Whey
The most popular protein shake type, whey, is derived from milk. It's digested and absorbed relatively quickly, making it useful for post-exercise recovery. It also has a higher concentration of essential amino acids than whole milk, which may help minimise muscle protein breakdown immediately after exercise.

Casein
Casein, which makes up 80 per cent of the protein content of milk, is made up of larger protein molecules, which are digested more slowly than whey, providing a slow, steady release of amino acids into the bloodstream. This slow release is what many experts argue makes it the best protein to use before going to sleep at night or for breakfast.

Which should you use after a workout?
Many people forget that they can mix their whey with casein (milk). After a workout, a cup of milk [250ml] with a 25g scoop of protein powder equates to a big chunk of fast-acting whey right when you need it, with the added benefit of 16g of long-acting casein.

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