Drinking Whey Protein On An Empty Stomach (3 Things To Know)

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I’m part of several online nutrition communities, and lately, there have been a few questions about whether or not it’s good to drink whey protein on an empty stomach.

As a nutrition coach, I decided to dig into the research to see if any studies discussed this and determine what I would tell my clients if they asked me.

Here’s the short version of what I found:

Key Takeaways: Is It Better To Take Whey Protein On An Empty Stomach?

• If you’re looking to lose fat, prioritizing protein intake first thing in the morning (which may mean you consume whey protein on an empty stomach) can help reduce overall food intake throughout the day.

• If you’re looking to build muscle, hitting your protein target for the day is more important than whether you take your whey protein on an empty stomach.

• If you have digestive discomfort after taking whey protein on an empty stomach, it may be because you’re lactose intolerant or have sensitivities to the sweeteners or other ingredients in the protein powder.

What the Science Says About Drinking Whey Protein on an Empty Stomach

Studies around drinking whey protein on an empty stomach have been done for three scenarios: (1) whether someone is intermittent fasting, (2) whether someone is trying to lose weight, and (3) whether someone is trying to build muscle.

Intermittent Fasting

One reason why some people may want to take whey protein powder on an empty stomach is that they are intermittent fasting.

Intermittent fasting is a dieting approach believed to promote more fat loss by encouraging the body to burn stored body fat instead of food for fuel.

While I’m not going to talk about the pros and cons of this approach here, this can lead people to believe that they should exercise without eating anything and then take a whey protein shake on an empty stomach after training.

However, recent studies like this one show that reduction in body fat is the same whether participants train in a fasted state (eating after training) or in a “fed” state (eating before training) when the overall calorie deficit is the same for both groups. 

Takeaway: This means that choosing to eat (including taking whey protein powder) before or after training (or both) is more of a matter of personal preference and convenience.

Fat Loss

When it comes to fat loss, there may actually be some benefits to taking whey protein on an empty stomach.

Prioritizing protein intake first can help reduce subsequent food intake. In this study, a high-protein breakfast helped with weight loss by reducing food intake in later meals. 

The high-protein breakfast wasn’t specifically whey protein powder, but a whey protein powder shake or ready-made protein drink could be part of an overall high-protein breakfast.

• Related Article: 15 Bodybuilding Breakfast Ideas

Specifically looking at whey protein, this study showed that a whey protein supplement led to higher fat loss and greater preservation of lean muscle mass. The supplement was taken before breakfast and before dinner, meaning it was taken on an empty stomach.

Key Takeaway: This means that prioritizing protein intake first thing in the morning (such as taking a whey protein shake on an empty stomach) can help with fat loss.

Building Muscle

There is a lot of hype around the “anabolic” window or “window of gains.”

Some people believe it’s important to get the timing of protein intake just right relative to training to maximize muscle growth. This includes ensuring you take protein before training, so your workout doesn’t “eat your muscles.”

But, this meta-analysis (an overview of several studies) shows that total daily overall protein intake is more important than timing, including whether you take it on an empty stomach.

Key Takeaway: When building muscle, hitting your protein target for the day should be the focus.

Should You Take Whey Protein Powder on an Empty Stomach?

Whether you are prioritizing fat loss or muscle building, there are times during the day when you’re more likely to take protein powder on an empty stomach.  

First Thing in the Morning

When you first wake up in the morning, you will have an empty stomach. If you don’t have time to make and eat a big breakfast with whole food sources of protein, this can be a good time to take whey protein powder.  

Or, if you don’t have much of an appetite or struggle to eat solid foods in the morning, a protein shake or ready-made protein drink is an easier way to consume protein and calories without feeling uncomfortable.

You might also prefer not to have solid food in your stomach if you work out first thing in the morning. See my comments about taking whey protein pre-workout in the next section.

Pre-Workout

If you work out first thing in the morning, your pre-workout snack will be on an empty stomach. 

You also don’t want to feel uncomfortably full if you are working out later in the day, so it is a good idea to plan for at least 2-3 hours between your meal and your workout. This pre-workout meal may be several hours after you last ate, meaning your stomach will be empty again.

In both of these cases, a pre-workout snack consisting of whey protein and fast-digesting carbs like fresh or dried fruit, rice, pasta, or cereal is a good idea to give you energy for your training.

Post-Workout

By the time you get to the end of your workout, you will have used up your pre-workout snack, and your stomach will be empty again. If you train first thing in the morning and prefer to train fasted, your stomach will also be empty.

In these scenarios, taking whey protein post-workout on an empty stomach is a good idea. It digests quickly, so it can work to repair and build new muscle soon after training.

