Hello and welcome to The Ideal Nutrition Podcast. This is episode 70, and I am your host, Leah Higl, and I am here with my co-host, Aidan Muir, and today we’re going to be answering the question, should you have slow absorbing protein before bed?
Now, my first run-in with this question was definitely when I was a teenager, and I bought a huge tub of casein off some website after I read it on bodybuilding.com or like Simplyshredded or something like that. And I was super pedantic about having my whey protein isolate directly after training and my casein directly before bed. I used to think it was like the be-all and end-all. So I’m sure a lot of people kind of have this question, especially the ones that kind of grew up learning about that and casein, probably have the same question and want it answered. So we’re going to go through that today.
I’d forgotten this, but I remember, I first got into lifting when I was 17 years old. My parents were very anti-supplement. I bought whey protein and hid it from my parents, and when my dad found it, he got really mad at me. But I wasn’t game to buy casein as well, but I’d heard cottage cheese was a good source of casein protein. So I’d eat cottage cheese before bed by itself.
Yes, I did the same thing when I couldn’t afford to buy casein powder. I’d just eat cottage cheese before bed.
Yeah. Classic. That’s funny. But the basic simplified theory is that whey protein is fast acting and casein and protein is slow acting. So theoretically, obviously whey protein should be perfect post-workout when you want quick acting protein, because you are really sensitized to muscle protein synthesis directly post-workout, is the kind of theory. We’ve kind of touched on that multiple times with this whole anabolic window kind of thing, but we’ll talk about that a little bit more today as well. But the casein aspect of it is theoretically you’re about to go to bed, fast for eight plus hours, I hope, some people it might be less, fast for a decent period of time, and therefore it could make sense based on that logic to have a slow release type of protein so that you’re not in a catabolic state for eight plus hours, is the idea. And that you have something to kind of offset that catabolism, which is the process of breaking down muscle because you’d have this protein in there to help you be building muscle ideally, is the logic.
In regards to the research, casein before bed typically shows improvements in muscle gain. So there was a 2020 systematic review that found 40 to 48 grams of casein 30 minutes before bed showed improvements overall in muscle growth and strength gains. But, and there’s always a “but” when it comes to this stuff, there is quite a bit to note about interpreting this kind of research.
Yeah. So I wrote a blog post on this relatively recently, and given that I’ve been around the evidence-based space for a while, and there is the obvious question, “Why isn’t everybody in the evidence-based space having casein protein directly before bed if the research is this clear?” It was really interesting when I was writing this blog post, going through the research once again, if you look at every study individually, it looks really positive. If you look at that systematic review, it looks really positive. There’s only good things that are happening by this, but there’s a lot of things to unpack, which is kind of the explanation as to why most people in the evidence-based space aren’t actually doing this.
The first one is the differences in the rates of digestion and absorption of whey in casein actually mostly disappear when you add pretty much anything to them. If you add milk to them, if you add anything else to them, these differences in rates of digestion and absorption pretty much disappear as measured by the increase in muscle protein synthesis and how quickly that happens. And that is just because in the context of a mixed meal, adding anything to it slows down the rate of digestion because there’s more things to digest, which is also an interesting thing.
I remember we were talking about this, but I couldn’t find many easy charts that actually measured the rate of digestion of any of these proteins. There’s a lot of talk being like, “Whey is quick and casein is slow,” but one of the first things I wanted to identify is this like, “Well, what context are we looking at?” Like, if whey is X quick, for example, and casein is X minus two, like a small difference or something like that, does this actually matter? Is it a big, big difference? And a lot of charts just have it laid out like, “Whey is quick. And then soy is like medium,” and then a few other ones are in the medium kind of thing. And then casein is slow. And then there was one thing that actually measured the rate of digestion and absorption, and it had just casein in the middle, just like as a real curve ball and amongst it.
And that was the only thing that I actually saw that really measured the rate of digestion absorption, but everyone else has this other consensus. So I’m inclined to look at the other consensus and think like, “It actually is the case that whey is quick, casein is slow,” but I think it’s just a really interesting question to ask and be like, “We don’t really have very easily accessible rates to digestion and absorption.” But anyway, none of that matters, because as I said, the differences in rate of digestion and absorption disappear when you add other stuff anyway. So if you’re not just having it just with water, that’s something that’s worthwhile being aware of.
