Nutrition

Understanding the Glycemic Index

Last updated: Mar 01, 2014

 

 

 

The glycemic index (GI) ranks carbohydrate-based foods on a scale from 0 to 100, according to how quickly the foods raise insulin and blood sugar.1 For example, foods with a GI >70 are rapidly digested, absorbed, and cause large fluctuations in blood sugar levels. For these reasons, they are considered foods with a high GI ranking. In contrast, foods with a GI <55 are digested slowly and gradually increase in blood sugar and insulin levels. For this reason, they are referred to as foods with a low GI ranking.

Low-GI foods such as green beans, spaghetti al dente, and apples typically contain more fiber compared with high-GI foods. In addition, low-GI foods are usually not processed or undergo little processing. High-GI foods, on the other hand, are often highly processed, low in fiber, and high in sugar. Cornflakes, pretzels, and instant mashed potatoes are examples of foods with a high GI.1

 

Even foods with a low GI rank can raise blood sugar.
For this reason, people who have borderline high blood sugar levels,
prediabetes, or diabetes
should see a certified diabetes educator for dietary guidance
to help stabilize blood sugar.
 

Why GI Ranking Matters

GI ranking can be helpful for stabilizing blood sugar, maintaining a healthy weight, and reducing risk of diabetes and heart disease. Data show that diets rich in foods with a low-GI ranking improve blood sugar levels by reducing insulin levels and insulin resistance and reducing lipid levels in people with type 1 and type 2 diabetes.2 In addition, foods with a low-GI ranking promote satiety, making it easier to control appetite, reduce meal/snack portions, and limit calories.3 Eating a diet that is rich in low-GI foods also can help lower cholesterol and triglyceride levels, which help reduce risk of heart disease.For these reasons, the World Health Organization (WHO) and Food and Agriculture Organization (FAO) recommend a diet based on low-GI foods to prevent obesity, diabetes, and heart disease.

GI ranking applies to foods when they are eaten alone rather than in combination with other foods. Because meals should include a balance of foods, the effect of a high-GI food should be considered when it is mixed with other foods that help balance blood sugar. A meal that includes green beans, fat-free milk, chicken or fish, and an apple, for example, can help offset the effect of a high-GI food such as a baked potato.

Although GI measures how quickly a food raises blood sugar levels, it is not a measure of nutrition. Some foods with a high GI such as baked white potatoes and watermelon, for example, are considered nutrient-dense, healthy foods when they are included in a well-balanced, low-fat, calorie-conscious diet. On the other hand, foods with a low GI such as certain ice creams and white cake from a mix offer little in the way of vitamins, minerals, and fiber but are high in fat, sugar, and calories.5To maintain good nutrition and a healthy weight, foods such as these should be eaten rarely.

 

GI Ranking for Popular Foods*

 

Low-GI foods

  • Vegetables, including:
    • Red peppers = 10
    • Broccoli = 10
    • Mushrooms = 10
    • Cabbage = 10
    • Green beans = 15
    • Cauliflower = 15
    • Eggplant = 15
    • Raw carrots = 16
    • Tomato juice = 38
    • Cooked carrots = 41
    • Frozen, cooked sweet corn = 47
    • Sweet potatoes = 48
    • Cooked green peas = 51
       
  • Fruit, including:
    • Cherries = 22
    • Plums = 25
    • Peaches = 28
    • Apples = 34
    • Orange = 40
    • Strawberries = 40
    • Pears = 41
    • Grapes = 43
    • Kiwis = 44
    • 100 % apple juice = 47
    • 100 % orange juice = 50
       
  • Breakfast cereal, bread, and grains, including:
    • Pearled barley = 22
    • Whole wheat tortilla = 30
    • Spaghetti = 32
    • Whole wheat bread = 49
    • Brown rice = 50
    • Long-grain white rice = 50
    • All-bran cereal = 50
    • Rolled oats = 51
    • Corn tortillas = 52
    • Quinoa = 53
    • Microwaved popcorn = 55
       
