Before you start on the shakes, there’s probably some questions that you want answering, such as “Are protein shakes good for you?” and “Do I really need them?”. It can be hard to get the exact information you need, so we’re here to help you out.

Most people consume protein shakes to increase muscle mass, strength, and improve physical performance.1 Here, we examine the way that protein shakes work, whether they are good for you, and debunk some common myths about this popular post-gym drink.

In this article, you’ll find:

How Do Protein Shakes Work?

Protein shakes provide extra dietary protein to help build muscle after exercise, and prevent loss of muscle during weight loss or due to the aging process.2 When you consume a protein shake after a workout, you’re providing the nutrition building blocks your muscles need to recover and rebuild.2

Protein shakes work in three ways: by building muscle, preventing muscle damage, and promoting recovery in endurance exercise.3

Are Protein Shakes Good or Bad for You?

Protein shakes are a quick and efficient way to get a large dose of protein before or after a workout. If you’re a highly active individual, you need more protein than a sedentary person, and protein shakes are a good option at any time of the day.3

Protein shakes can also be a good option for someone who is active and trying to lose weight, since some food sources of protein like red meat are high in calories and fat. Protein shakes are regarded as safe for healthy individuals.4 Since protein takes longer to digest than carbohydrates, it makes you feel more satisfied for longer and can prevent overeating.5

Who are protein shakes good for?

Protein shakes are clearly beneficial for athletes and those who work out to build muscle, lose weight, or increase endurance.3 When it comes to weight loss, protein shakes can even be a highly convenient way of maintaining a  high protein diet without unwanted calories.

Protein shakes can be made simply from water and a powdered protein supplement, making them very convenient for people on the go.

In addition to  the role of protein in workouts and weight loss, protein shakes can be useful in other instances, too. When someone is recovering from a major injury or surgery, their need for protein may be greater, and protein shakes can be easier to consume than large quantities of protein foods.

Other people who may benefit from protein shakes are those who don’t have time to consume a full meal and need a protein source on the go, or those who are strict vegans or vegetarians  who may struggle to get enough protein from their diet alone.

Do protein shakes fill you up?

Protein shakes can  either fill you up or just add to your daily nutrition, depending on the type of protein you’re using and what you consume it with. For example, using a protein supplement alongside frozen fruit and a healthy fat source could make a smoothie to replace a meal, while using it simply mixed with water would be less filling.

The content of protein shakes can vary greatly, so check the label for calorie, fat, and sugar content to help you make a decision. Those that are higher in calories will be more filling than a low calorie or sugar-free version. You can always increase the calories of your shake (and protein levels too) by mixing the supplement with milk instead of water.

Do protein shakes make you fat?

Protein shakes may not be something you need to consume every day. Just like any other source of calories, consuming more that you burn will lead to weight gain in the long run. If you already have lots of calories and protein coming from your food, and you consume extra protein shakes, you m gain weight.

If weight gain is your goal, protein shakes can be a lower-fat and lower-carb option (based on the supplement you choose) to help you gain lean mass instead of fat.3

Do protein shakes make you bloated?

Protein shakes in general probably won’t make you feel bloated, but it might be a side effect of other ingredients in your shake or your diet. Many high protein products also contain extra fibre to help you feel full, which can cause gas and bloating, so if this is a concern for you, opt for a protein shake without added fibre.

Since protein does slow the digestive process, your stomach may feel fuller (or slightly bloated) than after a meal of pure carbohydrates. If you’re feeling bloated, try keeping you shakes simple (with few added ingredients) and add water instead of milk (since some people are lactose intolerant).

Do protein shakes go off?

The shelf life of a protein shake depends upon the type of shake you choose. You typically want to consume your shake pre- or post-workout anyhow, so it’s best to mix it right before you drink it.

The pre-mixed refrigerated protein shakes usually don’t last very long (even in the fridge) because they have ingredients that spoil quickly. If you purchase a protein shake in powdered form, check the label for the recommended shelf life and use by dates. Your protein shake may keep longer when stored in a cool, dry place.


