Glycemic Index Basics
The glycemic index (GI) is a ranking from 0 to 100 assigned to foods. A food’s ranking on the glycemic index represents the extent to which its respective carbohydrates raise blood sugar (glucose) levels two hours after consumption.
The Glycemic Index and Your Body
Carbohydrates have the most profound effect on blood sugar (glucose) and insulin levels.
Foods with a high GI are those which the body rapidly digests, absorbs and metabolizes. They result in marked fluctuations in blood sugar levels, earning a score of 70 or above.
In contrast, foods with a low GI are those which the body more slowly digests, absorbs, and metabolizes. They produce smaller fluctuations in blood glucose and insulin levels, earning a score of 55 or below.
Diabetes and the Glycemic Index
While there is no standard meal plan that works universally for all people with diabetes, a low GI diet is more conducive to long-term health. Low GI foods benefit people with both Type 1 and Type 2 Diabetes – they make you feel fuller, and help control appetite. The glycemic index is an especially helpful tool for athletes looking to consume the right type of carbohydrates both before and after exercise.
How to Plan a Low Glycemic Diet
A low GI diet substitutes high GI foods for low GI alternatives. Try to prepare meals using fresh, unprocessed ingredients like vegetables, fruits, wholegrains, fish, nuts, and pulses.
A balanced diet may include, but is not limited to:
- Bread, such as wholegrain, multigrain, rye, and sourdough varieties
- Breakfast cereals, such as porridge (with rolled oats), bircher muesli, and All-Bran
- Fruit, such as apples, strawberries, apricots, peaches, plums, pears, and kiwi
- Vegetables, such as carrots, broccoli, cauliflower, celery, tomatoes, and zucchini
- Legumes, such as lentils, chickpeas, baked beans, butter beans, and kidney beans
- Grains, such as quinoa, barely, pearl couscous, buckwheat, freekeh, and semolina
- Dairy, such as milk, cheese, yogurt, custard, and dairy alternatives such as soy milk, and almond milk.
Low GI Diet – Things to Know
When planning a low GI diet, there are a few important things to keep in mind.
All foods are not on the glycemic index
First, not all foods contain carbohydrates, and so not all foods are assigned a GI level. For example, foods like beef, chicken, fish, eggs, fats, oils, herbs, and spices are absent from GI lists.
A food’s GI ranking can change
Additionally, there are a number of factors that influence the GI of a food or meal. The riper the fruit, for instance, the higher the GI level. Whereas an unripe banana has a GI of 30, an overripe banana has a GI of 48.
Preparation and cooking methods similarly effect GI levels. The longer a food is cooked, the higher its GI.
The diabetes diet need not be limited to low GI foods
People with Type 1 and Type 2 Diabetes need not limit their diets to low GI foods. The effect of low GI foods in one meal carries over to the next meal, lowering its glycemic impact. For this reason, experts recommend that people include at least one low GI food per meal.
Glycemic Index Resources
For many, low GI foods can be an important part of managing their diabetes. Understanding the glycemic index allows people with Type 1 and Type 2 Diabetes to facilitate long-term health by choosing the eating patterns that best align with their values, preferences, and treatment goals.
Still, a low GI diet provides certain challenges:
- It can be difficult to calculate a food’s glycemic content
- The GI does not always reflect the healthiness of a food
- The GI does not account for the quantity of carbohydrates consumed.
We recommend further reading to become more familiar with the glycemic index. These are some useful resources:
- Healthline: A Beginner’s Guide to the Low Glycemic Diet
- Mayo Clinic: Glycemic Index Diet: What’s Behind the Claims
- Diabetes Canada Nutrition Therapy Guidelines
- University of Sydney: Glycemic Index Search
- Healthline: Why Refined Carbs are Bad for You
- Harvard Medical School: A Good Guide to Good Carbs: The Glycemic Index
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