Glycemic Index Vs Glycemic Load
by Benjamin Bunting BA(Hons) PGCert
Written by Ben Bunting: BA, PGCert. (Sport & Exercise Nutrition) // British Army Physical Training Instructor // S&C Coach.
When it comes to managing blood sugar levels, understanding the impact of carbohydrates is crucial.
Two terms that often come up in this context are glycemic index and glycemic load.
If you have diabetes, chances are you're familiar with glycemic index (GI) and glycemic load (GL). These measures of blood sugar levels' response to carbohydrates help explain how quickly certain foods raise them.
However, Glycemic Index (GI) only takes into account the nature of food rather than portion sizes when determining its GI value; meaning carrots and strawberries tend to have lower GI than watermelons or doughnuts.
In this guide, we will explore the difference between these two concepts and how they can help you make informed choices about your diet.
What is the glycemic index?
Glycemic index (GI) is a measure of how quickly a carbohydrate-containing food raises blood sugar levels.
It ranks foods on a scale from 0 to 100, with higher values indicating a faster and greater increase in blood sugar.
Foods with a high GI are quickly digested and absorbed, causing a rapid spike in blood sugar levels.
On the other hand, foods with a low GI are digested and absorbed more slowly, resulting in a slower and more gradual increase in blood sugar.
Understanding the GI of foods can help individuals with diabetes or those looking to manage their blood sugar levels make better food choices.
Although the Glycemic Index provides some insight, it doesn't fully illustrate how food impacts blood sugar.
That is why nutritionists developed another tool known as the Glycemic Load or "GL".
This metric takes into account not only how fast carbohydrates convert to glucose but also the total carb content per typical serving - foods with lower GLs don't cause sudden spikes in blood sugar and insulin levels that could eventually lead to diabetes.
Glycemic index (GI) measures how quickly carbohydrates convert to energy.
However, glycemic load (GL) goes beyond this classification by taking further into account carbohydrate concentration levels within typical portions.
A food's GL can be determined by multiplying its GI index number with total amount of carbohydrates found within an average serving and then dividing by 100.
A medium doughnut contains 23 g of carbs so its GL would be 10.
A watermelons with similar GI may have lower GL ratings due to having less carbohydrate contained within each serving size of their total carbohydrate total in one serving size than in one case of doughnut.
Food's glycemic index rating may also differ based on its composition; for example, peanut butter sandwich has a higher GI score than apples due to the additional fat and protein that slows absorption of carbs from it.
Foods with a high glycemic index tend to digest rapidly and cause sharp rises in blood sugar, or glucose.
This is because they contain simple carbohydrates (one or two sugars linked together which break down and release their sugar rapidly into the bloodstream) instead of complex carbohydrate foods such as beans, lentils and peas which digest more slowly.
As when considering the glycemic index, it's essential to keep in mind that its measure only refers to eating one food alone without any others present in one meal.
Therefore, any diet based solely on this index would leave out many essential nutrients from fruits, vegetables, legumes nuts and whole grains, including those low on the glycemic index which tend to digest slowly due to being rich in dietary fiber fat and protein; helping delay release of carbohydrates into bloodstream.
What is the glycemic load?
Glycemic load (GL) takes into account both the quality and quantity of carbohydrates in a serving of food.
It is calculated by multiplying the glycemic index of a food by the amount of carbohydrates in a serving and dividing by 100.
This gives a more accurate measure of how a food will affect blood sugar levels. Foods with a high glycemic load will cause a larger and more rapid increase in blood sugar levels, while foods with a low glycemic load will have a smaller and slower impact.
Carbs provide our bodies with energy, yet there are numerous types of carbohydrates found in foods.
One way of ranking carbohydrates-containing foods according to how quickly they raise blood sugar levels is the Glycemic Index.
Foods containing processed and refined sugar have a higher glycemic index index rating, while whole foods like unrefined grains, non-starchy vegetables and fruits tend to have lower scores.
Glycemic load provides another measure used to help people make healthier food choices.
Glycemic load (GL), calculated by multiplying a food's glycemic index (GI) with its actual carb content per serving and then dividing by 100, measures the level of carbohydrates found within one food serving.
Higher values indicate more carbohydrates present. A food with a GL of 20 or higher should be considered high; 11-19 are moderate levels while 10 or lower fall under low category.
Glycemic index and load should be utilized alongside other tools, such as food labels, to assist individuals in making healthier eating decisions.
