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There Is No “Sugar High”, The Health & Science Behind the Glycemic Index

There Is No “Sugar High”, The Health & Science Behind the Glycemic Index

Published: 09/24/2012 by Tristin Brisbois, PhD Canadian Sugar Institute

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It seems everywhere you look there is a new “diet” book or article telling us what not to eat. Low carbohydrate diets claim to be the secret to weight loss. In fact, carbohydrates (starches and sugars) are our most important source of energy and Health Canada recommends they make up 45-65 per cent of our daily calories. A variety of foods are high in carbohydrates, such as breads and cereals, milk products, fruits, starchy vegetables, and sweets. All carbohydrates are broken down by the body into sugars (e.g., glucose) that enter the blood stream. The glucose in the blood (or blood sugar) is used for energy by the body, especially by the brain and muscles.

Alongside low carbohydrate diets has emerged a growing interest in the glycemic index (GI). This is a scale that ranks carbohydrate-rich foods based on how much they increase blood glucose levels two to three hours after eating. The GI uses a numbering system to label foods as low GI (less than 55), medium GI (55-70) or high GI (more than 70) compared to glucose, which is given a value of 100. Foods with a low GI are digested slower and raise blood glucose less than high GI foods. Examples of low GI foods are pumpernickel bread, sweet potato, barley, and oatmeal. Medium GI foods include whole wheat bread, basmati and brown rice, and popcorn. High GI foods include white bread, bagels, french fries, and pretzels.

It is often mistakenly believed that eating sugar-rich foods causes a large rise in blood glucose followed by an extreme low, causing fatigue and food cravings. The idea of a ‘sugar high’ followed by a ‘sugar crash’ is actually a myth. Sugar (sucrose) is a medium GI food, and so does not cause a spike in blood glucose.

In healthy people, the body regulates blood glucose and keeps levels within an acceptable range. People with diabetes must manually control their blood glucose, and the GI index was created to help do so. The Canadian Diabetes Association suggests that people with diabetes choose low and medium GI foods more often than high GI foods. However, it is important to recognize that the GI scale is not perfect. For instance, fat, fibre and protein as well as the acidity of foods all slow the release of glucose into the blood stream, lowering a food’s GI. Preparation can also change your food: pasta cooked “al dente” (tender yet firm) has a lower GI than pasta cooked until very tender. So far there is no consensus on the overall health benefits of a low GI diet, so the best dietary advice is still to follow Canada’s Food Guide.

So are Canadian children following Canada’s Food Guide? According to the Canadian Community Health Survey (conducted in 2004), most Canadians are meeting their dietary requirements. However, two in 10 children (aged four to eight years) and three in 10 adolescents (nine to 18 years) have energy intakes that exceed their needs. Fibre, fruit and vegetable intakes are also low. Fruits and vegetables lower your blood pressure, risk of eye, heart and digestive issues, and help curb your appetite. Fibre has been linked to reduced likelihood of diabetes, heart disease and obesity! Both are a wonderful addition to your diet!

Although many Canadians’ diets could use help, the bigger issue is physical inactivity. In 2007, Statistics Canada, in partnership with the Public Health Agency of Canada and Health Canada, launched the Canadian Health Measures Survey. Results showed that only seven per cent of children and adolescents were meeting the physical activity guidelines of 60 minutes of activity at least six days a week (15 per cent of adults met the guidelines). So get out there! Exercise increases your energy, decreases stress, and helps prevent Type 2 diabetes, cancer, and heart disease. All that from riding your bike, going to the park, or dancing? Great! 


Canadian Sugar Institute 

The Eat Well and Be Active Educational Toolkit 

Health Canada Food & Nutrition


"Reprinted with permission from Tristin Brisbois, PhD Canadian Sugar Institute"