You’ve heard that taking a protein shake before bed will help you build muscle faster. But you’ve also heard that doing so is a waste of time, and that protein timing is irrelevant. Just hit your macros by the end of the day and you’ll be fine.
Will drinking a protein shake before bed give you more muscle by morning? Or is it all just a ruse to get you to buy fancy protein supplements that you don’t really need?
Here’s a closer look at what the science has to say on the subject of pre-sleep protein, muscle growth and fat loss.
Bedtime Protein for Bigger Muscles?
Before you go to sleep tonight, take a supplement containing a slow-release source of protein, such as casein.
This will “drip feed” amino acids to your muscles throughout the night, helping them recover and grow while you sleep. You’ll wake up with a little more muscle than you had the night before.
That’s what’s supposed to happen anyway.
Although the advice has been doing the rounds in bodybuilding circles for many years, it wasn’t until 2012 that a team of Dutch researchers put the theory to the test.
They found that 40 grams of protein taken 30 minutes before sleep led to an increase in muscle protein synthesis during the night .
In fact, muscle protein synthesis – a key driving force behind muscle growth – was around 20% higher in subjects given the protein supplement compared with a placebo.
How Pre-Sleep Protein Affects Muscle Growth
Men taking part in the study were assigned to either a placebo or a protein group. The protein group consumed a supplement providing 28 grams of protein and 15 grams of carbohydrate each night before they went to sleep. Group two received a placebo containing no calories.
The supplement contained a 50:50 blend of micellar casein and hydrolyzed casein. While micellar casein is digested relatively slowly, hydrolyzed casein has been partially pre-digested, which means it’s absorbed more quickly than regular casein .
The size of the quadriceps, measured using a CAT scan, increased in both groups. But it was the pre-bed protein group that grew the fastest, gaining 75% more muscle than their counterparts in the placebo group.
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Changes in muscle fiber size were also greater in the pre-bed protein group. In fact, the increase in type II muscle fiber size seen in the protein group was more than double that of the placebo group.
In addition, maximal strength across all six exercises increased by 361 pounds (164 kilograms) in the protein group – a 26% increase compared to the placebo group.
At first glance, this study appears to support the use of a protein shake before bed.
However, all research comes with limitations, and this trial is no different. The main problem is that protein intake wasn’t matched between the groups.
The Pre-Sleep Protein Group Ate More Protein
Subjects in the placebo group consumed, on average, 0.6 grams of protein per pound (1.3 grams per kilogram) of bodyweight per day. However, average protein intake in the pre-sleep protein group was roughly 0.9 grams per pound (1.9 grams per kilogram) of bodyweight.
The fact that the bedtime protein group ended up consuming almost 50% more protein than the placebo group does make it a little tricky to interpret the results.
We don’t know if it was the time at which the protein was consumed, or simply the extra protein itself, that generated the extra gains.
Here’s what the researchers themselves have to say on the subject:
“Ingestion of the protein supplement before sleep was not compared with other time points of ingestion. As such, we can only speculate on the surplus benefit(s) of the protein supplement being provided before sleep as opposed to other time points throughout the day.”
The 2012 study had the same weakness – daily protein intake was around 40 grams higher in the group given protein before bedtime.
But that’s not all.
Both groups trained between 8pm and 10pm. Immediately after training, they were given a small meal containing around 10 grams of protein.
This means that the placebo group didn’t have anything further to eat until breakfast the following morning, and went 10-12 hours after training having been given just 10 grams of protein.
Had both groups been given a post-training meal containing 30-40 grams of protein, any muscle-building advantage to the bedtime protein supplement may well have been eliminated.
The results may also have been very different had both groups trained in the morning or afternoon, where there would have been a greater post-training provision of nutrients.
In summary, both studies provide some support for the idea that taking a protein shake before bed will speed up muscle growth. But the fact that protein intake wasn’t matched between groups is a problem.
We don’t know if it was the additional protein, or the time at which it was consumed, that was primarily responsible for the additional gains in size and strength.
Some Studies Show No Benefit to Pre-Sleep Protein
In fact, when daily protein intake is matched, there’s very little evidence to show that taking a protein shake before bed will help you build muscle any faster.
When a team of US researchers put the idea to the test, there was no difference in muscle growth with a protein shake before bed compared to the same amount of protein consumed during the day .
They took a group of recreationally active young men, and assigned them to one of two groups. The men lifted weights four times a week for ten weeks, and took a daily casein supplement providing 35 grams of protein.
The only difference was in the timing of the protein. One group took the supplement during the day, while group two took it shortly before going to bed.
Lean body mass (a reasonable proxy for muscle mass) increased to a similar extent in both groups. Ultrasound scans also show similar gains in muscle thickness. What’s more, there was no significant difference in strength gains on the leg press and bench press between the two groups.
In short, given enough daily protein, a pre-bed casein supplement worked no better for muscle growth than the same amount of casein taken during the day.
Other studies report much the same results.
In one trial, eight weeks of supplementation with two scoops of protein powder (providing 54 grams of casein) consumed 90 minutes or less prior to sleep delivered no additional muscle gains compared to the same amount of protein taken in the morning .
Is a Protein Shake Before Bed Good for Weight Loss?
The idea that taking a protein shake before bed helps with weight loss is based on the finding that pre-sleep protein raises your metabolism the following morning compared to eating nothing [8, 9, 10].
However, this doesn’t mean that taking a protein shake before bed will help you lose fat any faster.
For one, pre-sleep carbohydrate has also been shown to raise metabolism the following morning . It’s not something that’s unique to protein.
What’s more, the finding that pre-sleep protein raises your metabolism doesn’t show up in every study.
In one trial, a casein supplement providing 30 grams of protein had no effect on fat metabolism, metabolic rate, or appetite the following day . In another, a bedtime glass of milk containing 10 or 30 grams of protein failed to increase resting metabolic rate the following morning .
What matters when it comes to losing fat is the amount of fat burned over a period of weeks and months.
By itself, taking a protein shake before bed isn’t “good” or “bad” for weight loss. As long as your overall diet is set up properly (which my Gutless nutrition manual will show you how to do) pre-bed protein isn’t going to have a big impact on your rate of fat loss one way or the other.
Is it worth taking a protein shake before bed? That depends. If you’re already hitting your protein targets for the day, and eating a protein-rich dinner an hour or two before going to sleep, a pre-bed protein shake won’t make much difference to your results one way or the other.
But if your daily protein intake is on the low side, there’s a gap of several hours between eating a protein-rich meal and going to bed, or the protein content of that meal is relatively low, then a pre-sleep protein shake is certainly worth incorporating into your diet.
It’s not going to hurt, and may well have a small but significant impact on your results over time.