How Long Does a Protein Shake Last After Mixing?

Protein is an essential macronutrient needed to repair, recover, build muscle, and perform other vital physiological processes. Based on the most recent body of literature, the optimal daily amount of protein for those wanting to maximize muscle growth is between 1.6–2.2 g/kg/day (~0.8-1.0 grams/lb/day).[1]

If you’re a 200lb guy that’s relatively lean, consuming 200 grams of protein from whole foods alone is quite challenging, which is where protein powders come in handy. Not to mention, when you’re traveling or on the go, high-quality protein sources are hard to come by, which is one of the reasons why protein shakes are so popular.

Although you can buy ready-to-drink protein shakes from convenience stores, gas stations, and grocery stores, they are a lot more expensive than buying a 2lb or 5lb tub of protein powder and mixing it yourself.

Because it’s quite common for people to pre-mix their protein shakes but not consume them straight away, one of the most commonly asked questions in regards to protein powders is, “how long does a protein shake last after mixing?”. Not to mention, some people prefer to mix their protein with greek yogurt or oats (i.e. overnight oats, smoothies, etc.) for a quick and easy meal.

The answer to this question depends on various factors such as what the protein powder is mixed with (milk or water), whether it’s refrigerated or left at room temperature, and if there are any other active ingredients added to the protein powder. In this article, we cover various protein powder scenarios and give you estimates of how long the mixture or protein shake will last.

How long does a protein shake last after mixing?

It’s important to note that there are no studies assessing the time protein shakes will last for after being mixed with water or milk. With that said, if the protein shakes are kept in a refrigerator, most agree that they will stay good for 48-72 hours after mixing.

However, there are a few scenarios in which you should try to consume the protein shake in a shorter time period.

Keep reading to find out if one of these scenarios applies to you!

Scenario #1 – How long does a protein shake last after mixing if it contains digestive enzymes?

It’s quite rare to see a ready-to-drink protein shake that contains digestive enzymes, with the exception of lactase. Once digestive enzymes are introduced to a solution (i.e. liquid), they become activated. In other words, the digestive enzymes will begin to break down the protein molecules, turning them into smaller chains of amino acids.

Digestive enzymes are often added to protein powders as an extra feature since they may help reduce gas and bloating, support digestion, and increase the amount and rate of nutrient absorption. More importantly, digestive enzymes are stable in powder form, but as soon as they are introduced to liquid, protein powders immediately begin breaking down.

Some of the most common digestive enzymes that are added to protein powders include:

• Protease – breaks down protein
• Lipase – breaks down lipids
• Cellulase – breaks down cellulose
• Amylase – breaks down starches
• Lactase – breaks down lactose
• Papain – breaks down protein
• Bromelain – breaks down protein
• DigeZyme® – registered trademarked digestive enzyme blend
• DigeSEB® – registered trademarked digestive enzyme blend
• ProHydrolase® – registered trademarked digestive enzyme blend

If your protein powder contains digestive enzymes, such as the ones listed above, you should drink the protein shake within 20-30 minutes after mixing. If you let the protein shake sit in the solution, the digestive enzymes activate and start to break down the protein as well as the other nutrients contained in the powder. Not only will this negatively affect the taste, but it may reduce the protein quality.

Scenario #2 – How long does a protein shake last after mixing if refrigerated or left at room temperature?

If your protein powder doesn’t contain digestive enzymes, it’s completely fine to mix it and place it in the fridge. As long as it remains cold, a refrigerated protein shake will last anywhere from 48-72 hours. If you can’t refrigerate the protein shake after it’s mixed, you should consume it within 20-30 minutes after mixing, regardless of whether it has digestive enzymes or not.

With that said, if your protein powder is plant-based, it may last up to 45-60 minutes at room temperature since it won’t spoil as a dairy-based protein would. Keep in mind that the protein powder may not taste great if it sinks to room temperature. Many supplement companies recommend mixing protein powder in cold water, milk, or a milk substitute.

Scenario #3 – How long does a protein shake last after mixing with water or milk?

If you mix protein powder with milk, drink it within 20-30 minutes after mixing if not refrigerated because the milk will begin to spoil, which may lead to food poisoning. If you prefer to mix your protein powder, especially if it’s a plant-based or vegan protein powder, with a milk substitute, such as almond milk or cashew milk, or water, it may last up to 45-60 minutes. 

However, over time a protein shake made with water or milk substitute will begin to go bad, especially if not refrigerated. Similar to the previous scenario, consuming the protein shake shortly after mixing ensures the best taste, digestion, and effectiveness.

Scenario #4 – Protein powder type

There are various types of protein powders on the market, but the most common types are:

• Dairy-based – whey protein isolate, whey protein concentrate, hydrolyzed whey protein, milk protein isolate, and casein
• Egg-based – egg white protein
• Plant-based – pea protein, brown rice protein, watermelon seed protein, mung bean protein, pumpkin seed protein
• Blends – contain 2 or more types of protein powders

Any dairy-based or egg-based protein powder will go bad quicker than a plant-based or vegan protein powder because it’s more likely to spoil. Make sure to leave it in the refrigerator or consume it quickly after mixing. Vegan protein powders will stay good for a slightly longer period of time, but it also depends on what other ingredients they contain, such as creamers, digestive enzymes, etc.

When’s the best time to consume protein powder?

One of the biggest myths that surround protein powder is the best time to consume them. It’s often stated that you have to consume a protein shake directly after a workout, or you’re wasting your time. However, that couldn’t be further from the truth. In reality, you can use protein powders any time of the day. In fact, you don’t even have to make a protein shake!

Protein powder can be used in various baking recipes, blended into a smoothie, or added to oatmeal, cream of rice, or greek yogurt. Protein powder is a very versatile product, and the days of slamming a protein shake as soon as you finish your last set is a thing of the past.

With that said, consuming protein and carbohydrates after training is a good idea to stimulate muscle protein synthesis and kickstart recovery.

Final Thoughts

Protein powder is convenient, tasty, versatile, and an efficient way for you to hit your daily protein intake. In terms of muscle building, protein powders are one of the most recommended supplements. The protein powder sector continues to grow in popularity, especially with the various types that are available. At this point, regardless of your diet, there’s a protein powder that will meet your needs.

One of the biggest pros of protein powders is that they are fairly budget friendly and easy to transport. Compared to making a meal, it takes way less time to mix up a protein shake and get out the door. What’s more, it’s much cheaper to mix your own protein shake than to buy a ready-to-drink from the store.

If you want an affordable and tasty way to hit your macros, it’s a good idea to keep protein powder, a shaker, and some water on hand. Just make sure you don’t let the protein sit in a shaker for too long, or else it can go bad, especially when mixed with milk, not refrigerated, and if it contains digestive enzymes. A spoiled protein shake will likely have an off-smell to it, so steer clear if you think the protein shake was left unrefrigerated for too long.

References

1. Iraki, J. et al. July 2019. “Nutrition Recommendations for Bodybuilders in the Off-Season: A Narrative Review.” Sports (Basel), vol. 7(7):154. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6680710/