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Protein Timing and Digestion Rates

Taking the right type of protein at the right time will certainly help those who are looking to maximize potential lean muscle gained from weightlifting. But how long does protein last in the human body? And more importantly, when are the most crucial times to take in protein?

Protein Digestion Time

How long does protein last or take to digest?

Whey and Casein

In 1997 there was a study done in France that compared blood amino acids levels between whey and casein protein; this was one of the first studies to compare blood amino acids levels with one of the most important variables: time.[1]
What they found really helped to see the main difference between these all important proteins.

      Whey vs Casein Digestion Time     


From this study it is apparent that whey protein spikes blood amino acid levels at a much greater level than casein, but it also drops back down to baseline levels at around the 4 hour mark, which is very fast in comparison to other types of proteins.

Main point: Based on this study it takes whey protein about an hour to hit the blood stream with a total digestion time of around 4 hours.

When to take whey

Since whey protein spikes amino acids levels much higher than casein, it is ideal to consume whey right after a hard intensive workout when the body is looking to use amino acids in the blood stream to repair damaged and worn out muscle.

For the best whey protein powders see: Best Whey.


Casein is shown to max out around the same time that whey does, but it does not spike blood amino acid levels as high, instead it keeps the levels at a mid-range for a significantly longer period of time, up to 8 hours! It is important to note that this study shows that casein maxes out its potential around the same time that whey does, the reason this is important is that many people believe casein takes much longer to hit the blood stream, which is proven to be untrue according to this study.

Main point: Based on this study it is clear that casein takes about an hour to initially hit the blood stream and can take up to 8 hours to fully digest and return blood amino acid levels back down to baseline.

When to take Casein

Since casein supplies a steady amount of amino acids into your blood stream for such a long period; casein is perfect for right before bed or for other times that it just isn't possible to get a meal in for a long time.

For the best casein protein powders see: Best Casein.


1. Boirie Y, Dangin M, Gachon P, Vasson MP, Maubois JL, Beaufrère B. “Slow and fast dietary proteins differently modulate postprandial protein accretion.”,, Clermont-Ferrand, 23 Dec. 1997. Retrieved on 12 Feb. 2016.