Casein vs Whey Protein

The casein vs whey protein debate has raged on for years but the common perceptions that whey is a “fast” protein and casein is “slow” are actually incorrect.

In this article we look at the scientific studies to establish exactly which protein source is better for dieters concerned with building muscle and losing fat.

Before we get into the specifics about these two protein sources, it’s important everyone is clear of the difference between the two types of protein powders.

Ever opened a yogurt or cream cheese and noticed the milky, thin liquid sitting on top? Well that’s whey protein and ironically that was the bit I used to pour down the sink!

casein vs whey

That thin liquid is a by-product of cheese production and when it is concentrated and dried you get whey protein powder.

The common perception about whey protein is that it is recommended for the post workout “window of opportunity” due to its fast digestion and absorption into your blood stream.

Casein protein on the other hand is known as a slow protein that takes longer to digest; it is also naturally found in dairy products such as cottage cheese.

If you’ve read much of my site you’ll know that common perceptions are usually wrong. So often that you’d think I was just making it up to be controversial but I’m afraid not. Most of the widely accepted nutritional guidelines are plainly wrong!

Let’s see how the casein vs whey perceptions hold up against laboratory scrutiny!

Casein vs Whey – The Scientific Studies

The most famous study on the effects of casein vs whey was conducted by Yves Boirie in 1997 and used healthy subjects with normal protein intakes.

Titled
“Slow and fast dietary proteins differently modulate postprandial protein accretion”
this study model had participants fast for 10 hours before being given 30g of whey or 30g of casein protein.

The participants blood leucine levels peaked one hour after the whey or casein was ingested.

What is Leucine?

Leucine is an essential amino acid which means your body can’t produce it itself and therefore it must be provided via protein consumption.

It is the only dietary protein that can stimulate muscle protein synthesis (e.g. build new muscle fibres) and it also prevents protein breakdown (muscle loss).

Remember that for muscle gain to occur your protein synthesis must be higher than protein degradation to ensure a positive protein balance. Simply, excess protein makes new muscle.

The same amount of leucine was in both the whey and casein meals fed to the subjects, but the way their bodies reacted to the proteins was very different.

Casein vs Whey: Protein Synthesis

Leucine levels peaked one hour after the both feedings; however, the whey protein group’s leucine levels peaked higher and then returned to normal in four hours.

The casein group showed a lower leucine level but they didn’t return to normal levels until around seven hours later.What does this mean?

This dispels the myth that whey protein gets into your system faster than casein!

In reality whey digests quicker as leucine levels return to normal after four hours compared to casein’s seven.

Note that both leucine levels peaked one hour after feeding – e.g. both protein sources took one hour to have an effect on leucine.

The difference between casein vs whey was that whey spiked leucine levels higher but only for a short period. Casein on the other hand registered a lower leucine level but it was elevated for a longer period.

This indicates that both casein and whey have unique benefits, let’s play protein top trumps to make things clearer:

Casein vs Whey: Facts at a Glance

Whey Protein
Entered System: After 1 hour
Protein Synthesis Increase: 68%
Protein Breakdown Decrease: None
Leucine Levels Returned To Normal: After 4 hours

Casein Protein
Protein Synthesis Increase: None
Protein Breakdown Decrease: 34%
Leucine Levels Returned To Normal: After 7 hours

In summary, although leucine levels were higher in the whey group, the overall leucine concentration was elevated for a longer period on the casein group. Therefore, the protein balance was positive for a longer time in the casein group and the body stored more leucine than in the whey group.

Phrased a bit differently, it looks as if decreasing protein breakdown was more important than increasing protein synthesis in terms of whole body leucine (and therefore, protein balance).

Casein vs Whey – Final Thoughts

The purpose of this article isn’t to choose a winner as in reality both types of protein have unique properties that can be useful for dieters.

Let’s look at the benefits of casein vs whey in order to establish when one protein source is superior to the other:

Pre-Workout Protein
Before a workout you want to consume protein and carbohydrates in order to fuel your workout and to ensure your body has the nutrients it needs to grow following your workout. In instances like this a whole food meal 90-120 minutes before your workout is probably best.

I sometimes struggle to get a meal in before the gym as I train after-work most days, therefore I use a protein shake to get a quick protein fix that’s digested quickly.

In situations like this I need a protein powder that digests quickly and one that won’t sit in my stomach while I’m working out as it is hard to push yourself 100% when you’re worried about seeing your pre-workout protein again!

For this reason, I opt for a whey protein shake such as
True Whey
by Myprotein.com as it fits the bill perfectly and wouldn’t sit in my stomach like a casein protein shake would (as casein takes 7 hours + to digest).

Post Workout Protein
Both proteins entered the system after one hour, however, whey protein was the only one that increased protein synthesis (+68%). During the post-workout period you need to increase protein synthesis in order to repair the damaged muscle fibres and rebuild them. Clearly whey is the optimal choice in this respect.

With that said there are newer studies that show that a whey/casein blend could be a better choice as they have demonstrated higher levels of protein synthesis and reduced levels of protein breakdown.

Overnight/Between Meals Protein
Diets often use protein shakes between meals for convenience, I always keep a shaker handy if I think I’m not going to be able to get a meal in due to my schedule.

During really busy days I might not be able to eat for 7-8 hours so I need a ways of keeping myself full up and preventing muscle loss which could occur if I waited too long to eat some protein.

In this scenario, casein protein is clearly superior as it would be before bed when you won’t be eating again for 6-10 hours.

In Summary
If you can only afford one protein powder and it really is a choice between casein vs whey my personal preference would be a whey/casein blend as it is the best of both worlds.

However, if you can afford it I recommend purchasing a whey protein product as well as a whey/casein blend as it makes the all important pre-workout protein feeding quick and easy and the price is far outweighed by the convenience it provides.

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