The Glycemic Index (GI) has been used for decades to help people understand how their food intake can affect their glucose levels. As the science of nutrition and dietary management continues to evolve, so too does the need to evaluate whether or not the GI remains a reliable tool.
This article will dive into the accuracy of using this index and whether any modifications are necessary for it to remain effective.
What is Glycemic Index (GI)?
Dr. David J. Jenkins and his colleagues at the University of Toronto made history when they developed the concept of glycemic index in 1980-1981. Their goal was to find a diet that could be highly advantageous for people diagnosed with diabetes.
The glycemic index measures how quickly a food is digested and absorbed into the bloodstream as glucose, causing an increase in blood sugar levels. The glycemic index is measured on a scale of 0-100, with higher values indicating a faster rise in blood sugar levels. Foods with a low glycemic index (GI) release glucose slowly into the bloodstream, while high GI foods cause a rapid spike in blood sugar.
The three glycemic index categories are low, medium, and high.
- Low GI (55 or less): Foods with a GI of 55 or below are considered low.
- Medium GI (56-69): Medium GI foods have a value between 56-69.
- High GI (70 to 100): High GI foods have a value between 70-100.
Here’s the difference between these three categories:
Foods with low GI values are digested and absorbed slowly, causing gradual increases in blood sugar levels. In contrast, high GI foods are rapidly digested and absorbed into the bloodstream, causing sharp spikes in blood sugar levels. And, foods with medium GI values rank between those with high and low GI values, meaning they are absorbed by the body at a moderate pace, releasing glucose into the bloodstream more slowly than high-GI foods.
There are several reasons why you might opt for low-glycemic index (GI) foods:
- Weight management: If you are looking to shed some pounds or maintain a healthy weight, a low-GI diet can be a beneficial choice. Foods with a low GI value are known to help regulate blood sugar levels, keeping you fuller for longer, and reducing the risk of overeating.
- Healthy meal planning: Following a low-GI diet can assist you in planning and consuming well-balanced meals. By incorporating low-GI foods into your diet, you can ensure a steady release of energy throughout the day, helping you feel more satisfied and focused.
- Blood sugar management for diabetes: If you have diabetes, a low-GI diet can be a valuable tool in managing blood sugar levels. Low-GI foods are absorbed more slowly, causing a gradual rise in blood sugar, which can help prevent sudden spikes or drops in glucose levels.
- Heart health: Incorporating a low-GI diet into your lifestyle may also reduce the risk of heart diseases and other cardiovascular conditions. Low-GI foods are associated with improved insulin sensitivity and better blood lipid profiles, which can contribute to overall heart health.
After taking the time to read this, you may be inclined to think that the glycemic index is a beneficial concept. However, it is important to pause before making any decisions, as there are many underlying issues with the glycemic index that renders it obsolete.
The Glycemic Index (GI) is a Measure of How Much a Certain Food Raises Blood Glucose Levels:
The glycemic index (GI) is a measure of how quickly a particular food raises blood glucose levels compared to a reference food (usually glucose) which is assigned a GI value of 100.
Note: GI only reflects how quickly a certain food raises blood glucose levels. For example: Whether you eat one bowl of watermelon or consume a whole watermelon, the GI of the watermelon will remain the same, which is 72.
However, it’s worth noting that the glycemic index is based on consuming a fixed amount of available carbohydrates in a food, typically 50 grams of carbohydrates. Since watermelon is relatively low in carbohydrates (about 6 grams of carbohydrates per 100 grams), the actual impact on blood glucose levels from consuming watermelon may be different in real-world scenarios, as most people do not consume 50 grams of carbohydrates from watermelon in a typical serving.
This is where the concept of glycemic load (GL) can be helpful, as it takes into account both the GI and the quantity of carbohydrates consumed.
What is Glycemic Load (GL)?
Glycemic load (GL) is a measure that takes into account both the glycemic index (GI) and the quantity of carbohydrates in a specific serving size of food. It provides a more comprehensive picture of how a food may affect blood glucose levels compared to the glycemic index alone.
Glycemic load is calculated using the following formula: GL = (GI × grams of available carbohydrates in a serving) / 100
The grams of available carbohydrates in a serving refer to the total amount of carbohydrates in a food minus the amount of dietary fiber. This is because dietary fiber is not digested and does not contribute to the rise in blood glucose levels.
