Your Clients Obsess Over Protein Timing. Here's What Actually Moves the Needle.

How we sourced this. Every claim below is tied to a named study — a position stand, a dose-response meta-analysis, a randomised trial, or the live trial registry — and linked. We also graded the evidence: where it’s strong, we say so; where it’s early or contested, we say that too. This piece was reviewed for accuracy before publishing and carries a real byline, because on health topics a citation you can’t stand behind is worse than no citation at all. Last updated 9 October 2026.

The thing your clients overthink the most

No supplement generates more fuss-per-gram than protein. Clients track their post-workout window to the minute, argue about whey versus casein, and buy the fancy blend — while quietly missing their daily total by 40 grams. The energy is pointed at the decimal places and away from the number that actually matters.

So we did the boring, valuable thing: pulled the dose-response meta-analyses, the ISSN position stand, and the timing trials, graded them, and checked the registry for what’s still unsettled. Here’s what actually moves the needle — written so you can use it with a client today, not so you can pass a nutrition exam.

One framing up front: protein is the rare area where the science is genuinely settled on the big question and genuinely nuanced on the small ones. Your job as a coach is to get the big question right first, and only then spend attention on the details that earn it.

The only number that really matters: your daily total

If a client gets one thing right, make it this. Across the controlled evidence, total daily protein is the strongest predictor of how much muscle and strength someone builds. The International Society of Sports Nutrition puts the effective range at 1.4–2.0 g/kg/day for building and maintaining muscle, with higher intakes useful mainly for holding onto lean mass in a deficit.¹ A 74-trial meta-analysis found that eating more protein produced a small but real bump in lean body mass in people who lift (SMD 0.22), and pinned the thresholds where it starts to matter: about ≥1.6 g/kg for under-65s and ≥1.2 g/kg for older adults.³

There’s a ceiling, and knowing it saves your clients money. A dose-response meta-analysis of 82 trials found strength climbed by about 0.72% for every extra 0.1 g/kg/day — but only up to roughly 1.5 g/kg/day, after which more protein bought no further gains.² So the honest target is “enough,” not “as much as possible”: land somewhere in the 1.6–2.2 g/kg band and you’ve captured essentially all of the benefit.

Two more meta-analyses put numbers on that plateau from different angles. Across 49 trials and 1,863 people, adding protein on top of resistance training added about 0.3 kg of fat-free mass and 2.5 kg to a one-rep max — and the break-point analysis found no further lean-mass gain once total intake passed 1.62 g/kg/day. The effect was bigger in trained lifters and shrank with age.⁹ The largest dose-response analysis to date (105 trials, 5,402 people) found lean mass rose about 0.39 kg for every extra 0.1 g/kg/day below 1.3 g/kg/day, but only 0.12 kg per step above it — returns don’t hit zero, they shrink by two-thirds.¹⁰ Same shape, three datasets.

Evidence grade: strong. Multiple large meta-analyses, consistent direction, a clear dose-response with a plateau.

Protein without training doesn’t build strength

This is the caveat that reframes the whole conversation. In that same dose-response meta-analysis, extra protein augmented strength only when it was paired with resistance training — with no meaningful strength gain from protein alone.² Protein isn’t a strength supplement; it’s the raw material that lets training turn into adaptation.

That’s a useful thing to say to a client who’s drinking three shakes a day and wondering why nothing’s happening. The shake doesn’t build the muscle. The training does — and the protein makes sure the build isn’t rate-limited by a lack of material.

Evidence grade: strong. The training requirement is one of the most consistent findings in the literature.

The anabolic window is mostly a myth — for most of your clients

Here’s the belief that drives the most wasted effort, so be precise. The “anabolic window” — the idea that you must slam protein within 30–60 minutes of training or lose the gains — does not hold up once you control for how much protein someone eats overall. A meta-regression of timing studies found that after accounting for total daily protein, timing showed no independent effect on either strength or hypertrophy; total intake was the strongest predictor.⁴

Newer work agrees. An 8-week trial in trained men compared taking protein immediately around training versus three hours away from it, at a matched 2 g/kg/day, and found no difference in muscle mass, strength or performance between the two.⁶ The anabolic response to a training session lasts a day, not a half hour. And the response to a meal is bigger and longer than the old “you can only use 20–30 g” rule claimed: in a tracer study that fed 100 g versus 25 g of protein after a session, the larger dose produced a greater anabolic response that was still running at 12 hours, with no extra amino-acid oxidation — in the authors’ words, no upper limit in magnitude or duration.¹² A big dinner’s protein isn’t wasted; it just works for longer.

So retire “you missed your window.” It invents a failure where none exists and distracts from the thing that does matter — the daily total. For the general client, protein timing is a rounding error.

Evidence grade: strong that timing is secondary to total intake for typical trainees. Frame the window as flexibility, not a deadline.

Where timing genuinely matters: your older clients

Now the honest exception, because a good coach knows when the rule flips. In people with anabolic resistance — most obviously older adults — when you eat protein starts to matter. A classic trial in elderly men had both groups do the same 12 weeks of resistance training and take the same protein, but one group took it immediately after training and the other two hours later. Only the immediate group gained muscle cross-sectional area; the delayed group didn’t grow.⁸

A large network meta-analysis backs the broader point: for older and mixed populations, protein after exercise was most effective for muscle mass, and a pre-sleep dose most effective for strength.⁵ So for your masters clients, the window is worth respecting — a shake right after the session, or casein before bed, is a genuine lever rather than a superstition.

