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The Glycemic Index and Why People Talk About It

all about the glycemic index

The glycemic index is a word we have all seen thrown around when discussing low-carb diets. We have all been down the rabbit hole researching what foods have low GI and high GI. This is a standard that we have been told but what is GI?

How Do You Get the Glycemic Index?

The glycemic index was a concept developed by Dr. David J. Jenkins in the early 80’s which was meant to be used as a guideline for food choices for people with diabetes. The concept is used to measure how quickly a type of food causes blood sugar levels to rise. GI ranks food on a scale of 0 to 100 based on 50 grams of carbohydrates minus the fiber when measuring the effect on patient’s blood glucose levels over the next two hours.

Low GI: 1 to 55

Medium GI: 56 – 69

High GI: 70 and higher

What’s the Controversy?

The glycemic index doesn’t consider that people won’t eat 50 grams per serving of certain foods. For example, watermelon has a GI of 72, but you need to eat 50 g which is way more than one serving. This brings up another term Glycemic Load which takes into consideration the number of carbohydrates in a regular serving size. Where GI doesn’t tell you anything about the nutritional information about the food, GL explains the effect of a certain type of food but adds in the serving size.

Glycemic Load = (available carbohydrates (g) * Glycemic Index) / 100

The GL for watermelon is 4 – not bad. The GL is supposed to supplement the GI with more accurate information by including the actual serving sizes and how that specific serving will affect your blood sugar.

Why Does it Matter?

Of course, this isn’t the ONLY thing you should be looking at when switching to a low-carb diet. Calories are important too (concentrating on the quality of calories you’re intaking). The takeaway is that GI does provide an indicator as to how sugar can affect your day to day life, but referencing GL makes us more conscious of what we put into our body based on your personal eating habits. Regardless of whether you’re diabetic or not, glycemic index and glycemic load assists in understanding how foods will affect blood sugar.

Higher intake of low GI foods have shown to improve insulin resistance and glucose levels for people with type 2 diabetes.

Take Away

As more sugar and carbohydrate-filled foods take over our grocery, we must be diligent in our awareness of what we’re putting down on our dinner plate. It’s true; we don’t need to know exactly the GI every food we consume, but GI acts a tool that can be used to reduce your sugar intake. Usually, low GI foods already include foods that should be part of a daily diet with nutritionals that can fit any lifestyle you’re adopting.

Low GI Foods

Cauliflower 15
Strawberry 40
Broccoli 10
Plums 24

High GI Foods

Pretzels 83
Rice Cakes 87
Scones 92
Cornflakes 80

As always, make sure to talk to your doctor when you’re making any dietary changes.


Glycemic index diet: What’s behind the claims. The Mayo Clinic. August 1, 2017

Academy of Nutrition and Dietetics. Nutrition Care Manual. Glycemic index. Accessed  January 16, 2018.

Eleazu, C. O. (2016). The concept of low glycemic index and glycemic load foods as panacea for type 2 diabetes mellitus; prospects, challenges and solutions. African Health Sciences, 16(2), 468–479.

What About Glycemic Load?. Glycemic Index Foundation.

High, Medium and Low GI Foods. The GI Diet Guide.

Glycemic Index and Diabetes. American Diabetes Association. May 14, 2014

Glycemic index of foods: a physiological basis for carbohydrate exchange. Jenkins DJ, Wolever TM, Taylor RH, et al. March 1981.