Glycemic Index vs Glycemic Load Debate – What Should you Pay Attention to

by on December 14, 2015

Glycemic Index vs Glycemic Load Debate – What Should you Pay Attention to
By Eric and Chris Martinez

We remember a couple years ago when the topic of Glycemic Index (GI) and Glycemic Loading (GL) was as hot as those Golden State Warriors 18 game winning streak.

Truth is, a lot researchers and advocates pushed for the use of the GI and GL because they swore by eating lower GI foods daily it would ensure weight loss, change our body composition, and better our overall health.

There are many myths out there regarding both GI and GL and in this article we are going to simplify them and discuss what the differences are, problems and solutions to the GI and GL, and what you should be paying attention to.

Whitney and Colleagues from the text book “Understanding Nutrition” state that the glycemic index (GI) is a concept that ranks foods on how quickly they cause a rise in blood sugar and also caused by Insulin.

The rate of the rise in blood sugar is indexed against a reference food, which is usually white bread.  So, if white bread is rated as having a GI of 100, a food with a GI of 60 will cause 60% of the increase in blood sugar that white bread would cause.

The glycemic index compares the potential of foods containing the same amount of carbohydrate to raise blood glucose. However, the amount of carbohydrate consumed also affects blood glucose levels and insulin responses.

In 2002, Liu and Colleagues state that the glycemic load of a food is calculated by multiplying the glycemic index by the amount of carbohydrate in grams provided by a food and dividing the total by 100.

Dietary glycemic load is the sum of the glycemic loads for all foods consumed in the diet. The concept of glycemic load was developed by scientists to simultaneously describe the quality (glycemic index) and quantity of carbohydrate in a meal or diet.

We will discuss all of this in depth and leave you with some practical solutions.


What are GR, GI, and GL All About?

GR stands for “Glycemic Response”

GI stands for “Glycemic Index”

GL stands for “Glycemic Load.”

Let’s see what these big three are all about:


Glycemic Response

Whitney and Colleagues described the glycemic response as to how quickly glucose (predominantly from carbohydrates) is absorbed after a person eats, how high blood glucose rises, and how quickly it returns to normal.

An example of a low glycemic response would be… slow absorption rate with foods, a modest rise in blood glucose, and smooth return back to normal.

An example of a high glycemic response would be… fast absorption rate with foods, a high rise in blood glucose, and an overreaction that plunges glucose below normal.


Glycemic Index

Whitney and Colleagues described the glycemic index to different foods eliciting different glycemic responses. The glycemic index classifies foods from low, moderate, and to high… meaning specific foods are labeled this way for classifying foods accordingly to their potential for raising blood sugar.

Examples of low glycemic index foods are:


As you can see these low GI foods are considered predominantly whole and minimally refined food sources, which is what you want the majority of your nutrition plan to consist of.

Examples of moderate glycemic index foods are:


As you can see these moderate GI foods are also whole and minimally refined food sources and very fiber dense, which again, is what you want the majority of your nutrition plan to consist of.

Examples of high glycemic index foods are:


As you can see with the high GI foods you still have some decent nutrient dense food sources on there, along with more refined carbohydrate sources, and some empty calorie foods like sports drinks, and candies.


Glycemic Load

Whitney and Colleagues described the Glycemic Load as to the impact of carbohydrate consumption using the glycemic index while taking into account the amount of carbohydrate that is being consumed. In other words, GL is a GI weighted measure of carbohydrate intake.

Glycemic load of a serving of food can be calculated as its carbohydrate content measured in grams (g), multiplied by the food’s GI, and divided by 100.

Here’s an example of how to determine a foods GL:

An apple has a GI of 38. A 150g serving of apple has 19g of carbohydrates. Making the calculation 19×38/100= 7.22, so the Glycemic Load is 7.2.

The 2013 ISSN Text Book by Smith-Ryan and Antonio, states that for one serving of a food, a GL greater than 20 is considered high, a GL of 11-19 is considered medium, and a GL of 10 or less is considered low. Foods that have a low GL in a typical serving size almost always have a low GI.

Now that you have an idea of what the big three consist of, we can dig into some problems pertaining to the three.


5 Problems with the Glycemic Index

Problem #1: Researchers have said the glycemic response is something everyone should take a close look at and apply to their nutrition plan.

The Solution: in 2008 The U.S Department of Health and Human Services showed the glycemic response may be particularly important to people with diabetes, which may benefit from limiting foods that produce to great of a rise on or too sudden of a fall in blood glucose.


