Does Mass Gainer Expire or Go Bad?

January 9, 2024 |

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In this article, we’ll discuss how long mass gainers last and what effects they may cause if you consume them after expiration.

Have you regained the motivation to gain some mass and just discovered your good ol’ mass gainer lying in the kitchen cupboard? It is understandable why you won’t want to throw away an unused purchase. But there are some things you need to consider.

Although keeping desiccated powders safe from hydration may increase their shelf life. But still, there are some inherent factors (e.g., lactase in dairy protein) that may eventually cause nutrient degradation.

Not to mention that degradation of quality with the passage of time is an inevitable part of most consumables.

So, keep reading to find out the details.

How Many Days Does a Mass Gainer Last?

A sealed bag of mass gainers may last for 2-3 years. Whereas if you open the bag, it may remain edible for 2-3 months maximum.

However, to prolong the shelf life, these powders should ideally be stored in a cool (normally 21oC), dark and dry place where humidity is not more than 35%-60%.

But be careful that refrigerators and freezers are a big no for storing unprepared powders.

Now, why does the expiration date vary in both cases?

Unopened bags last longer because mass gainers are, in fact, dehydrated and concentrated powders of stable ingredients like protein isolates, creatine, and gums.

Moreover, they may also contain certain additives like calcium chloride, ascorbic acid, or xanthan gum that have a preservation effect on the products.

So, the lack of moisture and the presence of preservatives reduce the chance of microbial growth (bacteria, mold).

And when you break that seal, air and moisture enter the product.

Since mass gainer powders are still nutrients, so this creates an ideal environment to support microbial growth, and the proteins and nutrients will start degrading.

Hence their shelf life is reduced to around one or two months.

But since these supplements mostly offer 6 to 12 servings per bag and are supposed to be taken daily so, hopefully, you will chug them down before they go bad.

What is the Shelf life of Mass Gainers?

shopping mall shelf

Unprepared mass gainers may have a shelf life of 2 months to 3 years. In contrast, prepared shakes will only last for a maximum of 2 hours on the shelf.

In the first case, the ingredients’ stability contributes to the longer shelf life of unmixed powders.

For instance, studies have shown that whey protein can last for nine months at room temperature and 19 months at 210C.

Apart from the nutrients, in case your mass gainer has creatine in it, even then, it will remain stable because studies prove that creatine lasts even longer than 2-3 years.

Furthermore, artificial sugars are the next core ingredients in the mass gainers, and they don’t expire either.

Compared to this, adding water or any other liquid to the powders makes the ingredients unstable due to the different solvent reactions and reduces their shelf life.

Hence, although adding water is important for activating the mass gainer ingredients, setting aside the prepared shake for a longer time may ruin its effectiveness.

For instance, creatine will start to break down into the useless by-product creatinine. Similarly, the amino acids in the proteins undergo conformational changes, and they may start to taste unpleasant and become difficult to digest.

Additionally, dissolved nutrients pave the way for microbial spoilage.

Is it Safe to Use an Expired Mass Gainer?

Consuming expired mass gainers isn’t deadly. Still so, it might lose its taste and benefits. If you analyze the mass gainer content, you will see that it is basically predominated by carbohydrates and protein.

However, the carbohydrates in the product are mainly starch, sugar, or dietary fiber, which don’t have an expiry date.

Hence, the protein may be the only component that could make these macronutrient powders go off after the expiry date as it is most susceptible to deterioration.

Therefore, researchers have evaluated the shelf life of different whey protein powders.

And according to one study, the whey protein may undergo Millard browning at varying rates under different storage conditions.

If you are wondering what Millard browning is, it is the nonenzymatic protein modification due to the reaction between lysine and lactose in whey protein.

Consequently, due to the reduction of lysine, the mass gainers may lose their nutritional efficiency and will no longer be complete in amino acids.

Other effects that may occur are bad taste, changes in color and texture (clumps), decreased solubility, vitamin loss, and increased acidity.

Even so, these changes will at most render your mass gainer inefficient.

But since macronutrient powders are already hard to digest, consuming them after expiration may mess with your digestive process even more and cause side effects.

Nonetheless, dairy-derived proteins may deteriorate faster than plant proteins.

Additionally, if your powder has a putrid smell or if you can see mold in it, then you definitely need to avoid consuming it after the expiry date.

On top of the scientific jargon, here are some user recommendations on your question:

A user ‘ChargeItToTheGame420’ initiated this Reddit thread to ask if an expired but sealed mass gainer can be consumed.

The user’s opinion reflects that it is A-okay to consume expired mass gainers, but it may taste yuck.

Furthermore, one user replied that mass gainers are fine for consumption as long as they have not expired for more than three years.

However, users had mixed opinions with regard to using expired unsealed mass gainers.

Half repliers on the bodybuilding forum suggested the conversation starter use it. The other half indicated the risk of the development of botulism or diarrhea.

Here again, the users warned that the supplement might taste gross.

What would happen if you consumed an expired mass gainer?

Consuming expired mass gainers might cause gastrointestinal distress. You may expect symptoms like diarrhea, indigestion, stomach cramps, vomiting, bloating, stomach discomfort, etc.

Mass Gainer cta


To conclude, untouched mass gainers are fit for use until two years from the manufacture date. Nonetheless, it is better to avoid using them after they have passed this duration.

However, you may not find expiry dates on your supplement always.

So, in this case, you may contact your vendor to know the manufacture date. But if it is hard for you to throw away your unused supplement and if you want to use it, then keep in mind that it may cause digestive disturbances.

Important Disclaimer: The information contained on MAX HEALTH LIVING is intended for informational and educational purposes only. Any statements made on this website have not been evaluated by the FDA and any information or products discussed are not intended to diagnose, cure, treat, or prevent any disease or illness. Please consult a healthcare practitioner before making changes to your diet or taking supplements that may interfere with medications.

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