Chapter 4. Carbohydrates

Glycemic Response

A Carbohydrate Feast

You are at a your grandma’s house for family dinner and you just consumed pork, white rice, sweet potatoes, mac salad, chicken long rice and a hot sweet bread roll dripping with butter. Less than an hour later you top it off with a slice of pie and then lie down on the couch to watch TV. The “hormone of plenty,” insulin, answers the nutrient call. Insulin sends out the physiological message that glucose is abundant in the blood, so that cells can absorb it and either use it or store it. The result of this hormone message is maximization of glycogen stores and all the excess glucose, protein, and lipids are stored as fat.

A typical Canadian Thanksgiving meal contains many foods that are dense in carbohydrates, with the majority of those being simple sugars and starches. These types of carbohydrate foods are rapidly digested and absorbed. Blood glucose levels rise quickly causing a spike in insulin levels. Contrastingly, foods containing high amounts of fiber are like time-release capsules of sugar. A measurement of the effects of a carbohydrate-containing food on blood-glucose levels is called the glycemic response.

Glycemic Index

The glycemic responses of various foods have been measured and then ranked in comparison to a reference food, usually a slice of white bread or just straight glucose, to create a numeric value called the glycemic index (GI). Foods that have a low GI do not raise blood-glucose levels neither as much nor as fast as foods that have a higher GI. A diet of low-GI foods has been shown in epidemiological and clinical trial studies to increase weight loss and reduce the risk of obesity, Type 2 diabetes, and cardiovascular disease.[1]

Table 4.1 The Glycemic Index: Foods In Comparison To Glucose

Foods GI Value
Low GI Foods (< 55)
Apple, raw 36
Orange, raw 43
Banana, raw 51
Mango, raw 51
Carrots, boiled 39
Taro, boiled 53
Corn tortilla 46
Spaghetti (whole wheat) 37
Baked beans 48
Soy milk 34
Skim milk 37
Whole milk 39
Yogurt, fruit 41
Yogurt, plain 14
Icecream 51
Medium GI Foods (56–69)
Pineapple, raw 59
Cantaloupe 65
Mashed potatoes 70
Whole-wheat bread 69
Brown rice 55
Cheese pizza 60
Sweet potato, boiled 63
Macaroni and cheese 64
Popcorn 65
High GI Foods (70 and higher)
Banana (over-ripe) 82
Corn chips 72
Pretzels 83
White bread 70
White rice 72
Bagel 72
Rice milk 86
Cheerios 74
Raisin Bran 73
Fruit roll-up 99
Gatorade 78

For the Glycemic Index on different foods, visit

The type of carbohydrate within a food affects the GI along with its fat and fiber content. Increased fat and fiber in foods increases the time required for digestion and delays the rate of gastric emptying into the small intestine which, ultimately reduces the GI. Processing and cooking also affects a food’s GI by increasing their digestibility. Advancements in the technologies of food processing and the high consumer demand for convenient, precooked foods in Canada has created foods that are digested and absorbed more rapidly, independent of the fiber content. Modern breakfast cereals, breads, pastas, and many prepared foods have a high GI. In contrast, most raw foods have a lower GI. (However, the more ripened a fruit or vegetable is, the higher its GI.)

The GI can be used as a guide for choosing healthier carbohydrate choices but has some limitations. The first is GI does not take into account the amount of carbohydrates in a portion of food, only the type of carbohydrate. Another is that combining low- and high-GI foods changes the GI for the meal. Also, some nutrient-dense foods have higher GIs than less nutritious food. (For instance, oatmeal has a higher GI than chocolate because the fat content of chocolate is higher.) Lastly, meats and fats do not have a GI since they do not contain carbohydrates.

More Resources

Visit this online database to discover the glycemic indices of foods. Foods are listed by category and also by low, medium, or high glycemic index.

  1. Brand-Miller J, et al. Dietary Glycemic Index: Health Implications. J Am Coll Nutr. 2009; 28(4), 446S–49S. Accessed September 27, 2017.


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