Common protein shake mistakes


While it used to be thought that you had to consume your protein shake within 30 minutes after a workout, research now shows that there are benefits of a higher protein intake up to 24 hours after your workout.3

So, consuming your shake shortly before or after your workout still provides your body with those necessary building blocks to help your muscles build and recover. You may change the timing of your shake based on your meals or your daily schedule.

One common mistake to avoid is consuming you shake along with a high protein meal. Our bodies do have a limit to how much protein we can absorb at once, so it’s best to spread your protein out into 3-4 meals or snacks throughout the day.3



While whey is a common type of protein powder, most of the lactose has been removed. However, if you have an allergy to milk or to another type of protein source, it’s best to avoid choosing a supplement made from those ingredients. If you’re not sure about a possible intolerance, start with a small dosage and see how you feel before increasing the amount of the shake you consume.


How much is healthy

The International Society of Sports Nutrition recommends about 0.25 grams of protein per kilogram of body weight per serving of protein, or 20-40 grams in one shake or meal for active athletes.3 Our bodies can’t absorb or use more than this amount at once, so extra would be stored as fat. Daily protein shakes have been shown to be safe in generally healthy adults.4


Protein shakes as meal replacements

Protein shakes can function well as meal replacements as long as they contain the nutrition you would consume at a normal meal – think not just protein, but also carbohydrates and healthy fats. Adding fruit (frozen bananas or berries) or vegetables (like spinach) can increase the volume and add healthy carbs and fibre to your shake.

If your protein shake is low in fat, you can add some peanut butter or avocado to round out your macros. Milk is a simple way to boost the nutrition of your shake and make it more like a meal, while adding healthy calcium and additional protein.

Protein Shake Side Effects

While our kidneys play a role in processing protein, people with healthy kidneys don’t need to worry about a reasonable daily protein intake.4 If you have any health concerns that affect your kidneys, like diabetes, talk with your doctor before taking a protein shake supplement.5 Cysteine and methionine are two amino acids that contain sulphur, which can cause kidney damage in large amounts, so avoid taking extra of these amino acids with your protein shake.5

Take Home Message

While protein shakes have been a go-to for athletes for years, they can also be useful for weight loss and as a meal replacement for people on the go. Not just beneficial for weightlifters, protein shakes can also be a recovery tool for endurance athletes like runners and cyclers. Healthy adults can benefit from adequate protein like that found in protein shakes with few potential side effects. Check the label on your protein shake to choose the best one to meet your goals.


  1. Pasiakos, S. M., McLellan, T. M., & Lieberman, H. R. (2015). The effects of protein supplements on muscle mass, strength, and aerobic and anaerobic power in healthy adults: a systematic review. Sports Medicine45(1), 111-131.
  2. Devries, M. C., & Phillips, S. M. (2015). Supplemental protein in support of muscle mass and health: advantage whey. Journal of food science80(S1), A8-A15.
  3. Campbell, B., Kreider, R. B., Ziegenfuss, T., La Bounty, P., Roberts, M., Burke, D., … & Antonio, J. (2007). International Society of Sports Nutrition position stand: protein and exercise. Journal of the International Society of Sports Nutrition4(1), 8.
  4. Pasiakos, S. M., Austin, K. G., Lieberman, H. R., & Askew, E. W. (2013). Efficacy and safety of protein supplements for US Armed Forces personnel: consensus statement. The Journal of nutrition143(11), 1811S-1814S.
  5. Soenen, S., & Westerterp-Plantenga, M. S. (2008). Proteins and satiety: implications for weight management. Current Opinion in Clinical Nutrition & Metabolic Care11(6), 747-751.

Claire Muszalski

Writer and expert

Claire is a Registered Dietitian through the Academy of Nutrition and Dietetics and a board-certified Health and Wellness Coach through the International Consortium for Health and Wellness Coaching. She has a Bachelor of Science in Biology and a Master’s degree in Clinical Dietetics and Nutrition from the University of Pittsburgh.

Talking and writing about food and fitness is at the heart of Claire’s ethos as she loves to use her experience to help others meet their health and wellness goals.

Claire is also a certified indoor cycling instructor and loves the mental and physical boost she gets from regular runs and yoga classes. When she’s not keeping fit herself, she’s cheering on her hometown’s sports teams in Pittsburgh, or cooking for her family in the kitchen.

Find out more about Claire’s experience here.