What Is The Glycemic Index of Whey Protein Powder?

If you’re keeping an eye on your health, you’re probably paying attention to the glycemic index of foods you eat to make sure your blood sugar levels stay balanced throughout the day.

You might be wondering about the glycemic index of supplements like protein powder, too.

So, what is the glycemic index of whey protein powder? Whey protein powder is not on the glycemic index (GI) because it contains little to no carbs.

The glycemic index is a scale that ranks how much carbohydrate-containing food raises blood sugar after consumption. Whey protein powder can actually lessen and slow the blood sugar spike of an overall meal. 

Glycemic index, glycemic load, insulin, and sugar are all hot-button topics these days. In this article, I will clear up the confusion about whey protein’s role in all of them.

Key Takeaways:

  • If whey protein powder were on the glycemic index, it would be considered a low-GI food along with lean meat, eggs, cheese, and low-sugar dairy products.
  • Consuming whey protein powder helps stimulate the release of insulin, which reduces the blood sugar impacts of eating high-carbohydrate foods and results in a lower glycemic load.
  • Nearly all commercially available whey protein powders are low in sugar and can be added to 1-2 meals per day to reduce the overall glycemic load of the meal.

Whey Protein Powder & Glycemic Index

The process of making whey protein powder from milk removes all or nearly all of the carbohydrates, which in this case are in the form of lactose.

Since whey protein powder has practically no carbs, it is not on the glycemic index (GI). If it were on the GI, it would be ranked as a low-GI food (score below 55).

Pure glucose, a simple sugar, is assigned a value of 100 to quantify how much blood glucose (blood sugars) would be expected to rise two hours after consuming it by itself.

Other carbohydrate-containing foods are then ranked relative to how much they would raise blood sugar levels compared to glucose for an equal amount of carbohydrates (usually 50g). 

Foods scoring less than 55 are low, those scoring 56-69 are moderate, and those scoring 70+ are high.

Glycemic Index Food

Whether food is cooked, how it is cooked, and how ripe it is can impact its glycemic index.

Food containing protein or fat also has a lower GI score because it takes longer to digest, which causes blood sugar to rise more slowly.

In one of the few studies specifically on whey protein powder, GI Labs, Inc tested the GI values of eight Shakeology shakes. All eight were classified as low GI, with scores averaging in the low 30s.

However, Shakeology shakes contain ingredients beyond just whey protein, so they were higher than what a pure whey isolate protein powder mixed with water would be.

How Does Whey Protein Powder Compare With Other Foods On The Glycemic Index?

Whey protein is very low compared with foods on the glycemic index. It would fit in with lean meat, eggs, cheese, and other low-sugar dairy products as low-GI food.

Since most types of protein powder have only 1-2g of carbs per scoop, it would take 25-50 scoops to get 50g of carbs to measure whey protein’s GI score.

The fact that the GI index relies on comparing an equivalent amount of carbohydrates (50g), regardless of serving size, doesn’t make it as helpful for comparing foods. 

Food could have a very high GI score based on 50g of carbs. But if the average serving size only provides 10g of carbs, it wouldn’t impact blood sugar as much.

Also, you would rarely eat a single food all by itself with nothing else included in the meal or snack.

As soon as you combine foods, especially when the foods contain protein and fat along with carbohydrates, you create a meal with a different overall GI impact than the GI score of any one food.

What About Glycemic Load?

To overcome the above challenges related to serving size and mixing foods, it’s helpful to think about glycemic load (GL) and not just glycemic index.

Glycemic load considers how much carbohydrate is in a serving of food when estimating the impact a food will have on blood sugar levels.

You can calculate the glycemic load of food by multiplying the number of carbohydrates in grams by the food’s GI and dividing that number by 100.

For example, watermelon has a GI score of 72. A 4oz serving of watermelon has 8g of carbs. Therefore, its glycemic load (GL) is 5.8 (8g x 72/100 = 5.76).

A GL score of 10 and below is low, 11-19 is medium, and 20+ is high.

Beyond serving size, the impact of mixing foods also changes how much and how quickly blood sugar rises (glycemic response). 

