Is It a Good Idea for You to Substitute a Meal Replacement with a Protein Shake?

Posted September 2023

Is It a Good Idea for You to Substitute a Meal Replacement with a Protein Shake? - The Collagen Co.

If you want to lose weight, you’re definitely familiar with (or, at the least, have heard of) meal replacement shakes. Because these gems work.

Many studies have shown that they produce better weight loss results than traditional, calorie-restricted solid food diets.

“Better”: can we quantify this? You bet. According to a meta-analysis of 6 studies from the International Journal of Obesity and Related Metabolic Disorders, participants who adhered to a partial meal replacement plan lost:

  •   2.54 more kilograms at the 3-month mark, and
  •   2.43 more kilograms at the 1-year mark

… than those who were assigned to the conventional reduced-calorie diet plan.

But, despite that, you might still have reservations about using a meal replacement to lose weight. The most pressing one being: can't I simply substitute the meal replacement with a protein shake? It’s potentially cheaper, and would do the same thing? Hmm. Let’s see.

You can substitute a meal replacement with a protein shake

To be clear, there are no rules against swapping out a meal replacement with a protein shake for weight loss. In fact, they share 2 common benefits helpful for your weight management goals. 

#1: Low-calorie

Some background information: how your weight changes depend on your energy balance.

If you’re in a calorie: 

  • Surplus (i.e., calories consumed > calories burned): Weight gain
  • Deficit (i.e., calories consumed < calories burned): Weight loss
  • Maintenance (i.e., calories consumed = calories burned): Weight maintenance

Most protein shakes and meal replacements contain 100 to 300 calories per serving.

That's typically fewer calories than what you'd get from a meal at lunch or dinner — think pan-seared steak and a side of crispy potatoes or creamy mushroom risotto — which often runs up to 500 to 1,000 calories.

The difference can be up to an eye-watering 700 calories!

Meaning? When you replace a meal with either a meal replacement or protein shake, you’d likely consume fewer calories, increasing the chances of achieving a calorie deficit needed to lose weight.

#2: High in satiating protein

Another thing protein shakes have in common with meal replacements? Their high protein content.

Meal replacement shakes usually contain 15 to 20 grams of protein per serving; protein shakes are anywhere between 20 to 30 grams.

And … what’s that got to do with weight loss?

Answer: protein is the most satiating macronutrient.

Thanks to that property, meal replacements and protein shakes could help you stay fuller for longer, bolstering your ability to resist those pesky mid-day and pre-bedtime munchies.

Once again, this will likely reduce your overall daily calorie intake, and you should know how the rest of it goes (i.e., calorie deficit and, in turn, weight loss). 

  1. So, meal replacements and protein shakes share 2 characteristics: low calories and high in fullness-promoting protein. For now, substituting meal replacement drinks with protein shakes for weight loss is starting to sound like a really good idea.

But it’s actually unwise to do so

Huh? Let us explain.

The primary purpose of protein shakes, as their name implies, is to provide a ton of protein. They do that really well, but it often means they contain little else

Especially in terms of micronutrients: vitamins and minerals necessary for optimal health. 

And while you’d think micronutrient deficiency is something that only affects people in less developed countries with greater food scarcity, it turns out that many in developed countries — e.g., Australia and the United States — struggle to meet their daily micronutrient requirements.

Vitamin D, calcium, iodine, and iron are just a few examples of the micronutrients Australians don’t get enough of

Now, think about this. 

In general, the higher your calorie intake, the more micronutrients you’re getting. So, what happens when you slash your calorie intake by replacing your regular meals with micronutrient-poor protein shakes?

That’s right. You’re likely to end up eating even lesser amounts of micronutrients than before. 

The result could range from the slightly annoying (e.g., low energy levels) to the more worrying (e.g., a compromised immune system). 

Meal replacement shakes are different. Better at replacing meals, to be specific.

They’re designed to provide the nutrition of a full meal. That means, in addition to satiety-promoting protein, they also typically contain the appropriate blend of:

  • Micronutrients: These go a long way in bridging the gap between your intake and daily recommended levels to support vital bodily functions ranging from brain to bone to immune health, especially now that you’re eating fewer calories. 
  • Carbs and fat: For long-lasting satiety and energy (dietary fiber also has the nice little bonus of improving gut health!)


Just because you can substitute a meal replacement with a protein shake doesn't mean you should. As outlined in this article, doing so could mean missing out on things like enhanced satiety, crash-free energy, improved gut microbiome, and optimal health.

Of course, it’s perfectly fine if you’re in a pinch, and the only 3 choices you have at that point are: 1) eat nothing, 2) protein shake, and 3) ultra-processed, calorie-dense foods from the restaurant next door.

The point is simply this. Opt for meal replacement shakes for a long-term, more sustainable tool for weight loss.

*ahem* Coincidentally, we carry one of the best meal replacement smoothies for weight loss available in the market, Glow Shakes. The proof is in our ingredients:

  • 29+ grams of protein (of which, you’ll find 17.5 grams of hydrolyzed collagen peptides — so you keep the glow while losing weight)
  • A good balance of carbs and fat (~ 6 grams each)
  • 5+ grams of prebiotic fiber
  • 24 vitamins and minerals
  • MCT oil and green tea extract

Uh, what about the taste, you ask? We’ll let these customer reviews speak for themselves:

  • " This is the best meal replacement I have ever had. Other shakes have a powdery tested which I cannot stomach and the glow shakes taste delicious that you look forward to drinking it. Love the smooth texture. Chocolate is my favourite one" - Tiyana J. Verified Buyer Chocolate Milkshake Collagen Meal Replacement

  • " I love, love, love the new milkshake collagen. It mixes well, has a yummy flavour and fills you up. I have also bought the chocolate one, and it has a delicious chocolate flavour. Highly recommend." - Naomi GVerified Buyer Vanilla Milkshake Collagen Meal Replacement


Psst: we also offer bundle deals where you can save up to 15%, so you don’t have to worry about straining your wallet while sipping your way to your dream body. Shop now.


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