By multiplying the GI by the grams of available carbohydrates in a serving and dividing by 100, the glycemic load provides an estimate of the overall impact of a specific serving size of a food on blood glucose levels.
The three glycemic load categories are low, medium, and high.
- Low GL (10 or less): Foods with a GL of 10 or below are considered low.
- Medium GL (11-19): Medium GL foods have a value between 11-19.
- High GL (20 or above): High GL foods have a value of 20 or above.
More Than Glycemic Index (GI), It Is Glycemic Load (GL) That Matters:
While the glycemic index (GI) is a useful measure of how quickly a particular food raises blood glucose levels, the glycemic load (GL) provides a more comprehensive picture of the overall impact of a specific serving size of a food on blood glucose levels.
The glycemic load takes into account both the GI and the quantity of carbohydrates in a serving of a food, which provides a more accurate assessment of how a particular food may affect blood sugar levels. A high GI food may not necessarily result in a significant increase in blood glucose levels if the serving size is small, and vice versa. The glycemic load considers the actual amount of carbohydrates in a serving, which allows for a more realistic estimation of the potential impact on blood glucose levels.
Foods with a high GI but a low glycemic load may be less likely to cause a rapid and large increase in blood sugar levels, as the overall quantity of carbohydrates consumed is low. On the other hand, foods with a low GI but a high glycemic load may still have a significant impact on blood glucose levels if consumed in large quantities.
For example: Watermelon has a high glycemic index (GI) of 72, which indicates that it may cause a relatively rapid and large increase in blood glucose levels. However, watermelon also contains a high water content and relatively low carbohydrate content (about 6 grams of carbohydrates per 100 grams). This means that the glycemic load (GL) of watermelon is relatively low, estimated to be around 4, as calculated using the formula: GL = (GI × grams of available carbohydrates in a serving) / 100.
Side By Side Comparision:
Glycemic Index (GI):
Sugar has GI ~ 65
Potato has GI ~ 80
So according to the glycemic index, sugar will come under the medium and potato high glycemic index category.
Glycemic Load (GL):
Let’s say we are taking 100 gms of each sugar and potato. 100 gm sugar has 100 gm of carbs and 100 gm of potato has ~ 17 gm of carbs.
So, Sugar GL ~ (65 × 100) /100 = 65 (High GL)
And, Potato GL ~ (80 × 17) /100 = 13.6 (Medium GL)
Considering the glycemic index, if you had to select one of the two food items, which would you choose? It is likely that sugar would be selected due to its relatively low GI.
Now, with regard to GL values, could you tell me which of the two options you would prefer in this case? It’s certainly potato from what I understand because it also has relatively low GL.
GL is a beneficial factor to consider when selecting foods, as it helps to offset the limitations of GI by taking into account the amount of carbohydrates ingested.
Note: I am sure that no one would want to consume 100g of sugar, as that is far too excessive an amount. Similarly, someone choosing potatoes will likely want more than just 100g worth. My aim in making this comparison is solely to demonstrate the superiority of using Glycemic Load (GL) over Glycemic Index (GI). Nothing else.
Should We Label Foods As Good Or Bad On the Basis of the GI or GL?
Labeling foods as “good” or “bad” solely based on their GI or GL may not be appropriate as it can be overly simplistic and may not necessarily reflect the overall healthiness of a food. Here are some points to consider:
- Context matters: GI and GL are influenced by various factors, such as food processing, cooking methods, and food combinations. The presence of fat, protein, and fiber in a meal can affect the glycemic response. Thus, a food with a high GI or GL when consumed alone may have a different effect when consumed as part of a balanced meal.
- Nutrient density: Foods are not just sources of carbohydrates, but also provide other important nutrients like protein, healthy fats, vitamins, and minerals. Labeling foods as “bad” based on GI or GL may overlook their overall nutrient content and potential health benefits.
- Individual differences: People’s glycemic response to foods can vary based on their genetics, gut microbiota, activity level, and other factors. What may cause a significant blood sugar spike in one person may not have the same effect on another. Generalizing foods as “good” or “bad” based on GI or GL may not account for these individual differences.
- Balanced eating patterns: Healthful eating is about overall dietary patterns, not just focusing on individual nutrients or measures. A balanced and varied diet that includes a wide range of foods can provide the necessary nutrients for optimal health, rather than just focusing on specific foods labeled as “good” or “bad” based on GI or GL.