Because whey protein powder digests so quickly, it gets amino acids (the building blocks of protein your body releases when it breaks down the protein you eat) into your bloodstream right away. 

These amino acids let your body know to release the storage hormone insulin so that you can start absorbing these amino acids for use in the cells to repair and build new muscle tissue. 

At the same time, insulin also helps to absorb any glucose in your bloodstream that comes from carbohydrates you digested.

Storing glucose in your body’s cells as glycogen (the storage form of carbohydrates to be used as energy later) reduces your blood sugar levels.

In a study published in the Nutrition Journal, adding a whey protein supplement to a meal significantly lowered the glycemic response.

Why Does the Glycemic Index of Whey Protein Powder Matter?

Whey protein powder doesn’t have a GI score on its own. However, its ability to reduce the glycemic load of a meal that includes higher-GI foods makes it a very helpful supplement to achieve an overall lower glycemic load.

It can help you to balance your blood sugar levels over the course of a day.

Even for people with type 2 diabetes, supplementing with whey protein for meals with high-GI carbohydrates can help lower blood sugar.

Tips for Including Whey Protein Powder on a Low-Glycemic Diet

Include 1 scoop of whey protein powder at 1-2 meals or snacks per day to lower the glycemic load of the meal. Supplementing with whey protein is especially helpful for meals with high carbohydrate content.

For example, many common breakfast foods are high in quick-digesting carbohydrates (orange juice, fruit, toast, cereal, muffins, pastries, etc.). Breakfast is also a time of day when people are less likely to cook a whole food protein source. This makes breakfast a perfect time to add a protein shake with 1 scoop of protein powder.

Snack time is another time when many people also realize they are missing a protein source. It can be harder to find “grab and go” whole food sources of protein during the day, so an afternoon snack is another time I recommend adding whey protein powder. 

Pick the 1-2 meals or snacks that are highest in carbohydrates and least likely to have a whole food source of protein (like chicken breast or steak), and add 1 scoop of protein powder to those meals or snacks.

You can make a protein shake with water or another liquid or stir protein powder into your food (oatmeal, yogurt, cereal, or eggs are all good choices).

Whey Protein Powders for Low Glycemic Index

Nearly all commercially available whey protein powders are very low in carbohydrates and have little to no added sugar. This makes almost any whey protein powder a good choice for a low-GI diet.

Here are my top recommendations:

  1. Transparent Labs 100% Grass-Fed Whey Protein Isolate – Best Naturally Sweetened (Stevia) & Third-Party Certified
Transparent Labs Whey Protein Isolate
  1. Legion Whey+ Whey Protein Powder – Best Zero-Carb & Third-Party Certified
  1. Bulk Supplements Unflavored Whey Isolate – Best Unflavored
Bulk Supplements Unflavored Whey Isolate

Frequently Asked Questions

Does Whey Protein Spike Insulin?

Whey protein spikes insulin because of its amino acid content, not because of its sugar content. Specifically, the branched-chain amino acid leucine will cause insulin to rise to help the muscle cells take up the amino acids.

The insulin will also store glucose in the cells, helping to reduce blood sugar levels.

More Protein Powder Resources


Petersen, B. L., Ward, L. S., Bastian, E. D., Jenkins, A. L., Campbell, J., & Vuksan, V. (2009). A whey protein supplement decreases post-prandial glycemia. Nutrition journal, 8, 47. https://doi.org/10.1186/1475-2891-8-47

Anders H Frid and others, Effect of whey on blood glucose and insulin responses to composite breakfast and lunch meals in type 2 diabetic subjects, The American Journal of Clinical Nutrition, Volume 82, Issue 1, July 2005, Pages 69–75, https://doi.org/10.1093/ajcn/82.1.69

About The Author

Lauren Graham

Lauren Graham is a Precision Nutrition Level 1 certified nutrition coach. She focuses on helping busy professionals balance healthy eating and purposeful movement.  Lauren has a background in competitive swimming and is currently competing as a CrossFit athlete.  She has a passion for training, teaching, and writing. 

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