I Left My Protein Shake In The Fridge Overnight (Here’s The Result)

I always wondered whether you can leave a protein shake in the fridge overnight.

So I tested it.

Here was the result:

You can safely leave a protein shake in the fridge overnight, as long as your fridge is cold enough (40 degrees F or colder). For the best results, mix your protein shake with water or milk, not juice, and don’t add any extra ingredients like fresh or frozen fruit or other supplements like creatine.

If you’re planning to leave your protein shake in the fridge, be sure to follow my tips below so that you don’t end up with a gross, slimy science experiment instead of a protein shake.

Key Takeaways

  • Leaving a protein shake in the fridge overnight can change its taste, texture, smell, and color
  • It’s best to drink your shake within 24 hours, but you can leave it in the fridge for up to 72 hours if needed.

Reasons For Making Protein Shakes Ahead Of Time

To Save On Time

Lots of people find that making meals and snacks ahead of time, including protein shakes, saves them time throughout the day, especially if they have a hectic schedule.  

This seems to be especially true for people who like to get their workouts in before work.

Making a protein shake the night before can make it easy to roll out of bed, throw on some sweatpants, grab the shake, and head to the gym.

Meal Planning & Prep To Meet Nutrition Goals

Many people find it easier to hit macro targets when they plan their meals and snacks ahead of time to ensure that they are getting enough (but not too much) of each nutrient, especially protein.  

For example, if I know that my total daily protein target is 150 grams, I might decide to have two scoops of protein powder, totaling 50g of protein to meet my protein target. If I make these shakes ahead of time, I can easily grab and go during the week and stay on track with my daily protein target.

This is similar to batch cooking for meal prep and having pre-made meals ready to go in Tupperware or glass containers.

5 Factors That Determine Whether It’s Safe To Leave A Protein Shake In The Fridge

5 factors that determine whether it’s safe to leave a protein shake in the fridge

The 5 key factors to safely store your protein shake overnight are:

1. Temperature

One of the top considerations for whether it’s safe to leave a protein shake in the fridge is the temperature of the fridge.

If your fridge isn’t cold enough then your shake may not be safe to consume because warmer temperatures make it easier for bacteria to grow.

For best results and to ensure the safety of your protein shake, make sure that your fridge thermostat is set at 40 degrees Fahrenheit (4 degrees Celsius) or colder.

2. Time

Another thing to consider is how long you will need to leave your protein shake in the fridge.

If you leave your protein shake in the fridge for too long then the quality, texture, taste, and smell of the shake will be greatly diminished.

I recommend drinking your protein shake within 24 hours of mixing it and avoiding leaving your shake in the fridge for more than 72 hours (3 days).

3. Container

How you store your protein shake in the fridge will also play a role in how safe it is to consume over time because improperly stored shakes let in air that will start breaking down the shake.

It also provides an opportunity for airborne particles like bacteria or germs to come into contact with your shake.

Your shake will be safe for longer if it’s stored in an airtight container with a secure lid, like a glass or metal water bottle with a water-tight screw-on cap, or a shaker cup with a tightly fitting lid.

Important: Do not leave your shake in an open glass or cup.

4. Other Ingredients

Adding additional ingredients like fruit, vegetables, nuts, seeds, or peanut butter will reduce the amount of time that you can safely store your protein shake in the fridge because some ingredients hold up better than others.

If your shake has added ingredients, aim to drink it within 24 hours to ensure a higher-quality protein shake.

5. Other Supplements

If you like to add other supplements to your protein shake, like creatine, you’ll want to try to drink your protein shake on the same day because creatine is not stable when it’s dissolved in a liquid.

The more acidic the liquid, the more quickly creatine breaks down, so I recommend sticking to water or milk and avoiding fruit.

Also, the higher the temperature, the faster creatine breaks down, so be sure to get your shake into a cold refrigerator right away, and drink it as soon as possible after you take it out of the fridge.

Leaving A Protein Shake In The Fridge Overnight: My Results

Here are my results from leaving two different protein shakes in the fridge overnight. 

  • Shake 1: whey protein isolate with water, prepared in a shaker cup.  
  • Shake 2: whey protein isolate blended with cashew milk and blueberries in a Vitamix blender.