The per-meal dose also shifts. Pooling dose-response data from young (~22) and older (~71) men, muscle protein synthesis plateaued at about 0.24 g/kg per meal in the young but 0.40 g/kg in the old — a 70-kg older client needs roughly 28 g per meal, not 17 g, to get the same signal.¹¹ And the geriatric consensus sets the floor higher too: the PROT-AGE group recommends 1.0–1.2 g/kg/day for healthy older adults, at least 1.2 g/kg for those who exercise, and 1.2–1.5 g/kg during illness — well above the 0.8 g/kg many of them are told is “enough.”¹³

Evidence grade: moderate on timing, strong on the higher per-meal and daily needs. Consistent signal that timing helps specifically where anabolic resistance is present; the higher dose requirement is backed by dose-response data and a consensus position.

Dose and distribution: 0.25 g/kg, spread out

Once the daily total is handled, this is the highest-value detail. The ISSN’s practical guidance is ~0.25 g/kg (roughly 20–40 g) per meal, eaten every 3–4 hours, with each dose carrying enough leucine (~700–3000 mg) from a complete protein to fully switch on muscle protein synthesis.¹ Most people front-load almost nothing at breakfast and dump their protein at dinner — which is exactly the pattern to fix.

A 12-week trial made the point directly: evenly distributing protein across the day (rather than skewing it to dinner) tended to produce greater gains in lean tissue, with a large effect size.⁷ Same daily total, better result, just by spreading it out. That’s a free win you can coach without anyone buying anything.

Evidence grade: moderate. The per-meal dose is well-supported; the distribution edge is real but from smaller trials.

Type, and the one genuinely useful “hack”

Protein quality matters at the margins. Complete, rapidly-digested, leucine-rich sources — milk proteins like whey and casein, plus meat and mixed sources — are most effective at stimulating muscle protein synthesis, and the network meta-analysis rated milk proteins the preferred supplement type for both mass and strength.⁵ Whole food does the job for most people; a shake is just a convenient way to hit the number. That includes plant-only eating, provided the total is there: in a 12-week trial, habitual vegans and omnivores both brought to 1.6 g/kg/day (soy versus whey to top up) gained the same leg lean mass, the same fibre size, and comparable leg-press strength.¹⁵ Source matters at low intakes and in single-meal lab studies; at a solid daily total with a bit of extra volume, it washes out.

The one timing hack with real support is pre-sleep casein: 30–40 g before bed increases overnight muscle protein synthesis without harming fat metabolism.¹ It’s not magic, but for a client struggling to fit their total into the day, it’s a legitimate slot rather than a marketing story.

Evidence grade: moderate on type; the pre-sleep dose is supported but a small optimisation, not a foundation.

The kidney worry, briefly

The objection you’ll hear most from a client’s partner or GP is that “all that protein damages your kidneys.” For healthy kidneys it doesn’t hold up. A meta-analysis of 28 controlled trials in 1,358 adults without kidney disease compared higher-protein diets (≥1.5 g/kg/day, or ≥20% of energy) with normal or lower intakes and found no difference in the change in kidney filtration rate — higher protein nudges filtration up, which is a normal workload response, not damage.¹⁴ The caveat is real where kidney disease already exists: the PROT-AGE group explicitly carves out people with severe chronic kidney disease, who may need to limit protein.¹³ So: healthy client, no issue; known kidney disease, doctor first.

Evidence grade: strong for safety in healthy adults; the exception for existing kidney disease is a medical boundary, not a coaching one.

What’s being tested next

Here’s the live edge a static macro chart can’t give you. The clinical registry’s protein-and-training pipeline is pointed squarely at questions your clients are about to ask.¹⁶

The big one: protein plus resistance training during GLP-1 (weight-loss drug) use. People losing weight fast on these medications shed muscle alongside fat, and trials are now testing whether higher protein and lifting can protect lean mass through it — the same thread running through the creatine and Zone 2 research. Alongside it: sarcopenia and older-adult dosing — how much, how distributed, and how timed to overcome anabolic resistance — and head-to-head distribution and timing trials to settle the smaller questions. We’ll update this piece as they read out — that’s the point of an evidence page that’s alive instead of frozen.

Your script for Monday

When the next client asks about protein, here’s the whole thing in plain language:

“Get your daily total right and you’ve basically won: aim for around 1.6 to 2.2 grams per kilo of bodyweight, every day, and make sure you’re actually lifting — protein only builds strength on top of training. Spread it across your meals, roughly 20 to 40 grams each, instead of nothing at breakfast and a mountain at dinner. Don’t stress about a magic post-workout window; the anabolic effect lasts all day, so as long as you hit your total it’s fine. The one exception is if you’re older — then taking protein soon after training, or before bed, genuinely helps more. And you don’t need the fancy blend; milk, whey, meat, soy, or a normal shake all do the job — vegan works fine if the total’s there. A big protein meal isn’t wasted either, your body just uses it for longer. And no, it won’t hurt your kidneys unless you already have a kidney problem — then ask your doctor.”

That’s it. No window-watching, no bro-science, no overpriced blends. Just the evidence, translated into something a human can act on — which is the entire job.

Sqwod reads the research so your clients don’t have to. This is coaching information, not medical advice; anything involving a medical condition, pregnancy, medication, or kidney concerns belongs with a qualified professional. Spotted something that needs sharpening? That’s how an evidence page stays honest — tell us and we’ll correct it in public.