Problem #2: Some researchers, such as Dr. Jenni Brand Miller who runs the glycemic index website, have argued that you should eat primarily low GI foods for optimal blood sugar and weight control.

The Solution: James Krieger stated “One problem with the GI is that foods are usually tested by themselves.  However, combining foods of different GI’s, and/or adding in protein and fat, can change the GI.  This is a problem when trying to use the GI system, because most people consume mixed meals. Thus, it is questionable whether you can estimate the GI of a meal or entire diet.” 


Problem #3: Some researchers have developed a formula to estimate the glycemic index of an entire meal; however, research results have not been consistent when looking at the reliability of this formula.  Some research has shown the formula to not work very well, while other research has shown good agreement between the actual glycemic index and formula-predicted glycemic index of a meal.

The Solution: A 2011 study out of the Journal of The American Journal of Clinical Nutrition showed that the formula used to calculate the GI of mixed meals overestimated the meal GI by up to 22 – 50%.  This is a large overestimation, and further questions whether GI is a useful tool for most people


Problem #4: Researchers and GI advocates claim that people should make their food choices based off of the GI system.

The Solution: You really shouldn’t rely on GI to dictate your food choices.  It is simply too unreliable.  It is better to pay attention to fiber content and overall food quality when determining your carbohydrate choices.


Problem #5: One popular belief regarding GI is that high GI foods are not as satiating as low GI foods.  The thought is, if a food breaks down more quickly into glucose in the blood, it will cause a rapid rise in blood sugar, followed by a rapid fall.  This rapid fall in blood sugar would then stimulate hunger.  This would theoretically lead to overeating.  

The Solution: In 2014, Wu and Colleagues showed the opposite of what many believe regarding GI.  Many people think that high GI foods are less satiating, which would cause you to eat more.  However, the high GI meals were actually more satiating in this study.  This questions the idea that a rapid rise and fall in blood sugar due to a high GI meal would create hunger and causes someone to overeat.

A great example is a white potato, it has a high GI index, but it’s considered a nutrient dense food source that contains a lot of vitamins and minerals. In fact, a 1995 paper from the European Journal of Clinical Nutrition showed that potatoes are the number one satiating food some can eat during a weight loss phase.


What Should we Pay Attention to

In the very in depth article The Utility of the Glycemic Index: The Final Nail?” By James Krieger, he states the following, “One problem with the GI is that foods are usually tested by themselves. However, combining foods of different GI’s, and/or adding in protein and fat, can change the GI. This is a problem when trying to use the GI, because most people consume mixed meals. Thus, it is questionable whether you can estimate the GI of a meal or entire diet.”

Krieger also states, “The bottom line is that GI is very limited in its usefulness. It can have some utility when you are looking to get a rapid rise in blood sugar after a workout to enhance glycogen replenishment in your muscles, or if you have diabetes and are consuming an individual food and need to watch your blood sugar. But when it comes to mixed meals or an overall diet, the glycemic index should go the way of the dodo.”

We are in full agreement with what Krieger is saying here in his above statements. 90-100% of the time we as athletes and especially the Mountain Dog Community will always consume a balance of protein, carbs, and fats with each meal. It is very rare that we will just consume a carbohydrate source and measure its GI index. Therefore, the GI of a food source should not be relevant within your daily nutritional regimen. What should matter is you being consistent within your daily macros, training hard, and having a balance of enjoyable nutrient dense foods along being consistent over the course of time.


Practical Solutions

We are huge advocates on providing our audience with practical solutions and giving detailed direction.

  • Increasing the consumption of daily fiber through whole grains, nuts, legumes, fruit, and non-starchy vegetables
  • Include whole and minimally refined carbohydrate sources
  • Decreasing the consumption of sugary foods like cookies, cakes, candy, and soft-drinks
  • Partition more of your daily carb allotment pre and post workout. Our bodies regulate glucose better during training and insulin sensitivity is higher
  • Try having 50% of your preworkout carb source come from faster digesting carbs (Higher GI) so your body uses glucose rather than stored glycogen and you get an instant burst of energy
  • Then for your post workout you could have lower GI based foods that will digest slower and keep you fuller
  • Most of all focus on: adherence and consistency, your daily calories, and macronutrient ratios with a good variety of nutrient dense foods


Give this a try and let us know how you like it.