Pre-Bedtime Protein Does Not Preserve Muscle Mass, Suggests New Study

Bodybuilders are a ritualistic bunch. For the muscle-minded, weighing food, drinking water from a gallon jug, or chugging a protein shake right before bed are cultural norms.

But a Nov. 2023 study indicates that consuming protein before bedtime — an extremely commonplace habit among bodybuilding enthusiasts — may not help you build muscle (or hold onto it) while you snooze, even if you’re in a calorie deficit.

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Does this finding mean you should stop fixing a whey shake as part of your nightly ritual? Not necessarily, but it might provide some comfort to anyone who thinks they aren’t getting “enough” protein daily.

Editor’s Note: The content on BarBend is meant to be informative in nature, but it should not be taken as medical advice. When starting a new training regimen and/or diet, it is always a good idea to consult with a trusted medical professional. We are not a medical resource. The opinions and articles on this site are not intended for use as diagnosis, prevention, and/or treatment of health problems. They are not substitutes for consulting a qualified medical professional.

What the Study Says

The paper in question was published in the journal Frontiers in Nutrition in late 2023 and is titled, “Pre-sleep protein supplementation does not improve performance, body composition, and recovery in British Army recruits,” by Chapman et al. (1)

The authors’ principal aim during this clinical trial was to, “establish the influence of an isocaloric, moderate (20-gram) and high (60-gram) bolus of protein prior to sleep on performance adaptations, body recomposition, and chronic recovery…” Here’s a more specific rundown:

99 male and 23 female recruits for the British armed forces were assembled for a 12-week study during their basic army training.

Participants were assigned to one of four daily protein intake levels: 1.17g/kg (grams per kilogram of body weight), 1.31g/kg, 1.71g/kg, and 2.16g/kg.

The recruits were assessed on muscular strength via several tests, including the mid-thigh pull, 4-kilogram medicine ball throw, 2-minute push-up test, and vertical jump.

Researchers measured all 122 participants’ body composition (their fat-to-lean-mass ratio) via DXA scanning.

Notably, the study’s participants also had a broad total daily energy expenditure (TDEE) range of 3,400 to 4,900 calories per day. They self-reported their caloric intake to the researchers, which fell in a general range of 2,200 to 2,700 calories per day.


Here’s where things get interesting. These are the main findings outlined by Chapman & colleagues:

Protein supplementation had no impact on any of the performance tests.

Changes in fat-free mass (including but not limited to muscle) were mostly static between groups.

Protein supplementation had “no impact … on any body composition or recovery measurement.”

The authors bottled their findings by stating, “We conclude no benefits of pre-bed protein supplementation to improve performance, body composition, and recovery during basic training.”


To address the elephant in the room, it’s noteworthy that this study was not conducted on bodybuilders or recreational lifting enthusiasts — the data were collected from armed forces recruits. People training for muscle hypertrophy tend to require higher-than-average intakes of dietary protein, (2) even compared against other types of exercise.

Participants also controlled for their own caloric intake. Energy balance is the primary determinant of weight change, and leaving that up to participant self-reporting may muddy results.

This 12-week clinical trial may not have lasted long enough to measure meaningful change in muscle mass, which can often take many months to accrue.

Participants had no notable strength training background to speak of.

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What You Should Do

So, how can you interpret this study and utilize it to your benefit? For starters, you may not need to throw away your casein protein powder just because of one paper’s findings. Other studies (3) indicate that pre-bed protein supplementation positively augments muscle protein synthesis overnight.

Practically speaking, the Chapman study should ease your mind if you’re worried about protein timing. When examining this paper alongside the greater body of protein-related research, it’s becoming clearer that you don’t need to drip-feed your system with regular doses of protein to build muscle.

Our tester mixing a shake of Transparent Labs Organic Vegan

Downing a protein shake — or digging into some cottage cheese, also a bodybuilding meal prep staple — probably won’t help you spare muscle you’d otherwise lose overnight if you were in a strong calorie deficit.

But there’s also no harm in it, either, and spacing your protein intake out over your waking hours is generally more palatable than trying to get it all in one or two sittings.

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Chapman, S., Roberts, J., Roberts, A. J., Ogden, H., Izard, R., Smith, L., Chichger, H., Struszczak, L., & Rawcliffe, A. J. (2023). Pre-sleep protein supplementation does not improve performance, body composition, and recovery in British Army recruits (part 1). Frontiers in nutrition10, 1262044.

Morton, R. W., Murphy, K. T., McKellar, S. R., Schoenfeld, B. J., Henselmans, M., Helms, E., Aragon, A. A., Devries, M. C., Banfield, L., Krieger, J. W., & Phillips, S. M. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British journal of sports medicine52(6), 376–384.

Trommelen J, van Loon LJ. Pre-Sleep Protein Ingestion to Improve the Skeletal Muscle Adaptive Response to Exercise Training. Nutrients. 2016 Nov 28;8(12):763. doi: 10.3390/nu8120763. PMID: 27916799; PMCID: PMC5188418.

Featured Image: Kmpzzz / Shutterstock

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