A balanced dietary pattern includes foods from all five food groups containing vitamins, minerals, protein and fiber as well as low-fat dairy, lean meats, fish and whole grains in a healthy dietary pattern.
Glycemic index can be useful when selecting a diet rich in nutrients but low in fat.
However, sole reliance should not be put on it due to it not taking into account other pertinent information like portion sizes.
Diets that are low in glycemic load can help protect against complications associated with diabetes.
Studies have demonstrated the power of such diets in controlling glucose levels, improving cholesterol and triglyceride levels and supporting weight loss.
A diet with such properties should be combined with other strategies for managing blood sugar, such as carb counting or maintaining a healthy weight to achieve maximum benefit.
By considering both the glycemic index and glycemic load of foods, individuals can make more informed choices to manage their blood sugar levels effectively.
How is the glycemic index determined?
Foods that digest quickly and release glucose quickly have a higher glycemic index rating; however, how you eat your foods also impacts their GI rating.
For instance if you eat an apple either alone on its own or together with peanut butter it could have different blood sugar effects due to protein and fat present in nuts or peanut butter slowing the rate at which your body digests and absorbs its carbs from apple.
This means a glycemic index chart which only looks at carbohydrate content doesn't give an accurate depiction of how certain foods will affect blood sugar.
To account for this, the Glycemic Load (GL) was developed as a measure that takes both GI and portion size into account.
GL can be calculated by multiplying a food's glycemic index with its carb content per serving and then dividing by 100.
This provides a more accurate depiction of how certain foods will impact blood sugar, as it accounts for how many grams you're consuming at any given time.
Low GL foods have scores less than 10, moderate scores between 11-19 and high GL foods have scores over 20.
While the Glycemic Index can be useful, it's important to keep in mind that not all carbohydrates are equal and it may be wiser to opt for a diet rich in whole food nutrition rather than focussing on specific "low GI" food items.
Furthermore, since some lean proteins and healthy fats do not contain carbs they won't appear on any glycemic index list.
If you decide to utilize the Glycemic Index as a way of selecting meals.
The Academy of Nutrition and Dietetics suggests selecting foods with a Glycemic Index rating of 55 or lower as they will help prevent sustained spikes in blood sugar, which have been linked with an increased risk for diabetes and other health conditions.
How is the glycemic load determined?
The Glycemic Index ranks food according to how quickly their blood sugar rises after they're eaten and assigns them a score from 0 to 100.
Foods with lower GI scores are considered slow-acting and won't keep blood sugar levels elevated for extended periods.
Those with higher scores, on the other hand, tend to quickly digest and be absorbed into bloodstream causing rapid increases in blood sugar.
Such foods often include processed carbohydrates and sugars.
Glycemic loads go beyond the basic glycemic index by taking into account the total carbs present in an average serving, providing more accurate predictions about how a food will impact blood sugar.
To calculate it, multiply its glycemic index with its grams of carbohydrates per average serving and divide that resultant figure by 100 to get its glycemic load score.
Foods with low glycemic loads tend to be healthy while those with higher loads should only be eaten occasionally, as these cause large and sustained spikes in blood sugar that could eventually lead to insulin resistance and, eventually, type 2 diabetes.
Glycemic index can be misleading when used to judge food's healthfulness, since high-carbohydrate foods often also contain fiber which slows digestion.
Furthermore, this measure does not take into account non-carbohydrate foods like meat and butter which don't fall under its scope.
Though its limitations, the Glycemic Index remains useful in distinguishing slow-acting "good carbs" from fast-acting "bad carbs" as a guide for understanding which carbohydrates impact blood sugar and insulin levels more significantly, as well as managing your overall diet and health goals more easily.
When combined with other tools like carb-counting, using the GI can help fine-tune eating habits for maximum blood sugar management in a healthy range.
How are Glycemic Index and Glycemic Load calculated?
The glycemic index (GI) of a food is determined by measuring the blood sugar response to consuming a fixed amount of carbohydrates from that food.
This response is compared to the blood sugar response from consuming the same amount of carbohydrates from a reference food, usually glucose or white bread.
The GI is then expressed as a percentage, with glucose or white bread having a GI of 100.
Foods with a high GI (above 70) are considered to cause a rapid and large increase in blood sugar levels, while foods with a low GI (below 55) cause a slower and smaller increase.
- To calculate the glycemic load (GL) of a food, the GI is multiplied by the amount of carbohydrates in a serving and divided by 100.
- For example, if a food has a GI of 60 and contains 30 grams of carbohydrates per serving, the GL would be (60 x 30) / 100 = 18.
