Episode 70 – Should You Have Slow Absorbing Protein Before Bed?

Key Topics Covered

Basic Simplified Theory – Whey vs Casein: 

  • Whey is fast acting, casein is slow acting 
  • Theoretically casein should be good before bed because you are about to fast for 8+ hours.  

What does the research show? 

  • Casein before bed typically shows improvements in muscle gain 
  • A 2020 systematic review found that 40-48g of casein 30 minutes before bed showed improvements in muscle growth and strength gains
  • BUT there is quite a bit to note about interpreting this kind of research and its practical implications – Aidan to lead into below  

Interpreting that research

  • The differences in the rate of digestion/absorption mostly disappear when you add pretty much anything, even milk, to whey or casein.  
  • Protein before bed in general also shows improvements in muscle gain – even if it is not casein 
  • Research comparing whey vs casein around training showed no difference in outcomes. This kind of undermines the whole “whey post workout” part of the hypothesis. 
  • If the reason casein is beneficial before bed is because of the slower rate of digestion, couldn’t you just have almost any other protein source as part of a mixed meal? 

Practical Interpretation 

  • Spreading protein intake out across the day is always a good idea regardless 
  • Protein within a few hours before bed, whether it is casein or another option can help muscle growth. But you likely do not need to take this concept to an extreme e.g. having whey the moment you wake up and casein right before bed. 
  • People who do intermittent fasting with sufficient protein seem to retain muscle quite well, which shows that this idea is not a top priority. 
  • Some people are concerned that eating before bed might disrupt sleep quality. If it is kept to a small amount e.g. 20-40g of protein and is at least 30 minutes before bed, this is unlikely to be an issue.  

Relevant Links/ Resources

Studies Mentioned:

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