Why glycaemic load matters more than glycaemic index in blood sugar management

Doctors explain why glycaemic load offers a truer measure of how foods affect blood sugar. The distinction can help people with diabetes plan portions and meals more effectively.

In Short

• GI measures how quickly carbohydrates raise blood sugar, not serving size
• GL combines carbohydrate quantity and speed to estimate actual meal impact
• Doctors advise smaller portions with protein, fibre and healthy fats

In many Indian homes, managing diabetes is part of everyday life. It even shapes dinner-table conversations, and almost every meal seems to bring up the same dilemma: is the juicy mango the enemy, or is the generous serving of rice doing more harm?

For years, people have leaned on the glycaemic index (GI) as their go-to guide, only to find themselves confused because healthy choices are not necessarily helping bring down the sugar spike. But glycaemic load (GL) is a better tool to measure a food's impact on blood glucose and insulin response than glycaemic index alone.

According to Dr. V. Mohan, a renowned Diabetologist, “GL reflects the real-life blood sugar impact of food portions, making it much more practical for meal planning.” But how? Let’s understand what it is and how it is measured.

WHAT IS GLYCAEMIC INDEX & GLYCAEMIC LOAD

The glycaemic index basically tells you how fast a carbohydrate food raises your blood sugar, whereas glycaemic load tells you how much quantity of that food can actually raise the blood sugar.

While the glycaemic index indicates how quickly a food can raise blood sugar compared to pure glucose, using a scale from 0 to 100, it doesn't consider how much of that food you're actually eating. That's where glycaemic load comes in. It looks at both how quickly the food raises blood sugar and how many carbohydrates are in a typical serving, giving you a more realistic picture of its effect on your blood sugar.

Dr. Bhavya Arora, a clinical nutritionist and certified diabetes educator from C-Doc Hospital explained, “glycaemic load can be calculated by glycaemic index into the available carbohydrates in the food serving which you can divide by 100. So low glycaemic load foods are less than 10, medium glycaemic load food is 11 to 19 and high glycaemic load is more than 20.” So, it’s GI carbohydrate in one serving 100.

The ranking for glycaemic load is as follows:

Low = 10 or less

Medium = 11-19

High = 20 or more

Dr. Mohan cited an example. He said that “watermelon causes blood sugar to rise quickly because its sugars are absorbed rapidly. However, since watermelon contains about 90% water, a typical slice has relatively little carbohydrate.”

“Therefore, its overall blood sugar effect is small when eaten in moderation,” he added.

So, despite carrying a high GI of roughly 72–80, watermelon has low carbohydrate density per serving, meaning its GL sits at a modest 5, making it low on glycaemic load.

Now white rice tells the opposite story. It’s a moderate GI paired with generous portion sizes. Why? Because when eaten during a meal, an adult may end up consuming at least half a cup of rice or sometimes more.

“White rice has a glycaemic index of about 70 to 75, and it also varies by the type of cooking. But 100 grams of cooked rice contains about 28 grams of carbohydrates. So when you calculate the glycaemic load of white rice (75 into 28 divided by 100), it comes out to be 21, which is a high glycaemic load," explained Dr. Arora.

This pushes its GL considerably high. Now this translates into a slow, steady rise in sugar and is considered a more damaging blood sugar climb.

FOR DIABETES, GLYCAEMIC LOAD MATTERS

Glycaemic load provides a more realistic picture of a food's true impact on your blood glucose levels. Some foods have a high glycaemic index but very few carbohydrates per serving.

According to Dr. V. Mohan, watermelon and pumpkin have high GI but low GL per serving. Similarly, cooked carrots have moderate to high GI levels but low GL per serving. He said that “it happens because these foods contain lots of water and relatively little carbohydrate per serving.”

We asked him if there were any food items that may have a high glycaemic load but are low on the glycaemic index. He explained that "this is less common but possible. Foods with a low GI can still have a high GL if eaten in large amounts because they contain a lot of carbohydrate.”

For example, brown rice has a medium glycaemic index but a high glycaemic load. Similarly, oats are low on the GI scale, yet a large bowl can still have a moderate GL. The reason is simple: larger portions mean more carbohydrates, increasing the food's overall impact on blood sugar.

“For people with diabetes, both matter, but if choosing one, glycaemic load is generally more useful because it reflects the amount people actually eat," said Dr. Mohan.

“A good approach is to prefer foods with a low GI, watch portion sizes to keep the GL low, and pair carbohydrates with protein, healthy fats, or fibre to reduce blood sugar spikes.”

In a nutshell, GI is only a starting point, but GL is the number that actually matters at the dinner table.

To find out about food rankings and to calculate the glycaemic load, visit the Glycemic Index Research.

- Ends