In the world of weight loss, one of the most common methods people choose to pursue is the shake. Weight loss shakes and slim shakes have been popular for decades, from brands like SlimFast (which is 45 years old! It was founded in 1977, fun fact.) to modern new-wave meal replacements like Soylent or Huel.
A question you probably have, though, is whether or not they need to be refrigerated. So, do they? And if you don't keep them chilled, what happens?
Do Shake Mixes Need to be Refrigerated?
First of all, it's important to recognize that slim shakes typically have three different forms. We'll talk about all three of them here, starting with the simplest option: a mix.
A slim shake mix is something like our Slim Shakes. They are, basically, just a powdery mix of protein powder (ours uses soy, pea, and rice proteins), some cocoa powder for flavoring (or another flavoring if you're getting vanilla or strawberry), and some other additives. In our case, we include powdered MCT for additional health benefits, and a little bit of stevia for sweetness. Other mixes will have a different set of ingredients.
As a dry, powdered mix, you generally don't need to refrigerate these kinds of products. In fact, it might actually be better not to, depending on your climate.
A powdered shake mix like our Slim Shakes "go bad" due to the inclusion of moisture. If moisture makes its way into the package, it can clump up and be more difficult to dissolve in milk or water, making it more difficult and less pleasant to drink. You can still stir it up and break up the clumps – a shaker bottle works wonders – but it will be harder to get a smooth shake.
On the other hand, the ingredients don't really spoil the same way a liquid might. They can still lose potency, and they can go bad over time. However, consider: we sell tubs with nearly a month's worth of daily meals, meant to be left in a cupboard or on a shelf. That's a month of exposure to room temperature and humidity, and the powder will be fine.
If you put it in the fridge, it will be colder, but nothing else will really change. The exception is if you live in a climate where moisture can accumulate in your fridge. In that case, condensation might accumulate in your tub, and clump up the mix faster.
Suffice it to say that no, you do not need to refrigerate a slim shake mix.
Do Pre-Packaged Shakes Need to be Refrigerated?
The second of three forms of slim shake is a pre-mixed liquid shake. These are the kind you typically find in four-packs on shelves in the pharmacy or breakfast aisle at your local grocery store. They're already liquid, a suspension of the same kind of mix as the powders above, except they're pre-mixed with water or some kind of shelf-stable milk substitute like soy milk or even normal milk.
These shakes are shelf-stable. This means they're fine to sit on a shelf for a while, at least as long as the duration of their expiration date.
Keep in mind, too, that they have likely already been sitting out for days, weeks, or months in between being packaged at the manufacturing facility, being shipped in a non-refrigerated truck to their destination, and sitting in a backroom waiting to be put out on shelves, on top of whatever time they spent on the shelf before you bought them.
If sitting at room temperature would hurt them, they would already be ruined.
Now, there's always a chance that these shakes could need refrigeration, depending on the brand you buy. Simply think about where you bought it. Was it in a cooler or freezer when you bought it? If so, put it back in that location in your home. If it was sitting on a shelf (which most of them will be), they don't need to be refrigerated.
There's one caveat to this: once you've opened the shake, if you don't finish it, you should refrigerate it.
See, the reason these shakes are shelf-stable is that they're purified and isolated when they're sealed. Any microbial intrusion in the shake is cleansed before it's sealed. Once you open it, all bets are off. And, what's better to grow bacteria than a protein and sugar-rich environment?
This is why most shakes will have instructions like "finish or discard within two hours of opening." If you let it sit longer, it might be fine for a little while, but you risk it fostering mold or some other kind of weird microbe. Obviously, you don't want to drink that.
Do Home-Mixed Shakes Need to be Refrigerated?
The third way you might have to deal with a meal replacement shake or a slim shake is when you mix it up at home.
Normally, products like our Slim Shakes have you scoop out a tablespoon of mix, mix it with a cup or so of water or milk, shake or stir it up, and drink it on the spot.
What if you want to mix up a shake and drink it later, like for lunch? What if you want to mix up a big batch of it and pour yourself a cup every morning?
These aren't really within the guidelines of the products, so it's difficult to say exactly what you should do. However, we can say one thing: you will almost always want to refrigerate a shake you mix at home. Adding moisture to a nutrient-rich slurry and leaving it out at room temperature is just begging for microbes to invade and infest it. This is even more likely if you're dealing with something like milk. A more shelf-stable liquid like water or soy milk is a little safer, but it's still not something we would consider safe.
This goes double if you're adding additional ingredients to your shake mix to make a smoothie, like peanut butter or fruit.
