The Glycemic Index vs Glycemic Load

Have you heard of the Glycemic Index (GI)?

It’s often cited in the media as an essential tool for picking carbohydrate sources and managing blood sugar.

You’ve likely seen that cereal box with LOW GI stamped on it like a badge of honour.

But what is it, and is it worth paying attention to?

While it can sound like a complicated term, simply put, the Glycemic Index is a value given to measure how fast a specific food increases blood sugar (glucose) levels.

Foods are categorised as low, medium or high glycemic, on a scale between 0-100. The lower the number, the slower your blood sugar will rise after eating it.

As a general rule, processed refined carbs and sugars tend to have a high GI, while foods higher in fibre, protein and fat have a lower GI. Foods that contain no carbohydrates are not given a GI rating. Think meats, eggs, nuts, oils, herbs, spices, etc.

But the Glycemic Index only tells us part of the story. What it can’t tell you is how high your blood glucose will actually go, only how fast it will rise.

For a more accurate blood sugar load, you need two pieces of information. How quickly glucose from a given food can enter the bloodstream (GI), and how much glucose per serving that food can deliver.

This is where the Glycemic Load measure comes in, which uses both pieces of data to provide a more accurate real-life picture of the impact on your blood sugar.

A good example of this difference in practice is watermelon. With a GI of 76, you would think this food is blood glucose enemy number one, but a serving of watermelon is so low in carbohydrates that its Glycemic Load is only 6. You would need to eat a ton of it to get a significant rise in blood sugar(1).

Other factors worth considering are food combinations. For example, white rice might be high GI when consumed alone but when combined with protein and fat like it often is, the Glycemic Load is much lower.

A good rule of thumb is to consume high GI foods with slower digesting proteins and fats to prevent giant blood sugar spikes and more consistent energy levels.

There are, however, cases when you might want blood sugar spikes for fast carbohydrate uptake, especially into the muscle tissue. Post workout, for example, you may want to restore glycogen stores as quickly as possible to recover from training. This is where high GI foods and a high glycemic load are favourable(2).

In summary, while the Glycemic Index can be a useful tool, using Glycemic Load is a more practical method of managing blood sugar. This is important for long-term blood glucose management, energy levels throughout the day and body fat storage optimisation.

The macro factors like overall activity levels, and caloric and macronutrient intake are still king for aesthetic development, so ensure these are prioritised when diving deeper into more micro considerations like blood sugar management.

References

Facts, G., 2022. WATERMELON – Glycemic Index. [online] Glycemicindex.com. Available at: https://glycemicindex.com/2021/11/watermelon [Accessed 31 July 2022].
JL, I., 2022. Regulation of muscle glycogen repletion, muscle protein synthesis and repair following exercise. [online] PubMed. Available at: https://pubmed.ncbi.nlm.nih.gov/24482590 [Accessed 31 July 2022]