Shake 1: Before & After

SHAKE 1 BEFORE

Shake 1 (Whey Protein Isolate + Water) “Before”
Shake 1 (Whey Protein Isolate + Water) “Before”

I put the lid on the shaker cup and left this in the fridge overnight. Here is what it looked like the next morning:

SHAKE 1 AFTER

Shake 1 (Whey Protein Isolate + Water) After
Shake 1 (Whey Protein Isolate + Water) After

The Results

If you look closely, you can see that there aren’t quite as many little bubbles along the top, and in the picture on the right you can sort of see that the shake has separated a little bit.

But, other than that, it’s almost identical to the “before” photo and a quick shake with the lid on made it just like the original. It also smelled and tasted the exact same as the night before.

Here’s how I would score the shake out of 5 compared to its original state:

  • Taste: 5/5
  • Texture: 4.5/5
  • Color: 4.5/5
  • Smell: 5/5

Shake 2: Before & After

SHAKE 2 BEFORE

I put the snap-on lid on this bottle and left it in the fridge overnight. Here is what it looked like the next morning:

SHAKE 2 AFTER

Whey Protein Isolate + Frozen Blueberries + Cashew Milk “After”

The Results

As you can see, it went from a beautiful and appetizing purple color to this gross gray color. 

The texture also changed, from smooth and creamy to a more foamy, watery consistency, and the shake separated into mostly foam on top with liquid at the bottom, which you can see at the bottom of the bottle in the “after” photo.

I snapped the lid back on and gave it a vigorous shake.  The flavor was actually about the same as the night before, even though it didn’t look as good, but the texture wasn’t as smooth and creamy, mainly because the frozen blueberries had melted and left it watery.

Here’s how I would score the shake out of 5 compared to its original state:

  • Taste: 4.5/5
  • Texture: 3/5
  • Color: 1/5
  • Smell: 4/5

Would I Leave A Protein Shake In The Fridge Overnight Again?

I wouldn’t leave a protein shake in the fridge overnight again if I didn’t have to because the fresh taste and texture are worth taking the time to prepare after my workout. That said, if I was short on time then I would consider mixing water and protein powder in a shaker cup the night before.

If you are pressed for time and you know that preparing your protein shake the night before is going to make your life easier then here are my top tips for getting a high-quality shake the next day:

  1. Mix with water or milk only: do not mix with juice, especially if it is an acidic fruit juice like orange juice. The acid in juice can react with the protein powder and create a very unpleasant shake.
  1. Do not add fruit: almost all fruits are at least slightly acidic, and the acid can react with the protein powder and give your shake a funky taste, texture, and smell the next day.
  1. Use an airtight container: ensure that you have a bottle or shaker cup with a tight-fitting, secure lid. This will reduce the amount of air that can react with your shake, and will also make it easier to shake up your mixture again before you drink it.
  1. Refrigerate your shake: store your shake in a fridge at a temperature no higher than 40 degrees Fahrenheit (4 degrees Celsius) to ensure your shake is preserved properly overnight.
  1. Shake or blend again before drinking: Shake your drink vigorously before consuming, or if you are able, put it in a high-speed blender with a little ice for the best results.  

This isn’t always an option if you are not at home or you are truly pressed for time, but it does take less time than making the entire shake from scratch so it is a good option for some people.

Frequently Asked Questions

How Long Can You Leave A Protein Shake In The Fridge?

You can leave a protein shake in the fridge for up to three days (72 hours) at most, but you should plan to drink your shake within 24 hours. This is especially true if it contains additional ingredients such as fruit or vegetables, especially acidic fruits like citrus that can react with the protein powder.

Will A Protein Shake Go Bad In The Fridge?

Yes, once a protein shake is opened (if it’s a ready-made shake) or mixed (if it’s powder and liquid), it will go bad in the fridge after a few days. You have up to 72 hours to drink it before it goes bad, but ideally, you should drink a refrigerated shake within 24 hours.

What Temperature Should You Store A Pre-Mixed Protein Shake At?

You should store a pre-mixed protein shake at a temperature of 40 degrees Fahrenheit (4 degrees Celsius) or lower.

How Long Will A Protein Shake Last If You Don’t Refrigerate It?

A protein shake will last no more than two hours if you don’t refrigerate it. Be sure to drink your shake within 2 hours of opening it/mixing it if you’re not able to refrigerate it.


About The Author

Lauren Graham
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.