Drinking a protein (casein) shake before tucking in for the night increases gains in muscle mass and strength in response to resistance exercise. But so far, it’s not known whether this effect is due to an increased total daily protein intake, or if consuming some of that protein at bedtime makes the difference.
According to a new review of studies conducted at Maastricht University, overnight sleep provides a unique nutritional window for boosting muscle gains.
A number of one-night studies have shown that pre-sleep protein intake increases muscle protein synthesis during overnight sleep in young adults. These findings have led to the idea that over a longer period, a pre-sleep protein supplement can maximize the strength and muscle mass gains during regular resistance exercise training.
In a 2015 study, a research team from Maastricht University put 44 healthy young men on a 12-week weight lifting program. Half were given a nightly pre-sleep protein shake with about 30 grams of casein and 15 grams of carbs, while the other half got a calorie-free drink.
The training was effective: both groups ended with a bigger squat (one rep max) and bigger quads -- but the protein-before-bed group gained significantly more muscle strength and size.
What matters: total protein intake? Or when you consume it?
Are muscle gains boosted by pre-sleep protein, or just a daily higher intake of protein and calories?
Only one study has attempted to answer this question, unsuccessfully, perhaps because there were only 26 participants.
Even so, there are already many indicators that pre-sleep protein specifically is beneficial for healthy young strength trainers.
Fundamentally, pre-sleep protein can be used to improve protein intake distribution over the day.
Muscles can only grow and repair themselves when the right building blocks -- amino acids from protein -- are available in the bloodstream. Unlike blood glucose, the body doesn't store and release amino acids to maintain near-constant circulating levels.
The muscle-building effects of protein supplementation at each meal seem to be additive. In one study researchers found that consuming ample amounts of protein (60 g of whey) before overnight sleep didn't alter the muscle protein synthetic response to a high-protein breakfast the following morning.
Other studies have shown that adding a protein supplement at bedtime doesn't affect appetite the following morning, so it’s unlikely to reduce total protein or calorie intake.
Bedtime protein won't make you fat or interrupt sleep
Study findings suggest that pre-bed protein consumption, especially casein, doesn't cause an increase in body fat. In fact, it appears to actually increase fat metabolism.
It has also been consistently shown that pre-sleep protein ingestion has no effect on sleep onset latency or sleep quality.
While there isn’t conclusive evidence for drinking a casein protein shake before bed to enhance muscle building, the researchers say it still may be worth a try if your fitness goals include increasing muscle.
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