Combine it with fast-digesting carb sources like the ones mentioned above to further promote recovery after training.

As a Snack

Away from the training window or on non-training days, you might want to include whey protein powder as part of a snack.

Depending on how long it’s been since you last ate, this might be on an empty stomach.  

Before Bed

Some individuals also take whey protein powder before bed to maximize protein intake or help meet protein requirements for the day.

Depending on how much time passes between the last meal of the day and bedtime, this could mean taking whey protein on an empty stomach.

• Related Article: Pre-Workout On Empty Stomach: Good or Bad Idea?

Will You Get Digestive Discomfort Taking Whey Protein on an Empty Stomach?

Generally, if whey protein powder causes digestive discomfort, it is because of an ingredient in the whey protein powder and not because it is taken on an empty stomach.

If you are sensitive to these ingredients, they are likely to cause digestive problems whether you take the protein powder on an empty stomach or not.

Here is a review of common ingredients that can cause digestive discomfort:

• Lactose
• Sugar alcohols (for example, sorbitol)
• Fiber
• Allergens (for example, peanuts or soy)
• Fillers (for example, gums, thickening agents, and emulsifiers)

If you think any of these ingredients will make you sick drinking whey protein, then check out my other resources:

• Can Protein Shakes Make You Nauseous?  (Yes, Here’s Why)
• Protein Shakes & Diarrhea: Causes + Fixes Explained

You can also experience digestive discomfort based on how you consume the whey protein powder.

For example, if you chug a protein shake really quickly, it can make you feel ill.

In this case, it’s better to sip your shake slowly, taking 10-15 minutes to finish it, rather than gulping it down in a few minutes.

What To Consider if You’re Taking Whey Protein on an Empty Stomach

If you are taking whey protein on an empty stomach, here are some things for you to consider:

Type of Protein

Pure whey protein isolate has little or no lactose, but whey protein concentrate can have several grams of lactose per serving.

This means pure whey protein isolate is less likely to cause digestive discomfort if you have problems digesting lactose.

If you are sensitive to lactose, look for a pure whey protein isolate.

Brand of Protein

Different brands of protein powder can have different additives. Since protein powder is considered a dietary supplement, it is not subject to the same regulations as food.

The best way to ensure you are getting the actual ingredients in the amounts stated and no unwanted fillers that could upset your stomach are to look for brands that are third-party certified.

Fiber Content

Since too much fiber can cause digestive issues and also make it take longer for whey protein to digest, look for a product that has fewer than 3g of fiber per serving when you are taking whey protein on an empty stomach.

A common type of added fiber to look out for is inulin fiber. It can also be listed under the names oligofructose, chicory root, or chicory root extract.

Sweeteners

As sugar alcohols can cause digestive upset, especially when consumed on an empty stomach, look for either unsweetened protein powder or protein powder that is sweetened without the use of sugar alcohols.

Instead of sugar alcohols, look for other sweeteners such as sugar, stevia, monk fruit, acesulfame potassium, or sucralose, which are less likely to cause digestive upset.

Ingredients

When taking whey protein on an empty stomach, you want to ensure you’re only getting the ingredients that work for you.

For example, if you find that you are sensitive to certain thickeners like xanthan gum, avoid protein powders that contain them.

Is There a Type of Protein That’s Better for Taking On an Empty Stomach?

I like to use a whey protein powder that is a pure whey isolate powder (no lactose) and has no sugar alcohols, no added fiber, and no thickening gums such as xanthan gum.  Plus, I want it to taste great.

My top whey protein powder to take on an empty stomach is Transparent Labs Whey Protein Isolate (click to read my full review).

Other Protein Resources

• Can You Drink Whey Protein Every Day?
• Can You Take Whey Protein Without Working Out?
• Can You Use Whey Protein As A Meal Replacement?

References

Frestedt, J.L., Zenk, J.L., Kuskowski, M.A. et al. A whey-protein supplement increases fat loss and spares lean muscle in obese subjects: a randomized human clinical study. Nutr Metab (Lond) 5, 8 (2008). https://doi.org/10.1186/1743-7075-5-8

Schoenfeld, B.J., Aragon, A.A. & Krieger, J.W. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr 10, 53 (2013). https://doi.org/10.1186/1550-2783-10-53

Schoenfeld, B.J., Aragon, A.A., Wilborn, C.D. et al. Body composition changes associated with fasted versus non-fasted aerobic exercise. J Int Soc Sports Nutr 11, 54 (2014). https://doi.org/10.1186/s12970-014-0054-7