Glycemic Index & Glycemic Load
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Managing blood sugar levels is an important part of improving our metabolic health. If our blood sugars remain elevated for too long, this can impact the body’s ability to effectively use energy; with prolonged elevated levels increasing the chances of conditions such as metabolic liver disease and type 2 diabetes.
When it comes to focusing on blood sugar control, carbohydrate foods are the primary group to focus on. Carbohydrate foods are quickly absorbed by the body and, depending on the type of carbohydrate food can lead to sharp increases in blood sugar levels. Ranking systems like the Glycemic Index (GI) and Glycemic Load (GL), were created as additional tools to inform how individual foods may impact blood sugar response.1
Let’s review both GI and GL, how they work, their strengths and limitations, and what steps you can take to potentially use these tools as part of your journey to better health.
What is the Glycemic Index (GI)?
The Glycemic Index (GI) is a ranking system that ranks individual foods on a 0 to 100 scale based on how quickly each food may impact blood sugar. A food categorized as “high” (ranking > 70) may lead to a sharper spike in blood sugar response, whereas a food categorized as “low” (ranking 55 >) results in a slower and more steady blood sugar response after eating the food.2
GI is a pretty simple way to help folks understand how carbohydrate foods might impact blood sugar, but, there are a few limitations. GI isn’t able to factor in different preparation methods (i.e boiling vs. baking), different brands of the same type of food, the quality of the carbohydrate food, or how each person’s blood sugar response may differ for any given food.2
Regardless of the limitations of GI, multiple scientific studies support following a low glycemic index Mediterranean diet pattern for patients with metabolic liver conditions.3-5 The overall goal of this diet pattern is to reduce how much refined and ultra-processed carbohydrate is in your diet (which are also high GI foods) in order to improve blood sugar and overall metabolic health.
Glycemic Load (GL)
Glycemic Load (GL) is based on the amount of grams of carbohydrate (or specific serving size in grams of carbohydrate) of the food. “Low” GL is <10 and “high” >20.2
Similarly to GI, GL also has some limitations as it doesn’t reveal how each person’s individual response to a given food, and doesn’t look specifically at carbohydrate quality. GL does, however, focus on grams of carbohydrate (or portion of the carbohydrate food) versus perceived, short-term blood sugar response.
Universal Carbohydrate Quality Score or Index
Determining a universal carbohydrate quality score or index in order to better guide us regarding carbohydrate foods is underway.6,7 But, this type of tool or guide is not yet available for use - more to come from nutrition scientists in the future!
Overview of Foods Categorized as Low and High GI and GL
In summary, GI and GL are both tools that can help you further dial in your diet and manage blood sugar. Considering complex over simple carbohydrates can be effective in supporting blood sugar management since the amount of fiber in a food is also important to consider. And, choosing low GI and GL foods as part of your diet plan may be another beneficial step that leads to better health.
Low GI & GL foods:7,8
- Non-starchy veggies
- Greens, carrots, broccoli, bell peppers
- Starchy veggies
- Beans (like chickpeas), lentils
- Fruits
- Berries (like strawberries, blueberries), apples, pears
- Dairy
- Plain yogurt
High GI & GL foods:7,8
- Fried starchy veggies
- French fries, fried potatoes
- Refined, white flour-based products
- White bread, pasta,
- Desserts, pastries
- Sugary breakfast cereals, granola
- Snacks like chips and crackers
- Dairy
- Sweetened yogurt or flavored milk
*References available with PDF download.*