Now, if you forget and leave a cup of your shake out on the counter all day, is it going to kill you? Nah. At worst, it will generally just taste off, or have a bad texture, depending on the ingredients you put in it. If you've left it out for a week, though, we recommend just discarding it.
Oh, and consider this a disclaimer: if you leave a shake out and end up with food poisoning or something, it's not our fault! It's probably safe, but not definitely safe, so if you're worried about foodborne illness or something that aggravates your stomach, toss it out. It's not like 1/30th of one of these shake mixes is all that expensive.
Can You Drink a Slim Shake at Room Temperature?
While we wrote everything above based on the idea that a slim shake might be exposed to microbes and "go bad" if it's left out on the counter, that's not the only concern you might have. Another might just be whether or not you can drink a shake when it's at room temperature.
The truth is, it's fine, but not great. What do we mean?
Slim shake mixes usually have a few ingredients that have odd aftertastes or might not taste all that pleasant when you can taste every ingredient. For example, SlimFast has canola oil in it, which you wouldn't really consider part of a beverage under normal circumstances.
When you chill a shake, you dull your taste buds when you drink it, which helps reduce the strange tastes you might get from drinking a shake. They are, frankly, just a bit tastier when you drink them cold.
Plus, of course, you can turn them into smoothies. Add a scoop of our Slim Shake mix to a batch of frozen fruit, ice chips, simple greens, or even some nut butter, and blend it all together. When you do that, you're really just adding a bit of chocolate flavoring and protein powder to your mix.
So, the truth is, yes: you can drink a shake at room temperature. However, most of these shakes recommend drinking them cold because they taste better chilled. If you're just going to chug it in a few seconds and move on with your day, it doesn't really matter all that much. If you prefer to linger and enjoy your shake for breakfast in the morning, chilling it will make for a better experience.
So, this one mostly comes down to personal preference.
Can You Drink a Slim Shake Hot?
What about the opposite? Can you drink a slim shake hot?
This is an odd one. The answer is a qualified yes.
See, some shakes – Premier Protein's Oats line, for example – are even made to be heated up as a hot morning beverage to accompany coffee or a small meal. You can drink it chilled, at room temperature, or heated up.
The trick is, you need to heat it up the right way. You can't just pop a bottle in the microwave; you'll melt the plastic or burn the cardboard packaging. Obviously, that's bad, both for the cleanliness of your microwave and for the opportunity to not drink melted plastic as part of an unbalanced breakfast.
Instead, you'll want to pour the shake into a cup you can microwave safely (a ceramic mug works great for this) and heat it up slowly so it doesn't get scalding. You don't want to burn yourself for breakfast either, after all.
There are some milk alternatives that can do weird things when you heat them up too, so be careful of that. Mostly you just want to make sure you're stirring whatever you heat up so it doesn't separate or end up with overheated spots.
Will a Slim Shake be More Effective Cold?
Here's a bit of an interesting question. Can a slim shake be more effective (at filling you up or at helping you lose weight) if it's cold?
The answer to this one is a little more nuanced than you might expect. It's a little something like "yes, but barely."
See, when your body is cold, it wants to warm up. It does this to help maintain body temperature equilibrium, keep your organs warm enough to function, avoid cellular damage, and so on. You might notice that you shiver when you're cold; that's your body forcing motion on you to warm up, if even a little bit.
The same can happen when all you're doing is eating something cold. Your body wants to keep your body temperature up, so it has to do something. There's also something called "brown fat" that your body produces to burn for heat, which further helps you burn energy.
Now, is it meaningful? Not really. You might burn an extra calorie or ten when you drink a cold shake over a warm one, but that's not going to add up very quickly. Most of the tangible "being cold loses weight" results come from weeks of exposure to low temperatures, not a few minutes when you're eating breakfast. Of course, it won't hurt.
So, there you have it: everything you wanted to know, and plenty you didn't, about how temperature interacts with slim shakes of various kinds.
Really, what it all comes down to is three things:
- If it's a powder, store it in a cool, dry place and do whatever you want with it.
- If it's a liquid, and it's sealed, it's fine on the shelf unless it says otherwise.
- Follow the instructions on the package. If it says to refrigerate it, refrigerate it. If it says only to refrigerate after opening, you can keep it on a shelf until you open it.
Really, just remember that food safety is taken quite seriously, so instructions will be given on how to best and most safely store your meal replacements.
What's your favorite type of slim shake? Do you like yours refrigerated, pre-packaged, or potentially hot? Have you tried out one of our Slim Shakes? If so, how'd you like it? Be sure to leave all your thoughts and stories in the comments section down below! We'd love to hear what you all have to think!