How Much Protein Do You Actually Need to Build Muscle?

By Zerxus Team  |  Nutrition

Protein is the most discussed macronutrient in fitness — and also the most misunderstood. You’ve probably heard numbers ranging from 0.8g/kg to 4g/kg. The truth lies in what the research actually says, and it’s simpler than the supplement industry wants you to believe.

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Why Protein Matters for Muscle Building

Muscle is made of protein. When you train, you create micro-damage in muscle fibres. Your body repairs and rebuilds these fibres using amino acids from dietary protein — a process called muscle protein synthesis (MPS). If you don’t provide enough protein, MPS is limited, and your training adaptations are blunted.

This is why protein intake is one of the most critical nutritional variables for anyone serious about building muscle or maintaining strength.

The Evidence: What Does the Research Say?

The most comprehensive meta-analysis on protein and muscle building (Morton et al., 2018, published in the British Journal of Sports Medicine) analysed data from 49 studies and over 1,800 participants. The findings:

• Protein intakes beyond 1.62g per kg of bodyweight per day produced no additional muscle gains
• The upper 95% confidence limit was 2.2g/kg/day — meaning some individuals may benefit from slightly more
• There was no benefit to intakes above 2.2g/kg even in advanced trainees

Practical recommendation: Aim for 1.6–2.2g of protein per kg of bodyweight per day. This range covers the vast majority of people, from beginners to advanced athletes.

Calculating Your Personal Protein Target

Here’s how to calculate your daily protein target:

• Bodyweight × 1.6g = minimum for muscle building
• Bodyweight × 2.0g = solid middle target
• Bodyweight × 2.2g = upper end (useful when in a calorie deficit)

Examples for a 75kg person:

• Minimum: 120g/day
• Middle target: 150g/day
• Upper end: 165g/day

Does Protein Timing Matter?

Protein timing has a smaller effect than total daily intake, but it’s still worth getting right. Spreading protein across 3–5 meals per day maximises muscle protein synthesis compared to consuming the same amount in one or two sittings.

Aim for 30–50g of protein per meal, 3–5 times per day. A pre- or post-workout meal with protein is helpful but not as critical as many people believe — the “anabolic window” is measured in hours, not minutes.

Best High-Protein Foods

Focus on whole food sources first, then supplement if needed:

• Lean meats: chicken breast (~31g/100g), turkey, lean beef
• Fish: tuna (~30g/100g), salmon (~25g/100g), cod
• Eggs: ~6g per egg, 13g per 100g
• Dairy: Greek yoghurt (~10g/100g), cottage cheese (~11g/100g), milk
• Legumes: lentils (~9g/100g cooked), black beans, chickpeas
• Whey protein: ~25g per scoop — a convenient supplement, not a necessity

Do Vegetarians and Vegans Need More Protein?

Plant proteins are generally less bioavailable than animal proteins and often lower in leucine — the key amino acid that triggers muscle protein synthesis. If you eat predominantly plant-based, a slightly higher intake (2.0–2.4g/kg) and prioritising leucine-rich sources (soy, lentils, quinoa) is sensible.

Vegan protein powders (pea + rice blend) can help hit targets without requiring huge food volumes.

What About Protein When Cutting?

During a calorie deficit, protein needs are actually higher — not lower. This is because your body is more likely to break down muscle for energy when calories are scarce. When cutting, aim for the upper end of the range: 2.2–2.4g/kg/day. This preserves muscle while in deficit, which is the entire goal of a cut.

For a full guide to training and adaptation, see our piece on progressive overload — the principle that determines whether your training stimulus is actually producing results.

Can You Eat Too Much Protein?

For healthy individuals, high protein intakes (even 3g/kg) appear to be safe. The concern about kidney damage applies to people with pre-existing kidney disease, not healthy adults. That said, eating more than 2.2g/kg provides no additional muscle-building benefit — it just displaces other macronutrients and adds unnecessary calories.

Frequently Asked Questions

Should I count protein in grams or as a percentage of calories?

Grams per kilogram of bodyweight is a much more useful metric than percentage of calories, because your protein needs are related to your body mass — not your total calorie intake. Use the 1.6–2.2g/kg range and adjust calories separately.

Do I need to drink protein shakes to hit my protein target?

No. Protein shakes are a convenient tool, not a requirement. Many people hit their protein targets entirely through whole foods. If you’re struggling to reach your target from food alone, a shake can help — but prioritise food sources first.

When should I eat my protein relative to my workout?

Within a few hours either side of your workout is fine. Consuming 30–50g of protein in a meal 1–2 hours before training or within 2 hours after covers all practical bases. The exact timing matters far less than hitting your daily total.