Protein: how much do you actually need, and does timing matter?

Protein: how much do you actually need, and does timing matter?

Protein might be the most anxiety-inducing macronutrient in modern nutrition culture. Official guidance suggests most people already eat plenty; gym culture insists nobody eats enough; and the supplement aisle would like you worried about it indefinitely. The truth sits in between, and it depends heavily on which question you’re actually asking: how much protein keeps you healthy, versus how much supports a specific goal like building muscle.

What the official guidance actually says

The UK’s Reference Nutrient Intake for protein is 0.75g per kilogram of body weight per day, a figure set by the Department of Health in 1991 and still the basis for current guidance. For a 70kg adult, that works out to about 52.5g a day — roughly two palm-sized portions of protein-rich food. It’s worth being precise about what this number represents: it’s calculated from nitrogen balance studies to be sufficient for 97.5% of the population, meaning it’s designed to prevent deficiency in nearly everyone, not to optimise anything. On average, UK adults already eat more than this — surveys put typical intake at around 85g/day for men and 67g/day for women.

That’s the reassuring part: genuine protein deficiency is rare in the UK on an ordinary varied diet. It’s also, for anyone training seriously or trying to preserve muscle with age, an incomplete answer, because “enough to avoid deficiency” and “enough to support a specific physical goal” are different questions with different numbers attached.

What the resistance-training research actually supports

For people doing regular resistance training, the sports nutrition literature converges on a noticeably higher figure than the RNI. A systematic review and meta-regression covering 49 studies and over 1,800 participants found that protein supplementation continued to support gains in fat-free mass up to intakes of roughly 1.6g/kg/day, beyond which additional protein didn’t meaningfully add further benefit for most people. Other reviews put the useful upper range for active individuals at 1.6–2.2g/kg/day, with the higher end applying more to advanced trainees or people in a calorie deficit trying to preserve muscle while losing fat.

Translating that for a 70kg adult training regularly: somewhere around 112–150g of protein a day, roughly double to triple the RNI figure — a meaningful gap, and part of why “how much protein do I need” gets such different answers depending on who’s asking.

The anabolic window: mostly myth

One of the most persistent pieces of gym folklore is the “anabolic window” — the idea that you have a narrow 30-to-60-minute post-workout period in which you must consume protein, or you’ll forfeit most of the muscle-building benefit of your session. This has been directly tested, and doesn’t hold up well.

A 2013 meta-analysis by Brad Schoenfeld and colleagues, published in the Journal of the International Society of Sports Nutrition, found that when total daily protein intake is already adequate, the specific timing of protein around a workout has a limited independent effect on strength and muscle gains — total intake matters more than precision timing. A follow-up randomised trial by the same research group, directly comparing protein consumed immediately before versus immediately after training, found no meaningful difference in strength, muscle size or body composition outcomes between the two groups. Reviewers now generally describe any genuine “window” as considerably wider than originally claimed — plausibly several hours around a training session, if it matters at all once total daily intake is accounted for.

None of this means timing is completely irrelevant. Research on distributing protein across the day — roughly 3–4 meals each containing a meaningful dose, rather than concentrating most of it at one meal — has somewhat better evidence behind it for maximising muscle protein synthesis over 24 hours, particularly in older adults, whose bodies respond less efficiently to smaller protein doses (a phenomenon researchers call “anabolic resistance”). That’s a genuinely useful practical takeaway; a strict pre/post-workout supplement ritual is not.

Who actually needs to think harder about this

Three groups have real reasons to pay closer attention to protein beyond the RNI: people doing regular resistance training (covered above); older adults, since research on UK adults aged 65–89 found fewer than half were meeting even the basic RNI, let alone the higher figures now recommended for preserving muscle with age; and anyone in a calorie deficit for weight loss, where higher protein intake (towards 1.6–2.0g/kg/day) helps protect muscle mass and supports satiety during restriction.

The honest takeaway

If you’re not training seriously and eating a varied UK diet, you’re probably already getting enough protein without thinking about it — the RNI is a low bar most people clear by default. If you’re training regularly, trying to preserve muscle with age, or cutting calories, aiming for somewhere in the 1.2–2.0g/kg/day range, spread reasonably evenly across the day, is better supported by the evidence than either ignoring protein entirely or obsessing over a post-workout timer.

FAQs

What’s the UK’s official protein recommendation?

0.75g per kg of body weight per day (the Reference Nutrient Intake) — around 52g for a 70kg adult. It’s a deficiency-prevention minimum, not an optimal intake for training or ageing.

Do I really need double the RNI if I go to the gym?

For people doing regular resistance training, research supports intakes up to roughly 1.6g/kg/day for maximising muscle gains, which is meaningfully higher than the RNI — though going well beyond that shows diminishing returns in most studies.

Is the “anabolic window” real?

Not in the strict 30-60-minute sense it’s usually described. Meta-analyses and direct trials have found total daily protein intake matters far more than precise timing around a workout; any genuine window is likely several hours wide, if it matters much at all once total intake is adequate.

Should I spread protein across the day rather than eat it all at dinner?

There’s reasonable evidence for this, especially in older adults, who need higher per-meal protein doses to stimulate muscle protein synthesis efficiently as anabolic resistance develops with age.

Can eating too much protein cause harm?

In otherwise healthy adults, high protein intakes (studies have tested up to around 4.4g/kg/day) haven’t shown adverse effects on body composition or general health in short-to-medium-term studies, though very high intakes offer no additional muscle-building benefit beyond roughly 1.6–2.2g/kg/day.

Do older adults need more protein than younger adults?

Evidence suggests so — ageing is linked to anabolic resistance, meaning muscles respond less efficiently to a given protein dose, which is part of why organisations like ESPEN recommend higher per-kg intakes (around 1.2g/kg/day or more) for older adults than the general RNI.