Two hundred grams of protein a day, sometimes more, for a man weighing roughly 80 kilograms. That was my routine for the better part of two years: chicken breast at breakfast, a shake between meetings, cottage cheese before bed, all in service of a number I’d picked up from a gym forum, 2.5 grams per kilogram of bodyweight. Then I actually read the research the bodybuilding crowd kept quoting, and it turns out the science says something rather different from what got passed around as gospel.
Key takeaways
- A trusted gym rule turned out to be built on misread science—what does the actual research say?
- The sweet spot isn’t where most lifters think it is, and the data shows it plateaus in a way that surprises almost everyone
- Age and training experience shift the goalpost more than most people realize—your number might be very different from your gym buddy’s
The study that moved the goalposts
The paper in question is a 2018 systematic review and meta-analysis published in the British Journal of Sports Medicine, led by Robert Morton and colleagues at McMaster University. The team performed a systematic review, meta-analysis and meta-regression to determine if dietary protein supplementation augments resistance exercise training-induced gains in muscle mass and strength. This wasn’t a single small trial with a handful of eager gym-goers. Data from 49 studies with 1863 participants showed that dietary protein supplementation significantly increased changes in strength, fat-free mass, and muscle fibre cross-sectional area during periods of prolonged resistance exercise training.
Here’s the part that stopped me mid-shake. Protein supplementation beyond total protein intakes of 1.62 g/kg/day resulted in no further resistance-training-induced gains in fat-free mass. The researchers ran a two-phase break point analysis, essentially plotting protein intake against actual measured muscle gain to find the exact point where the curve flattens out. Using segmental linear regression between relative total protein intake and change in fat-free mass measured by dual energy X-ray absorptiometry, they identified a break point of 1.62 grams of protein per kilogram per day, with a 95% confidence interval extending from 1.03 to 2.20. For someone my size, that translates to roughly 130 grams a day at the plateau point, not the 200-plus I’d been forcing down.
Why the extra scoops weren’t doing much
I’d assumed, like most people chasing hypertrophy, that if a bit of protein helps, a lot more must help a lot more. Muscle protein synthesis doesn’t work that way. It responds to a dose, then saturates, rather like topping up a glass that’s already full. The Morton review didn’t just find a ceiling, it found who benefits most from approaching it. The impact of protein supplementation on gains in fat-free mass was reduced with increasing age and was more effective in resistance-trained individuals. In plain terms, if you’re older or newer to lifting, extra protein does even less heavy lifting for you than it does for a seasoned athlete pushing hard in the gym.
What struck me as almost unfair, given how much money and stomach space I’d dedicated to this, is that the type of protein barely registered as a variable in the pooled data. The gains came from having enough, not from a particular shake, powder or timing ritual. Training stimulus, consistently applied, was doing the heavy lifting all along, with protein playing a supporting role once a sufficient threshold was met.
Turning 1.6 grams into an actual meal plan
Working with a range rather than a single magic number is more honest, and more useful. Given the confidence interval stretched up to about 2.2 g/kg, someone deep into a serious hypertrophy programme with years of consistent training probably isn’t wasting effort by sitting nearer the top of that band. Someone newer to resistance training, or over 50, likely plateaus closer to the bottom. For most people reading this in the UK, aiming to build or maintain muscle while training two to four times a week, that means:
- An 70 kg person: roughly 112 to 154 grams of protein daily
- An 80 kg person: roughly 128 to 176 grams daily
- A 90 kg person: roughly 144 to 198 grams daily
Spreading that across three or four meals, rather than trying to cram it into one enormous post-gym shake, tends to be easier on both digestion and the wallet. I’ve since dropped the extra scoop of powder, added a proper portion of fish or lentils to lunch instead, and haven’t noticed a scrap of difference in strength or how my clothes fit. What I have noticed is spending considerably less on supplements I didn’t need.
A number worth remembering
There’s a detail from the same paper that rarely makes it into gym chatter, and it’s more useful than the headline figure. Increasing age reduces and training experience increases the efficacy of protein supplementation during resistance exercise training. So the 1.6 g/kg figure isn’t a fixed law carved into a protein tub, it’s a population average from pooled trials, and your own sweet spot shifts depending on how long you’ve been training and how old you are. If you’re managing a health condition, particularly anything affecting kidney function, or you’re pregnant, breastfeeding, or under 18, these figures don’t apply to you in the same way, and it’s worth having a proper conversation with your GP or a registered dietitian before overhauling your intake. For everyone else, the lesson from Morton’s team isn’t that protein doesn’t matter. It’s that past a fairly modest threshold, the extra grams are mostly just expensive, and rather bland, insurance.
Sources : researchgate.net | pubmed.ncbi.nlm.nih.gov