Does Mass Gainer Expire and Go Bad?

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Written By
Andy Williams
Last Updated on

If you’re wondering whether or not mass gainers expire and go bad, then this article is for you. When you think of popular bodybuilding foods, such as fresh chicken, steak, and fresh fish, they typically expire quite soon after purchase and can’t safely be used after the expiration date.

But is the same true for weight gainers? Let’s find out!

Does Mass Gainer Expire?

An image showing loads of mass gainer products

So, does mass gainer expire? Yes, mass gainer does expire and go bad, just like any other supplement. Each tub of mass gainer that you buy will have an expiration date printed on it somewhere, which is usually dated between 6 and 12 months after you purchase it.

Unless your mass gainer powder has been stored incorrectly, then it should always be fine to use within the expiration date. However, if you’ve not closed the bag properly or have left the lid off the tub, then the powder will naturally start to spoil faster.

The good news is that mass gainer, like protein powder, tends to stay relatively fresh beyond its expiration date. So, if the powder has been stored correctly, then you might be able to use it for a couple of months after the expiration date.

However, since weight gainers typically have more ingredients than protein powder, they might not last quite as long after the expiration date before going bad. So, as always, you need to inspect the powder before using it if the expiration date has passed. More on that in a sec.

How Long Does Mass Gainer Last Before Going Bad?

An overhead view of some expired weight gainer

Generally, mass gainer will start to go bad a few months after its expiration date, depending on how it’s been stored and the ingredients it contains.

Unlike protein powder, mass gainer is high in carbohydrates. And if your powder contains ingredients like oats, then it might start to spoil earlier than usual after the expiration date has passed.

To keep your weight gainer as fresh as possible, always ensure that the seal on the bag is completely fastened. And if you have a tub, make sure that it’s screwed on really tightly. You can always store your mass gainer in airtight jars instead, but this might be impractical if you have a lot of powder.

Can You Still Drink Expired Mass Gainer?

A man drinking some expired mass gainer

Yes, you can still drink expired mass gainer if it’s been stored correctly and has no visible signs of spoil (more on those in a sec). 

But even though some mass gainers might be safe to consume after the expiration date, the protein quality could start to degrade, meaning that you might not be getting the full muscle-building benefits of the supplement.

If the powder has started to clump, changed colour, or smells bad, you should throw it away and buy a new batch.

On the other hand, if it’s a couple of weeks after the expiration date and the powder looks fine, then you could do a quick taste test (just put a small amount of powder on your tongue) to make sure that there’s no foul taste. If the powder passes the taste test, then you’re probably good to go! But be quick, because weight gainers don’t last forever!

Why Do Weight Gainers Go Bad?

The expiration date for a mass gainer

Weight gainers go bad due to a process known as Maillard browning, whereby the protein reacts with the sugar in the powder, something that’s a bigger concern for mass gainers as opposed to protein powders due to their higher carbohydrate and sugar content.

Lysine is usually the first amino acid to get destroyed, meaning that the overall protein quality will be much lower. [1]

If you look at most information online, the advice is pertaining to protein powders and not mass gainers. However, some mass gainers, for better or worse, are pretty high in sugar, so they’re more likely to lose the lysine, meaning that the protein would no longer be a complete protein and would thus have greatly inferior muscle-building capabilities.

It’s for this reason that I don’t recommend using mass gainers beyond the expiration date. While your weight gainer might still taste okay, it’s not worth it if you’re a serious lifter because there’s a good chance you’ll just be consuming a bunch of empty calories due to the degraded protein.

Related Mass Gainer Questions:

The Verdict On Mass Gainer Expiration

A row of weight gainer scoops

As we’ve learned, mass gainers expire just like protein powder or any other nutritional supplement. 

However, due to their high carbohydrate content, weight gainers typically expire faster than protein powders because they naturally have more sugar, which leads to a process called Maillard browning, whereby a critical amino acid—lysine—gets destroyed, rendering the protein incomplete and ineffective.

So, while you might need to throw your current mass gainer tub or bag away if it’s expired, there is some good news: you now have the opportunity to buy an even more effective supplement with higher-quality ingredients. So, stick around on my website to check out all the products that I’ve tested.

A picture of Best Mass Gainer UK founder, personal trainer Andy Williams
Andy Williams
Andy Williams is a UK-based personal trainer and bodybuilder who coaches gym-goers of all levels using proven evidence-based techniques in strength training, nutrition, and supplementation. He’s tested over 70 different mass gainers for their ingredient quality and muscle-building effectiveness and regularly shares his findings in his mass gainer reviews.
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