In our last post, we discussed the Glycemic Index (GI), which is a measure of how quickly the carbohydrates you consume are digested and broken down into glucose. Glucose is the basic “fuel” for all our bodily functions.
The GI ranks or scores carbohydrate foods from 0 to 100, and in general, foods scoring below 57 are considered “low” GI, foods between 57 and 69 are considered “medium” and foods scoring 70 to 100 are considered “high” GI foods (typically the least healthy carbohydrates).
Raw carrots (GI= 47)
Raw Apple (38)
Low-fat yogurt (33)
Brown Rice (55)
Medium GI Examples:
Raw Pineapple (59)
White spaghetti, boiled 20 minutes (61)
White rice (64)
High GI Examples:
White Bread (70)
For a more complete list, in Portuguese, click here. The most famous “reference” laboratory worldwide for GI testing is at the University of Sydney (Australia), and most any food that has been tested can be searched here (only in English).
Some cautions and controversies regarding the GI
The GI values are not so precise. It depends on the exact type of a food, for example, different varieties of potatoes can vary widely; there is much variation in fruits, for example, the riper the fruit usually the higher the GI.
The preparation of a food changes the GI. Usually the more processed the food, the higher the GI. This is because processing makes the food easier, thus quicker, to digest (and form sugar in your system). How a food is cooked may affect the GI. For example, notice in the list above spaghetti boiled for 20 minutes has a GI of 61, but if boiled for only 5 minutes, its GI is only 38.
Different people have different insulin responses to the same foods. Some people digest quickly one food and a family member could have a much different response. The values you read in charts are averages of many people. Your individual GI score for a food could be different!
You can’t just look at the GI of a carbohydrate if you are trying to lose weight. You must also consider the amount of the food consumed, and the calories involved. For example, if you only look at the GI scores of a medium sized apple (38), versus peanuts (14), you might conclude that eating peanuts as a snack would be better for you than the apple. Not true. This is because the apple, weighing 138 grams, has about 72 calories, but a 110 gram bag of peanuts has over 500 calories! So clearly, the apple, even though it has a higher GI score, would be the better choice.
The GI is interesting and worth knowing about, and it is good to be somewhat knowledgeable about how different foods are converted into sugar in your system. It is advantageous to avoid sudden surges in your blood sugar level, and good to avoid chronically high insulin production from your pancreas.
Avoiding spikes in blood glucose will help avoid the sharp drops in glucose that inevitably follows these surges, which lead to quickly getting hungry again, with the risk of overeating.
In general, yes, if you are choosing two foods that weigh about the same, you are better off choosing the food with the lower GI score. But don’t depend solely on GI. Also look at the big picture. The GI is just one indicator of a food’s overall nutritional value. For more information, read some of the highlighted links in this post, and here are some hints consistent with a low GI diet:
Eat breakfast cereals based on oats, barley and bran
Choose breads with whole grains, or stone-ground flour
Eat fewer potatoes
Eat plenty of high-fiber fruits and vegetables
Avoid large portions of rice, pasta and noodles; chose organic when possible, and cook pasta less rather than more!
Esta postagem também está disponível em: Portuguese (Brazil)