  • Dairy products, including:
    • Fat-free milk = 32
    • Sugar-free yogurt = 23
    • Low-fat yogurt with fruit = 33
    • Soy milk = 44
       
  • Dried beans and peas (legumes), including:
    • Red lentils = 21
    • Green lentils = 30
    • Navy beans = 32
    • Yellow split peas = 32
    • Chickpeas = 42
    • Pinto beans = 45
    • Black-eyed peas = 50
    • Kidney beans = 52

Hi-GI foods to eat sparingly

  • Vegetables, including:
    • Pumpkin = 75
    • Parsnips = 97
       
  • Fruit, including:
    • Watermelon = 80
    • Dates = 103
       
  • Breakfast cereal, bread, and grains, including:
    • White bread = 71
    • Bagel = 72
    • Homemade mashed potatoes = 73
    • Instant mashed potatoes = 80
    • Cheerios = 74
    • Total cereal = 76
    • Cornflakes = 80
    • Waffles = 76
    • Instant oatmeal = 83
    • Instant white rice = 87
    • Baguette = 95
       
  • Snacks and sweets with low nutritional value and a high GI ranking (eat sparingly), including:
    • Donuts = 76
    • Vanilla wafers = 77
    • Pretzels = 83
    • Rice cakes = 87
       
  • Snacks, sweets, and fast/prepared foods with low nutritional value and a low GI ranking to eat occasionally, including:
    • Peanut M & Ms = 33
    • Corn chips = 44
    • Potato chips = 51
    • Snickers candy bar = 51
    • Coca cola = 63
    • Gatorade = 78
    • Pizza Hut Super Supreme pizza = 39
    • Chicken nuggets = 46
    • Hamburger with bun = 58
    • French fries = 75
    • Cheese pizza = 80

*Although GI is not listed on food labels, you can visit the University of Sydney GI database for a reliable GI rankings.

Making the most of GI ranking:

  • Include foods with a low-GI as part of every meal and snack
    • Fill tortillas with lettuce, tomato, pinto beans, and shredded low-fat cheese
    • Snack on raw carrots, cauliflower, or red pepper with hummus
    • Enjoy cooked rolled oats topped with chopped apples or strawberries for breakfast 
    • Replace white rice with brown rice when making a stir-fried meal
    • Make sandwiches with 100 percent whole wheat bread instead of a bagel or white bread
    • Eat plain microwaved popcorn instead of pretzels
    • Make a parfait with low-fat, plain yogurt, kiwi, pears, and oranges for dessert or a snack
    • Fill half your dinner plate with vegetables such as broccoli, peas, and green beans
    • Choose fruit such as cherries or grapes for dessert
  • Consume high-GI foods only rarely and eat small portions of them
  • Eat high-fat, high-sodium foods such as chicken nuggets sparingly even though they have a low GI ranking; substitute grilled or baked chicken strips for more nutrition with fewer calories


 

References

1. The Glycemic Index. The University of Sydney, Australia. http://glycemicindex.com/index.php Reviewed November 2013. Accessed 3-1-14.
2. Glycemic Index and Diabetes. American Diabetes Association. http://www.diabetes.org/food-and-fitness/food/what-can-i-eat/understanding-carbohydrates/glycemic-index-and-diabetes.html Last edited January 2, 2014. Accessed 3-1-14.
3. Papadaki et al. Impact of weight loss and maintenance with ad libitum diets varying in protein and glycemic index content on metabolic syndrome. Nutrition. 2013; 23. pii: S0899-9007(13)00400-0.
4. Mirrahimi et al. The role of glycemic index and glycemic load in cardiovascular disease and its risk factors: a review of the recent literature. Curr Atheroscler Rep. 2014;16(1):381.
5. Kimball M. What is glycemic index? Academy of Nutrition and Dietetics. http://www.eatright.org/Public/content.aspx?id=6442478158&terms=glycemic%20index. 2013. Accessed 3-1-14.

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