How Much Protein Do You Need to Build Muscle?

The Evidence-Based Answer

For most actively training adults seeking to build muscle, the evidence points to a daily protein intake of 1.6 to 2.2 grams per kilogram of bodyweight. This is the range consistently supported across the best-designed studies, and it is where meaningful muscle protein synthesis is sustained throughout the day.

Below 1.6g/kg, muscle building is compromised. Above 2.2g/kg, additional benefit is marginal for most people — though there are specific circumstances where higher intakes are justified, as covered below.

For a 75kg person, 1.6–2.2g/kg translates to 120–165g of protein per day. For an 85kg person, 136–187g. Supplementation becomes far easier once you understand the fundamentals, which we break down in The Complete Guide to Protein Powder — Whey, Isolate & Beyond.

Where the Recommendation Comes From

The 1.6–2.2g/kg range is not a rough estimate. It is the output of a substantial body of research, including meta-analyses of controlled trials, dose-response studies, and nitrogen balance methodology.

A landmark 2018 meta-analysis — one of the most comprehensive analyses of protein and muscle growth to date, covering 49 studies and 1,800 participants — found that protein intakes beyond 1.62g/kg/day produced no statistically significant additional muscle mass gains in resistance-trained individuals. The upper bound of 2.2g/kg is retained as a practical ceiling to account for individual variation, training intensity, and the limits of measurement precision.

Arthur Fairhurst was working with athletes on protein requirements long before this research was published. The principles he applied in the 1970s and 1980s — based on direct experience training elite athletes and studying the available science — are consistent with what the evidence has since confirmed. Expertise built over decades tends to look like this.

Does Everyone Need the Same Amount?

No. The 1.6–2.2g/kg range is a reliable target for most active adults, but several factors shift where, within — and occasionally outside — that range you should aim.

Training Status

Beginners to resistance training respond more readily to lower protein intakes than experienced athletes. A newer trainee may see excellent muscle growth at 1.6g/kg. An advanced athlete, whose muscles have adapted and require a stronger stimulus and greater protein supply to continue progressing, benefits from the higher end of the range.

Training Volume and Intensity

Higher training volume — more sessions, more sets, greater total work — creates greater muscle protein breakdown and a correspondingly higher demand for dietary protein to support repair and growth. Those training five or six days a week at high intensity should target the upper end of the range or slightly above it.

Age

Muscle protein synthesis efficiency declines with age. Older adults — broadly, those over 50 — have a blunted anabolic response to any given protein dose compared to younger individuals. This means they need more protein per kilogram of bodyweight to achieve the same muscle-building stimulus. Research increasingly supports intakes of up to 2.0–2.4g/kg for older adults who are actively training.

This is one of the most clinically significant areas of protein research — and one where supplementation plays a particularly important role, since appetite often decreases with age while requirements increase.

Calorie Deficit

When total calorie intake is restricted — during a cutting phase, or for weight management — the body faces a greater risk of breaking down muscle tissue for energy. Higher protein intake during a deficit helps preserve lean mass. In this context, intakes at the top of the range (2.0–2.4g/kg or even slightly above) are supported by the evidence as a muscle-protective strategy. If you’re in a calorie deficit, our breakdown of The Best Protein Powder for Weight Loss shows which formulations genuinely support fat loss while preserving muscle.

Body Composition

Protein requirements are more accurately calculated against lean body mass than total bodyweight. A person carrying significant body fat has a lower lean mass relative to their total weight, so calculating against total bodyweight may overstate their requirements. For most people, this distinction is minor — but for those at higher body fat percentages, calculating against lean mass is more precise.

Quick Reference: Daily Protein Targets

Spreading Protein Across the Day

Total daily intake is the most important variable — but how that protein is distributed across the day also matters.

Muscle protein synthesis is stimulated by individual protein doses. A dose of roughly 20–40g of high-quality protein is sufficient to maximally stimulate synthesis in a single sitting for most people; larger doses do not produce a proportionally greater response at that moment, though the protein is still absorbed and used. This is the basis for the recommendation to distribute intake across three to five eating occasions rather than concentrating it in one or two large meals.

In practice, if your daily target is 160g of protein, four meals or intake occasions providing 35–45g each is a more effective strategy than two meals providing 80g each. Protein shakes make this distribution practical — a shake before or after training, and whole food protein at meals, naturally spreads intake across the day.

For a full breakdown of per-meal absorption, see our guide: How Much Protein Can Your Body Absorb in One Meal?

How Much Protein Can You Get From Food Alone?

It is entirely possible to hit daily protein targets from whole foods — chicken breast, eggs, fish, Greek yoghurt, cottage cheese, red meat — but it requires consistent planning and a fairly high food volume. A typical unrestricted UK diet provides somewhere between 60 and 90g of protein per day — meaningfully below the 1.6–2.2g/kg target for a 75–85kg active adult.

Protein powder is not a replacement for a nutritious diet. It is a practical supplement to it — a fast, precise, portable source of high-quality protein that makes hitting daily targets achievable without structuring every meal around protein volume. One or two shakes per day, alongside quality whole food sources at meals, is the approach most active people find sustainable.

Why Protein Quality Matters

Not all proteins are equally effective for muscle building. The key metric is leucine content — leucine is the branched-chain amino acid that most directly triggers muscle protein synthesis. Whey protein has one of the highest leucine contents of any protein source, which is why it has been the benchmark in sports nutrition for decades.

Beyond leucine, the completeness of the amino acid profile matters — all nine essential amino acids need to be present for full muscle protein synthesis to occur, as does the digestibility and absorption rate of the protein source.

For those who want flavour without compromising quality, Vanilla Protein Powder: Our Formulations Explained breaks down how we build a clean, high‑leucine blend.

Whey protein ensures that what the label states is what you receive: the protein content is accurate, the amino acid profile is intact, and no undisclosed additions or inferior substitutes are diluting the product. When you are deliberately consuming 150–180g of protein per day, the quality of each gram matters.

What About Mass Gainers?

For those who struggle to consume enough total calories — not just protein — to support muscle growth, a mass gainer provides both the protein and the calorie surplus needed. MASS 4000 is formulated specifically for this: a high-calorie, high-protein combination for those whose appetite or lifestyle makes a calorie surplus through food alone difficult to achieve.

A mass gainer is not the right choice for those who are already at or above their calorie target and simply want more protein. For that, a standard whey concentrate or isolate is the appropriate tool.

To understand when a mass gainer is appropriate, our guide Mass Gainers vs Protein Shakes: What’s the Difference? clarifies the roles of each.

The Bottom Line

Hit 1.6–2.2g of protein per kilogram of bodyweight every day, from high-quality sources, distributed across your meals and supplementation. Do this consistently, train hard, and sleep properly. Everything else — timing, specific protein sources, per-meal optimisation — is secondary.

The fundamentals are not complicated. They are just consistent. That is what 47 years of working with athletes has taught us.