What Is the Glycemic Index? How Does It Affect Our Diet?
About the Glycemic Index
What is the glycemic index? The glycemic index is defined as ‘an indicator of the ability of different types of foods that contain carbohydrate to raise the blood sugar levels within 2 hours’. Simply put, it rates carbohydrates based on how quickly your system absorbs them and what impact they have on blood glucose levels.
The glycemic index (GI) is linked with carbohydrates and not with any other macronutrients such as protein and fat, because sugar or, more technically, glucose, is released into the bloodstream when carbohydrates break down during digestion. Those carbohydrates that break down quickly releasing glucose rapidly into the blood stream have a high GI, whereas, carbohydrates that release glucose slowly are said to have a low GI.
The glycemic index rates carbohydrates on a scale of 1 to 100. Some indices use pure glucose as a reference point with a rating of 100, while others use white bread to measure other carbohydrates against.
Glycemic Index Ratings
Low GI = 55 or below; Medium GI = 56 to 69; High GI = 70 or above
Peanuts - GI 14
Bean sprouts - GI 25
Pizza - GI 30
Lowfat yogurt - GI 33
Apples - GI 38
Carrots - GI 47
Oranges - GI 48
Bananas - GI 52
Potato chips - GI 54
Snickers Bar - GI 55
Brown rice - GI 55
Honey - GI 55
Oatmeal - GI 58
Ice cream - GI 61
Sugar (sucrose) - GI 68
White bread - GI 70
Watermelon - GI 72
Popcorn - GI 72
Baked potato - GI 85
Glucose - GI 100
Meal Planning With the Glycemic Index
When planning your meals for a low-glycemic diet, keep in mind that foods that foods that are rich in color, like most fruits and vegetables, have a low to medium GI rating. White foods and other foods devoid of color, like white potatoes and white bread, are usually in the high-GI spectrum and should be avoided or limited. There are exceptions to the rule. Watermelon, for instance, has a high GI rating despite its vivid pink and green colors.
Opt for low to medium GI cereals such as parboiled rice, brown rice, oat bran bread, whole wheat bread or rye bread. For vegetables, you can consume sweet potato, lettuce, carrot, cabbage, cauliflower, broccoli and peas. Stick to leafy green and salad vegetables since they have no effect on your blood sugar. Choose from red and green lentils, chickpea, or black eyed beans for legumes. When selecting a fruit, opt for apples, pears, citrus fruits and plums – they have low glycemic index. Have some skim milk, low-fat cheese or low-fat yogurt instead of snacking on pretzels or corn chips if you plan on following a low-glycemic diet.
Avoid High GI Foods?
Should you alwayws avoid high-GI foods? No. There are times, especially after a strenuous physical activity, when increase in the blood sugar level may be desirable. You may have noticed that a sports drink (with a very high GI) rejuvenates you quickly after a workout. This is because an increase in the blood sugar implies an increase in insulin release by the body. Insulin then moves the glucose into the muscles’ cells and aids tissue repair.
If you want to partake in foods with a high GI rating, add some acid, like vinegar or citrus juice, to the foods or eat them with other fats or fiber. Each of these slows down the time it takes the body to absorb them, resulting in more stable blood sugars. This could mean sprinkling vinegar on your French fries or dabbing some butter on your baguette, if you choose to eat those foods.
That does not mean that a food with a high GI rating will suddenly become a low GI-rated food, however, and it is always wise to select foods with a low or medium GI whenever possible.
Limitations of Glycemic Index
Although, glycemic index plays an important role in keeping the blood sugar levels stable, it has a number of limitations:
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The glycemic response may differ from person to person. Glycemic response to foods varies depending on the size and weight of the body, blood volume and metabolic rate of a person. Results may also vary within the same person depending on what they ate earlier in the day especially when the interval between the meals is just 2 to 3 hours.
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The GI of the food may be altered by the physical state and ripeness, processing and methods of cooking. Usually the longer you cook a food, the easier it is for the body to break it down resulting in higher spikes in blood glucose. Spaghetti cooked for five minutes, for instance, will normally have a lower GI rating than spaghetti cooked for 15 minuts.
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The GI values do not show the impact of glucose levels in the bloodstream after 2 hours.