Instead of labeling foods as “good” or “bad” based solely on GI or GL, it’s important to consider the overall nutrient profile of a food, individual differences, and the context of how foods are consumed in a balanced diet.
Smart Eating: Food Selection Pyramid to Eating Well:
If you are living with diabetes or not, it is beneficial to be mindful of each important food group and include these in your diet for optimal health. Here is an informative version of the food pyramid that can guide you in making smart choices when crafting your meals.
So let’s understand all the components of the food selection pyramid.
Step 1: Complete Your Protein Needs:
When it comes to selecting food, protein should be at the top of your list. Protein is an essential component of a healthy diet and is critical for the growth and repair of tissues in your body. It also plays a crucial role in maintaining muscle mass, supporting immune function, and regulating hormone levels.
When selecting foods that are high in protein. Some great options include lean meats like chicken or turkey, fish such as salmon or tuna, and eggs.
To begin, you should have a daily protein intake (in grams) of 1.6 times your body weight and then incrementally increase it until reaching a daily protein requirement (in grams) corresponding to 2.2 times your body weight.
As an example, if your body weight is currently 60kg then you can begin by including 96g of protein in your diet every day (which would be 60 x 1.6).
Step 2: Complete Your Fat Needs + Include Green Veggies:
Now that you have taken care of your daily protein requirements, I suggest adding some foods rich in fats and green vegetables to your diet.
Opt for healthy fats, such as monounsaturated fats and polyunsaturated fats, which can provide numerous health benefits. Foods rich in healthy fats include avocados, nuts, and seeds (such as almonds, walnuts, chia seeds, and flaxseeds), fatty fish (such as salmon, mackerel, and trout), olive oil, and coconut oil. These fats can help promote heart health, support brain function, and provide energy.
Green vegetables are packed with essential vitamins, minerals, fiber, and phytonutrients that can support overall health. Examples of nutrient-rich green vegetables include spinach, kale, broccoli, Brussels sprouts, collard greens, asparagus, and green peas.
For optimal health and energy levels, it is recommended that you maintain a minimum of 0.6 grams of fat per kilogram of your body weight.
As an example, if your body weight is currently 60kg then you should include at least 36g of fat in your diet every day (which would be 60 x 0.6).
Step 3: Complete Your Carbs Needs (Use Glycemic Load):
In the third step, you can consider utilizing glycemic load when choosing carbohydrate food sources. When managing your plate size, select food items with a low to medium glycemic load.
For example, if you like to eat rice, then you can eat lentils with it. Suppose you eat 70 gm white rice and eat 50 gm chickpeas with it. So calculation will be like this:
Since 70 gm rice will have around 19.6 gm carbs and since the GI of white rice is 72 then by calculating, GL = (72*19.6)/100 =14.112 (medium GL).
Since 50 gm of chickpeas will have around 30.5 gm carbs and since the GI of chickpeas is 28 then by calculating, GL = (28*30.5)/100 = 8.54 (low GL).
Taking into account that you are consuming rice and chickpeas together, the glycemic load will decrease further and be situated in a range between low to medium.
Also, you can include some low-GL fruits like watermelons, and oranges in your diet.
While GI and GL can provide guidance, it’s important to use common sense and consider the overall nutrient profile of foods, rather than relying solely on GI or GL values.
It is important to note that carbohydrates alone are not unhealthy. Instead, it can be detrimental to have an intake of either too much or insufficient amounts of carbohydrates in one’s diet.
It is essential to remember that quantity is an important factor to consider when managing one’s blood sugar levels. Even if lower glycemic index values are found in certain carbohydrate-based foods, having larger portions will still lead to relatively higher blood sugar readings. Thus it is wise to practice moderation and combine proteins, fats, and fiber into meals for the purpose of reducing their glycemic reaction.
If you still would like to make a decision between glycemic index and glycemic load, then the glycemic load is generally far more trustworthy as it takes into account not just the quality and volume of carbohydrates in the diet but also their interactions in your body.
And, glycemic index? Yeah, why do we even need that? C’mon now, it’s only necessary ’cause it helps us figure out the Glycemic Load – nothing else!
Published on April 19, 2023 and Last Updated on April 21, 2023 by: Priyank Pandey