What is the Difference Between Whey and Casein Protein?

What is the Difference Between Whey and Casein Protein?

With so many options, it’s challenging to narrow it down when trying to find exactly what you need in a protein supplement. You decide that a grass-fed, milk-based option is right for you, but then another choice pops up: whey protein powder or casein protein powder?

What are the differences between whey protein & casein protein?

Just like whey, micellar casein protein is derived from milk. In fact, casein makes up 80% of milk protein.

Aside from their common source, whey and casein share many similarities, including their ability to aid increases in net muscle protein balance, as well as their effects on body composition and performance. They both also contain all 9 essential amino acids, or the amino acids our bodies cannot make (therefore it is “essential” we get these through what we eat).

Although whey and casein have so much in common, they have some pretty major differences. The biggest?

Absorption rates.

Whey is known as a quick-digesting protein, which is why many athletes consume it directly after a workout for lean muscle repair. Casein, on the other hand, is a larger molecule and digests slowly. In fact, the difference in size may be attributed to their differences in branched chain amino acid levels (whey has a higher percentage than casein). So if whey has more BCAAs and digests faster, why even use casein?

Slow-digesting proteins like casein can be advantageous!

Casein takes a significant amount of time to be absorbed by our body and it has a unique ability to linger and work for longer periods of time. Whey, on the other hand, is quick to act but also quick to leave. Casein can be the perfect protein source for those who need prolonged satiety and recovery. If you often wake up feeling ravenous after a full night’s sleep, casein can be a fantastic option to keep hunger levels steady and make sure your muscles are getting the nutrition they need overnight.

So what exactly are the benefits of casein protein powder?

1. Casein helps to build muscle mass and prevent muscular breakdown, especially while dieting (1)

2. It lasts longer due to its slow absorption (2)

3. It makes for an ideal snack before bedtime, keeping you from waking up hungry (3)

4. Casein keeps you satiated, which helps manage hunger, shed fat, and promote weight loss (4)

When should I use casein protein?

Casein can be taken at similar times to whey protein. It can be taken before a workout, after a workout, or during the day to keep you satiated, yet, casein has also proven to be beneficial before bed due to its slow digestion, allowing your body to absorb protein in your sleep.

Are there foods high in casein?

Yes! As a derivative of milk, casein can be found in dairy products, such as milk, cheese, and yogurt. Small amounts of casein can also be found in other sources, such as tuna and semisweet chocolate.

What is micellar casein and how is it different from hydrolyzed casein (5)?

Micellar casein is the most popular form of casein and is digested slowly, while casein hydrolysate is predigested and is rapidly absorbed. Depending on your goals, one form of protein may be more suitable than the other. For example, if you are looking to gain lean muscle mass, adding micellar casein would be the way to go.

Would I be able to have casein if I have a milk allergy? What if I am lactose intolerant (6)?

A milk allergy is an abnormal immune response to milk and products containing milk. This is different from a milk intolerance because an intolerance does not involve the immune system. Cow’s milk is the most common milk allergy, with casein and whey being the two forms of protein to cause such an abnormal immune response.  

It is best to speak with a healthcare professional regarding any allergy or intolerance concerns. If you have a milk allergy, it is important to determine if the allergic response is triggered by whey or casein.

It is also important to determine if you are milk intolerant. If you are lactose intolerant, it is okay to consume casein, as long as you do not experience any adverse effects. However, it is best to speak with a healthcare professional, as trace amounts may be present.

Why Promix?

Promix Casein Protein Powder is slow-digesting and provides a sustained release of amino acids over time. For this reason, micellar casein is known as “The Before Bed Protein.”

Promix utilizes proprietary, industry-leading filtration techniques, superior sourcing, and 3rd-party quality testing to ensure our customers receive the best casein protein powder on the market. Our product offers the full spectrum of casein proteins – Alpha s2, Beta, and Kappa-casein – and is always free of soy, gluten, GMOs, and synthetic additives of any kind. We offer our casein in unflavored and in chocolate, flavored with Organic Fair Trade Cocoa for a sweet night time snack.

What are the key takeaways?

There are major benefits to BOTH casein and whey proteins: it comes down to your individualized goals and preferences. So if casein is right for you check out Promix Micellar Casein Protein Powder in either unflavored or chocolate made with organic, fair-trade cocoa for a naturally light, sweet bedtime snack. Each variety packs 25-26 grams of protein with <1 gram of fat and <7 grams carbohydrates per serving. Crush your daily protein goals and get the energy you need to rebuild muscle effectively – you deserve a fresh start every single day!

If you have any questions regarding our natural protein supplements and how they support your training, visit our FAQs page, or feel free to email us at sales@promixnutrition.com. Be sure to follow Promix Nutrition on instagram for the most up-to-date announcements and creative recipes that utilize casein.


(1) Demling RH, DeSanti L. Effect of a Hypocaloric Diet, Increased Protein Intake and Resistance Training on Lean Mass Gains and Fat Mass Loss in Overweight Police Officers. ANM. 2000;44(1):21-29.

(2) Mariotti F, Valette M, Lopez C, et al. Casein Compared with Whey Proteins Affects the Organization of Dietary Fat during Digestion and Attenuates the Postprandial Triglyceride Response to a Mixed High-Fat Meal in Healthy, Overweight Men. J Nutr. 2015;145(12):2657-2664.

(3) Snijders T, Res PT, Smeets JS, et al. Protein Ingestion before Sleep Increases Muscle Mass and Strength Gains during Prolonged Resistance-Type Exercise Training in Healthy Young Men. J Nutr. 2015;145(6):1178-1184.

(4) Alfenas R de CG, Bressan J, Paiva AC de. Effects of protein quality on appetite and energy metabolism in normal weight subjects. Arquivos Brasileiros de Endocrinologia &amp; Metabologia. 2010;54(1):45-51.

(5) Mawer R. Why Casein Is One of The Best Proteins You Can Take. Healthline Website. https://www.healthline.com/nutrition/casein-protein-is-highly-underrated. Published September 16, 2016. Accessed August 27, 2018.

(6) Milk allergy – Symptoms and causes – Mayo Clinic. Mayo Clinic Website. https://www.mayoclinic.org/diseases-conditions/milk-allergy/symptoms-causes/syc-20375101. Accessed August 27, 2018.1.

How much protein do you need? Protein Calculator