The short answer: either works, so choose the time that suits your stomach and your day. In a 10-week trial, a 25g shake before lifting and the same shake after gave similar muscle and strength results. A review of 23 studies found total daily protein mattered most. If you train on an empty stomach, have it soon after.
The clock matters far less than gym talk suggests. What moves the needle is how much protein you get across the whole day, and whether you keep lifting.
Is it better to drink a protein shake before or after a workout?
Neither has won so far. The most direct test came from Brad Schoenfeld and colleagues in 2017. They split 21 experienced lifters into two groups. One group had 25g of protein right before training, and the other had the same drink right after. Everyone followed the same full-body program 3 times a week for 10 weeks.
The two groups ended up with similar strength, muscle size and body composition. The study was small and only included trained men, so it can’t settle the question for everyone. Still, it tested the exact question you’re asking.
What do the meta-analyses say about protein timing?
Meta-analyses pool many trials, which makes them better at spotting a real effect. Here are three of the most useful.
| Review | What it covered | What it found |
|---|---|---|
| Schoenfeld 2013 | 23 studies of muscle growth, comparing protein within 1 hour of lifting with protein kept at least 2 hours away | A small edge for timing disappeared after adjusting for other factors. Total protein was the strongest predictor of muscle growth. |
| Morton 2018 | 49 studies, 1,863 people lifting for at least 6 weeks | Extra protein added an average 0.30kg of lean mass and 2.49kg to one-rep max strength. Going past about 1.6g per kg a day added no more lean mass. |
| Wirth 2020 | 65 studies, 2,907 healthy adults | Extra protein added 0.62kg of lean mass in adults and 0.46kg in older adults. No specific timing did better. |
The 2013 review holds the most interesting detail. In studies where total protein wasn’t matched, the people given timed protein averaged 1.66g per kg a day, against 1.33g for the comparison groups. Their shake simply meant they ate more protein. That extra protein, more than the timing, most likely explains the gains.
There’s one honest caveat. Only 3 studies in that review matched total protein properly, so the authors said firm conclusions were hard to draw. Timing could still have a small effect that nobody has measured well. It just isn’t the big deal it was once made out to be.
How long after a workout should you drink a protein shake?
You have hours, as long as you ate beforehand. The famous "anabolic window" rests largely on people training after an overnight fast. In that case, the reviewers say it makes sense to get protein in soon after you finish.
If you ate a meal 1 to 2 hours before training, that food can still be digesting during your workout and into your recovery. A 2013 review suggests keeping your before and after meals within about 3 to 4 hours of each other, or 5 to 6 hours if the first was a large mixed meal.
The International Society of Sports Nutrition says the benefit of exercise for muscle lasts at least 24 hours, though it probably fades with time. So a late shake still counts. You also don’t need to rush out of the locker room.
How much protein should be in your shake?
For most people, 20g to 40g is the useful range. The Society’s general advice is 0.25g per kg of body weight, or 20g to 40g per serving, spread every 3 to 4 hours. A 2018 review aimed at people trying to build muscle went higher: 0.4g per kg at 4 or more meals, to reach at least 1.6g per kg a day.
| Body weight | Per serving, general (0.25g/kg) | Per meal, building muscle (0.4g/kg) | Daily, building muscle (1.6g/kg) |
|---|---|---|---|
| 130lb / 59kg | 15g | 24g | 94g |
| 154lb / 70kg | 18g | 28g | 112g |
| 180lb / 82kg | 20g | 33g | 131g |
| 220lb / 100kg | 25g | 40g | 160g |
Those daily numbers are for active people chasing muscle. Our guide to how much protein you need covers the everyday targets, and that’s the place to start if you’re not lifting yet.
Check your scoop, too. Harvard Health says powders range from 10g to 30g of protein per scoop, so one scoop may fall short. You may have heard your body can only use 30g at a time. A 2023 lab study challenged that, finding 100g after exercise produced a bigger and longer response than 25g. You don’t need 100g, but a large dinner is unlikely to go to waste.
Age shifts this slightly. Research suggests older men need more protein per meal for the same muscle response, and Morton found the added lean mass from supplements shrank with age. If that’s your concern, read how to keep muscle as you age.