The next thing to factor in when interpreting the research, is having pretty much any form of protein before bed seems to increase muscle growth in pretty much all the studies that have done it. It doesn’t matter whether it’s casein, that systematic review that was mentioned, they looked at casein before bed, but they weren’t comparing casein before bed to other options, they were just looking at casein before bed.
Another thing that’s not directly on this, should you have protein before bed topic, but it is that whey versus casein kind of concept, is the whole theory of whey post-workout and casein before bed is a little bit undermined by the fact that research shows that if you have casein post-workout versus whey post-workout, the results come out the same in terms of muscle growth. That has been studies, the studies have been done. The results in terms of muscle protein synthesis is different. Muscle protein synthesis spikes a little bit higher with whey protein and then dips quicker, whereas with casein it’s a slower kind of… It stays around for longer. I have seen those rates of digestion absorption in terms of muscle protein synthesis, but what we care about is muscle growth.
Yeah. Practically we care about the gains you’re making.
Yeah. And the research on that topic has shown that they come out the same. So it’s like, “Well, if it undermines that part of the hypothesis, how much does the other part really matter?” And let’s look at it. Taking one step back from all of this, if the reason that casein is beneficial before bed is because of its slower rate of digestion, and we know that the rates of digestion absorption disappear when you add anything else, couldn’t you add any other protein source or any mixed meal or anything like that and get the same benefit? Couldn’t you have whey protein mixed in with milk and a few other things or something like that and get the exact same results based on that logic?
Yeah. And what if you’re just having dinner where you’re having just any kind of protein source?
With some fats to slow digestion and fiber and stuff, isn’t that going to be quite similar?
Yeah, exactly. And that’s the conclusion that I’ve come to and based on the evidence-based industry, not having casein before bed on average, some do obviously, but not everyone does. I think that’s the conclusion everyone else has come to as well.
Yeah. I think casein before bed, it’s another one of those broscience facts that does no harm.
So it’s okay if you want to have casein before bed, that is cool, and especially if it helps you meet your total protein intake which we know is the most important, more so than timing and things like that. So go for it if you want to, but it doesn’t seem to make a huge difference practically to muscle growth outcomes and strength outcomes. Having protein before bed though, probably slightly beneficial in terms of like it’s just part of spreading it out over across the day. Like if you’re having it couple of hours before bed, rather than stopping at six hours before bed, I know there might be some benefit there that you might get, but overall, how much protein you’re consuming is going to matter way more than any of this stuff.
Yeah. And we know you don’t need to take that spreading it out concept to an extreme. There’s been quite a bit of research just showing that you don’t need to have it the second you wake up and the second you’re about to go to sleep. I’m aware of, I won’t give him the shout out, but one of my friends, he’s in the body building space and he is on Instagram and stuff like that, he used to get up in the middle of the night to have whey protein so he wouldn’t be catabolic for too long. And he’s jacked, he’s full, full jacked, but a few years ago he was full broscience. And he knew the evidence and stuff like that, but he was like, “I don’t know. I’ve seen other jacked body builders do this. I’m going to listen to them.”
And he would set an alarm for it. I don’t know. I’m like, “I know sleep matters a lot though”
Well, I don’t know. If it cuts into your sleep, that’s when I’m like, “It’s probably actually being, becoming maybe detrimental at that point.” But whilst it’s not necessary to have protein from the moment you wake up to the moment you go to bed, if you do, you’re probably not doing yourself any harm.
That’s another point. Yeah. And on that topic as well, some people will be concerned about sleep quality, being like, “Well, if I have a lot of food before I go to bed?” We talked about it in the last thing. If you go to bed feeling overly full, it’s likely to disrupt your sleep quality, but this is likely not an issue, because if you do keep it to a small-ish amount like that 20 to 40 gram of protein amount, and it’s at least 30 minutes before bed, it’s unlikely to be an issue in terms of disrupting your sleep or anything.
This has been episode 70 of The Ideal Nutrition Podcast. Thank you to everybody who has listened.