What’s the difference between whey and casein protein and when’s best to digest them?

Confused about whey and casein proteins and how they help? Nick Smith explain the difference and when triathletes should take them.

Image By Sandstein [CC BY 3.0 (https://creativecommons.org/licenses/by/3.0)], from Wikimedia Commons https://commons.wikimedia.org/wiki/File:Protein_shake.jpg

A number of foods contain protein in varying amounts with higher concentrations found in meat, fish, milk and eggs, and less in vegetables and fruit. The key is to look for the most complete proteins because these will provide a higher level of muscle recovery.


It can be difficult for triathletes to get enough protein, so you may choose to include additional sources in your diet in the form of protein bars and drinks. These usually include the two types of protein found in milk: casein and whey.

Casein is often referred to as ‘time-released’ protein because it’s digested and absorbed much slower than other proteins.

Whey protein, or ‘fast’ protein, is a rich source of low-fat protein that quickly nourishes muscles.

Whey proteins are a good choice for the morning and just before a workout because they’re quickly digested. But equally, recovery proteins containing whey, casein, egg and simple carbohydrates will help recharge your body after a tough workout.


Dairy proteins (whey and casein) help to control appetite between meals because they stimulate the release of gut hormones that trigger a feeling of fullness. Finally, a casein protein shake 30mins before bed will prepare your body for the fast ahead.

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