When should you drink a protein shake? What to do in your situation
| Your situation | What to do |
|---|---|
| You train first thing, with nothing eaten | Have a shake or a protein-rich breakfast soon after you finish |
| You ate a meal 1 to 2 hours before | No rush. Have your next protein within 3 to 4 hours of that meal |
| Shakes upset your stomach before exercise | Have it after. The Society says timing is largely about what you tolerate |
| You train in the evening | Make dinner your protein meal, or have a shake if dinner is hours away |
| You already hit your daily protein with food | Skip it. A shake is optional |
| Your workout is mostly cardio | Put carbohydrate first if you train long and hard. Protein may help with muscle damage |
| It’s a rest day | Keep your usual daily protein, spread across your meals |
If your usual training is HIIT or you’re just starting strength training, the same logic applies. Consistent training comes first, and a steady protein habit supports it.
Do you need a protein shake at all?
Probably not, if you eat enough protein. Harvard Health gives these food examples: an egg has 6g, 6 ounces of plain Greek yogurt has 18g, and a cup of milk has 8g. A high-protein breakfast often does the job of a shake.
Shakes do have a place when you’re busy, have a small appetite or struggle to reach your number. Before you buy one, try these steps:
- Read the sugar line. Harvard reports some powders carry as much as 23g of added sugar a scoop.
- Check the protein source. Milk-based powders can upset your stomach if you have trouble with lactose or a dairy allergy.
- Look up the brand. Protein powders are supplements, and the FDA leaves safety and labeling checks to the makers. A 2025 Clean Label Project report screened 134 products and found heavy metals, BPA or other contaminants in many, though not all at raised levels. The results are on its website.
- Count the whole drink. Harvard warns some mixes can turn a glass of milk into a drink of more than 1,200 calories.
Talk to your doctor or dietitian first if you have kidney disease. The NIDDK says people with chronic kidney disease may need to adjust how much protein they eat, and your needs can change over time.
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Quick questions
How long after a workout should I drink a protein shake?
Within a few hours is fine if you ate beforehand. A 2013 review suggests keeping your before and after meals about 3 to 4 hours apart. If you trained on an empty stomach, have protein soon after you finish, since the case for speed is strongest then.
Should I drink protein shakes on rest days?
Yes, if you need one to reach your daily protein. Muscle keeps responding to exercise for at least 24 hours, according to the International Society of Sports Nutrition, and reviews point to total daily protein as the main factor. Spread your protein across meals as usual.
Can I drink a protein shake before bed?
You can, but it’s optional. The International Society of Sports Nutrition says 30g to 40g of casein before sleep raises overnight muscle protein building. Later trials in army recruits and professional cyclists found no extra performance or recovery benefit, so meet your daily total first.
Should I drink protein shakes if I don’t work out?
Most people who don’t work out don’t need one. Harvard Health says most of us can get plenty of protein from ordinary food, and it advises whole foods first. A shake can help if your appetite is poor, but ask your doctor if you’re eating very little.
Do protein shakes make you bloated?
They can. Harvard Health says milk-based powders may cause stomach discomfort if you have a dairy allergy or trouble digesting lactose. If that sounds like you, ask your doctor or dietitian, or get your protein from food instead.
Are protein shakes bad for your kidneys?
In healthy, exercising people, the International Society of Sports Nutrition found no controlled evidence that higher protein intake causes harm. Kidney disease is different. The NIDDK says people with chronic kidney disease may need to adjust protein, so check with your care team before using shakes.
This article is general information, not medical advice. If you have kidney disease, a milk allergy or another health condition, or you’re pregnant, talk with your doctor or dietitian before using protein supplements.
Sources
- Schoenfeld BJ et al. Pre- versus post-exercise protein intake has similar effects on muscular adaptations. PeerJ, 2017
- Schoenfeld BJ et al. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr, 2013
- Morton RW et al. Effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med, 2018
- Wirth J et al. The role of protein intake and its timing on body composition and muscle function in healthy adults. J Nutr, 2020
- Aragon AA, Schoenfeld BJ. Nutrient timing revisited: is there a post-exercise anabolic window? J Int Soc Sports Nutr, 2013
- Jäger R et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr, 2017
- Schoenfeld BJ, Aragon AA. How much protein can the body use in a single meal for muscle-building? J Int Soc Sports Nutr, 2018
- Trommelen J et al. The anabolic response to protein ingestion during recovery from exercise has no upper limit in magnitude and duration in vivo in humans. Cell Rep Med, 2023
- Moore DR et al. Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men. J Gerontol A Biol Sci Med Sci, 2015
- Chapman S et al. Pre-sleep protein supplementation does not improve performance, body composition, and recovery in British Army recruits (part 1). Front Nutr, 2023
- Valenzuela PL et al. Pre-sleep protein supplementation in professional cyclists during a training camp. J Int Soc Sports Nutr, 2023
- Harvard Health: The hidden dangers of protein powders
- NIDDK: Healthy eating for adults with chronic kidney disease