). GI uses a scale of 0 to 100, with higher values given to foods that cause the most rapid rise in blood sugar. Pure glucose serves as a reference point and is give a GI of 100.
Some foods raise blood sugar more than other which means they have a relatively high GI compared to other food of equivalent amount. Our bodies respond to high blood sugar with a high dose of insulin (negatively feedback mechanism) - a hormone which takes sugar out of the blood stream and delivers it to the cells. High level of insulin (besides it makes you craving for more food and fucking sleepy when you want to study) can enhance the risk for a number of undesired health conditions, like Metabolic Syndrome and Type II Diabetes,
As you can see from the figure above, meals containing carbohydrates-rich foods with a high GI tend to give a more rapid and higher rise in blood glucose then meals with a low GI. Moreover, the low GI meal result in a moderate increase in blood glucose that is prolonged compared to that seen after a meal with a high GI food, thus providing a steady and continuous supply of energy for the body.
How to lower the GI value of your meal
- Combining high GI foods with low GI foods
- High protein content
- High fiber content
- Lemon (2 tablespoon of lemon may reduce GI of a meal by 30%)
- Fat (however it isn't the best way for decreasing GI if you are looking for a low calorie solution).
We don't have to worry too much about consuming high GI food (especially you're an undergraduate who is trying to balance your university workloads, your nutrition and workout), because combining it with low GI foods levels out the overall GI value and results in an average GI value. The overall GI value of different foods in a meal is what really matters. For example, eating potato (high GI) with salad (low GI) lowers GI to an average value, so it is better to eat them together rather than eating potato in itself. Another good solution is to consume high GI carbohydrates with proteins (low GI) in order to decrease the GI of our meal.
Make sure you're clear that even though you're consuming low GI foods, it doesn't mean that you are in the correct path to weight loss provided the total calories consumed is less than the total calories used.
Why Is Glycemic Index Important?
Your body performs best when your blood sugar is kept relatively constant. If your blood sugar drops too low, you become lethargic and experience increased hunger. If your blood glucose level goes too high, your brain signals your pancreas to secrete more insulin and it will bring your blood sugar down, by primarily converting the excess sugar to stored fat. Also, the greater the rate of increase in your blood sugar, the more chance that your body will release an excess amount of insulin, and drive your blood sugar back down too low.
Therefore, when you eat foods that cause a large and rapid glycemic response, you may feel an initial elevation in energy and mood as your blood sugar rises, but this is followed by a cycle of increased fat storage, lethargy, and more hunger!
Although increased fat storage may sound bad enough, individuals with diabetes (diabetes mellitus, types 1 and 2) have an even worse complication. Their bodies inability to secrete or process insulin causes their blood sugar to rise too high, leading to a host of additional medical problems.
Should All High-GI Foods be Avoided?
For non-diabetics, there are times when a rapid increase in blood sugar (and the corresponding increase in insulin may be desirable. For example, after strenuous physical activity, insulin also helps move glucose into muscle cells, where it aids tissues repair. Because of this, it is recommended to consume high-GI foods immediately after exercise to speed recovery
Also, it's not Glycemic Index alone that leads to the increase in blood sugar. Equally important is the amount of the food that you consume. The concept of glycemic index combined with total intake is referred to as "Glycemic Load".
How Glycemic Load (GL) Improves the Glycemic Index (GI)
GI is calculated based on food food servings with 50g of carbohydrate and those serving sizes are nt the amount a person might normally eat, thus the concept of the glycemic load (GL) was created.
The formula for calculating glycemic load is as shown below:
Example:
- Spaghetti (GI= 40): 1 cup contains 52 grams of carbohydrate. The glycemic load of spaghetti is : (40 X 52)/100= 20.8
- Apple (GI=40): 1 medium size apple contains 15 grams of carbohydrate. The glycemic load of an apple is : (40 X 15)/100= 6
This shows how a high GI food can have a low GL in the amounts normally eaten.
Low -GI foods may be a good choice before endurance sports, while high-GI foods could aid recovery after strenuous participation in any activity.
Conclusion:
GI and GL have equally important influence on how fast the food is digested, thus affecting our blood sugar in our body. We must also be aware that there are numerous factors that comes into play when affecting the total GI of our meal, hence don't be that person who feels that it's the end of the world when he/she could only have white rice instead of their brown rice. Moderation and Improvisation is key.
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