Glycaemic Index: Is it just a number?
We all know that the food we eat affects our body in different ways. It is no surprise that a healthy diet has powerful benefits for our physical, mental and social wellbeing. The carbohydrates, fat and proteins in the food we eat supply energy or fuel that the body requires to function normally. Carbohydrates, such as sugar and starch are readily broken down into glucose, in our stomachs and then absorbed into the blood stream. Glucose is the body’s principal energy source that is needed by all the cells and organs in our body. In order to determine how efficiently food works its way through our digestive system to affect our blood sugar, scientists developed the Glycaemic Index (GI).
What is Glycaemic Index?
Glycaemic Index (GI) is a number that ranks carbohydrates based on their rate of glycaemic response, that is the conversion to glucose within the human body. Glycaemic Index uses a scale of 0 to 100, with higher values given to foods that cause the most rapid rise in blood sugar which can be dangerous especially for those with diabetes. Pure glucose serves as a reference point, and is given a Glycaemic Index (GI) of 100. The lower the number the lesser the impact will be on your blood sugar. In a scale of 1 to 100, low glycaemic index food have a value less than 55, while medium is 56-69 and anything 70 and above is considered as high.One of the major factors that determines the GI value of a food is how refined its carbohydrates are. If the food has been processed most of the carbs would have naturally lost their fibre allowing the body to easily convert it to sugars.
Why is GI important?
GI is important to simply minimize insulin-related problems by identifying foods that have the greatest effect on blood sugar. When the blood sugar drops too low, you become lethargic and/or experience increased hunger. If it is too high, your brain signals your pancreas to secrete more insulin that brings the blood sugar back to normal primarily by converting the excess sugar to stored fat.
Also, the greater the rate of increase in 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 glycaemic 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! Individuals with diabetes have an even worse problem as their body is unable to secrete or process insulin causing their blood sugar to rise too high, leading to a host of additional medical problems.
Should high GI foods
be avoided?
It all depends on your health condition. 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 tissue repair. Because of this, some coaches and physical trainers recommend high-GI foods (such as sports drinks) immediately after exercise to speed recovery. For diabetics, it is advisable to eat low GI foods considering the fact that a spike in blood sugar levels can lead to other health complications.
Glycaemic load (GL)
In real life we do not eat the same amount of the different types of food. For example we will not eat the same amount of sugar as the amount of rice or vegetables. So, it is not the GI alone that leads to the increase in blood sugar. Equally important is the amount of the food that you consume. The concept of Glycaemic Index combined with total intake is referred to as “Glycaemic Load” where it considers the type of carbohydrate in a food and the amount in a typical serving. Thus GL helps you to account for both the quantity and the quality of your carbs at the same time. Less than 10 is low; 11 to 19 is medium and more than 20 is high. Foods with a low GL cause a steadier and lower rise in blood sugar levels while high GL foods cause a faster and higher rise.
Glycaemic load can change
There are various factors that affect the GL of a food. Many of these are similar to those that also influence the GI of a food. These include: the types of sugar and starches in the food, the way it is prepared, its fat, fibre and carbohydrate content, and the serving size. The rate of absorption and digestion of food products also influences the GI and GL. For example small differences in the ripeness of a banana can even double its GL. In addition, when foods are eaten together, for instance when you eat rice together with meat the GL of the food becomes much lower to the GL of the rice itself. Or sprinkle lemon juice on white rice to lower the GL of the rice, or drink lemon water with your meal.
What to eat for a low GL
For a diet with a lower glycaemic load, eat:
More whole grains, nuts, legumes, fruits and vegetables without starch such as melons, citrus fruits, berries, leafy greens, cucumber, zucchini, beans, leeks, tomatoes, avocados (though high in carbohydrates are very low in GI), mushrooms, onions, cabbage, carrots, cauliflower, broccoli etc.
Fewer foods with a high glycaemic index, like potatoes, yams, white rice, and white bread
Less of sugary foods, including candy, cookies, cakes, and sweet drinks
So the crux of the glycaemic story is the closer your food is to the earth you are better off with respect to the glycaemic factor as well as all other factors that constitute healthy eating.