This gives a more comprehensive measure of how a food will affect blood sugar levels, taking into account both the quality and quantity of carbohydrates.
It's important to note that the GI and GL are not absolute values, as they can vary depending on factors such as cooking methods, ripeness of fruits, and food combinations.
However, they provide a useful tool for individuals looking to manage their blood sugar levels and make informed choices about their carbohydrate intake.
How do they affect blood sugar levels?
Both the glycemic index (GI) and glycemic load (GL) can affect blood sugar levels, but in different ways.
The GI measures how quickly and how much a food raises blood sugar levels, while the GL takes into account both the quality and quantity of carbohydrates in a serving.
Foods with a high GI (above 70) cause a rapid and large increase in blood sugar levels.
This can lead to a spike in energy followed by a crash, as well as potential long-term health issues such as insulin resistance and diabetes.
On the other hand, foods with a low GI (below 55) cause a slower and smaller increase in blood sugar levels, providing more sustained energy and better blood sugar control.
The GL provides a more comprehensive measure of how a food will affect blood sugar levels.
It takes into account both the GI and the amount of carbohydrates in a serving. This means that a food with a high GI can still have a low GL if the serving size is small, and vice versa.
By considering both the quality and quantity of carbohydrates, the GL gives a more accurate picture of how a food will impact blood sugar levels.
Understanding the difference between the GI and GL can help individuals make informed choices about their carbohydrate intake.
By choosing foods with a lower GI and GL, individuals can better manage their blood sugar levels and support overall health.
Tips for managing your carbohydrate intake based on Glycemic Index and Glycemic Load
Here are some tips for managing your carbohydrate intake based on the Glycemic Index (GI) and Glycemic Load (GL):
1. Choose low GI foods
Opt for foods with a low GI, as they cause a slower and smaller increase in blood sugar levels. These include whole grains, legumes, non-starchy vegetables, and most fruits.
2. Combine high GI foods with low GI foods
If you want to consume a high GI food, such as white bread or white rice, pair it with a low GI food, like vegetables or protein. This can help balance out the impact on blood sugar levels.
3. Pay attention to portion sizes
The GL takes into account both the GI and the amount of carbohydrates in a serving. Be mindful of portion sizes, as even a high GI food can have a low GL if the serving size is small.
4. Include fiber-rich foods
Foods high in fiber, such as whole grains, fruits, and vegetables, can help slow down the absorption of carbohydrates and prevent spikes in blood sugar levels.
5. Avoid processed and sugary foods
Processed foods, sugary snacks, and beverages tend to have a high GI and GL. Limit your intake of these foods to better manage your blood sugar levels.
6. Experiment with different cooking methods
The way you cook your food can affect its GI. For example, steaming or boiling potatoes results in a lower GI compared to frying them.
7. Monitor your blood sugar levels
If you have diabetes or are at risk of developing it, regularly monitor your blood sugar levels to understand how different foods and portion sizes affect you personally.
8. Consult a healthcare professional
If you have specific dietary needs or health concerns, it's always a good idea to consult a healthcare professional or registered dietitian for personalized advice.
By incorporating these tips into your diet, you can make informed choices about your carbohydrate intake and better manage your blood sugar levels.
Remember, everyone's body is different, so it's important to find an approach that works best for you.
Have you ever eaten something and then experienced an energy dip shortly afterwards?
This may have been due to hypoglycemic event - otherwise known as blood sugar dip.
While usually associated with people living with diabetes, hypoglycemic events can affect anyone whose blood sugar fluctuates frequently.
According to John Hopkins Medicine it can contribute to fatigue, poor performance and irritability.
Though fluctuations in blood sugar don't pose immediate danger for all, they do increase the risk of diabetes and certain cancers, making it imperative that it stays stable - and there's an easy way to do it!
Glycemic Index and Load Two essential tools for controlling your blood sugar and insulin levels are the Glycemic Index and Load.
Glycemic Index ranks carb-rich foods based on how quickly they raise your blood sugar; Glycemic Load takes into account how many carbohydrates (in grams).
Glycemic index measures how 50 grams of carb-rich food affect your blood sugar level - this number ranges between one and 100; pure glucose receiving the maximum score possible.
Make note that the GI of food can fluctuate greatly based on its ripeness, cooking method, and processing techniques.
You can easily check its GI by searching an online database; note however that certain foods such as meats and oils do not contain carbohydrates and therefore do not qualify for an official GI score.