Why Glycaemic Load Matters More Than Glycaemic Index

The simple concept that could change the way you think about sugar control.

If you’ve ever searched for the “best foods for diabetes,” you’ve probably come across the term Glycaemic Index (GI).

Many people assume that a low GI automatically means a food is good for blood sugar—and that a high GI means it should be avoided.

But the truth is a little more interesting.

When it comes to the glucose spike after a meal, Glycaemic Load (GL) is often far more useful than Glycaemic Index alone.

Think of it like driving a car 🚗

Imagine you’re driving.

The speedometer tells you how fast you’re travelling. It doesn’t tell you how far you’ll go.

That’s exactly what the Glycaemic Index (GI) does.

It measures how quickly the carbohydrate in a food can raise blood glucose.

Now imagine looking at your fuel tank. The fuel gauge tells you how much fuel you actually have.

This is similar to Glycaemic Load (GL).

It tells you how much glucose is likely to reach your bloodstream from the portion you actually eat.

GI tells you the speed.

GL tells you the amount.

And when it comes to your blood sugar after a meal, the amount often matters more than the speed.

Watermelon vs Banana: The perfect example 

Watermelon is often criticised because it has a high Glycaemic Index (around 72).

Bananas usually have a moderate GI (around 50–55).

At first glance, you might think bananas are the better option.

But here’s where Glycaemic Load changes the story.

A typical serving of watermelon is mostly water and contains relatively little carbohydrate.

That means its Glycaemic Load is only around 5, making it a low GL food.

A medium banana contains considerably more carbohydrate, giving it a Glycaemic Load of around 12–13.

So despite watermelon having a higher GI, a normal serving often places a smaller glucose load on your body than a banana.

This is why looking at GI alone can sometimes be misleading.

Why this matters for sugar control

Your body doesn’t respond to the GI number alone.

It responds to how much simple carbohydrate actually enters your bloodstream.

That’s why portion size is so important.

Two foods may raise glucose at a similar speed, but if one contains three times more carbohydrate, it will usually produce a much larger glucose challenge.

For day-to-day eating, thinking about both the quality of the carbohydrate (GI) and the quantity (GL) gives you a much better picture of how a food may affect your glucose levels.

Your body is the final judge

Everyone responds slightly differently to food.

Sleep, stress, exercise, hormones, medications and even the time of day can all influence your glucose response.

That’s why the most useful tool isn’t just a chart—it’s your own blood sugar data.

If you live with diabetes, prediabetes or insulin resistance, consider checking your response with a glucometer or continuous glucose monitor (CGM) after trying different foods.

Sometimes the results are surprising.

Food doesn’t always come with a GI and GL tag

Most foods do not come with GI and GL tag.

If this is the case, the best way to test your blood sugar response to a food is to check with a glucometer or CGM. With a glucometer, check your pre-meal sugar and your 90 minute post-meal sugar. The rise in sugar is your blood sugar spike. This is the mean way to understand which foods suit you.

Three fruits that are excellent choices for sugar control

🍐 1. Guava

• Low GI (~12–24)

• Low GL (~3–5 per serving)

• Rich in fibre and vitamin C

• One of the best fruits for maintaining steady glucose levels.

🍎 2. Apple

• Low GI (~36–40)

• Low GL (~5–6)

• The fibre (especially in the skin) helps slow glucose absorption and supports satiety.

🍐 3. Pear

• Low GI (~30–38)

• Low GL (~4–5)

• High in fibre and naturally sweet without causing large glucose excursions in most people.

Bonus: 🍉 Watermelon still deserves a place on this list. Despite its high GI, its low Glycaemic Load means that a sensible serving can fit very well into a blood sugar-friendly diet.

The takeaway

Instead of asking,

“What’s the GI?”

Try asking,

“What’s the Glycaemic Load of the portion I’m eating?”

Because when it comes to blood sugar management, GI tells you how fast… but GL tells you how much.

And in real life, how much often makes all the difference.