How much protein per day to build muscle in the UK?

December 3, 2025 •

3 min read

According to the British Nutrition Foundation, the baseline Reference Nutrient Intake (RNI) for protein is 0.75g per kg of body weight for sedentary adults. However, this figure is a minimum to prevent deficiency, and a significantly higher intake is needed for those looking to build muscle mass, especially when combined with resistance training.

Quick Summary

This guide outlines optimal daily protein intake for muscle growth, using clear calculations based on body weight for UK residents, and details the best food sources and timing for effective gains.

Key Points

Calculate for Muscle Growth: For active UK adults, aim for 1.6-2.2g of protein per kg of body weight daily, far exceeding the sedentary RNI.
Prioritise Whole Foods: Build your diet around high-quality protein sources like lean meats, dairy, eggs, and plant-based alternatives such as tofu and lentils.
Spread Your Intake: Distribute your protein consumption evenly across the day with 3-6 meals and snacks to maximise muscle protein synthesis.
Leverage Supplements for Convenience: Use protein supplements like whey for quick post-workout intake or casein before bed, but remember they are not essential if dietary needs are met.
Don't Overlook Other Macronutrients: Balance your protein intake with adequate carbohydrates for energy and healthy fats for hormone function to optimise muscle growth and overall health.

Your Personal Protein Blueprint: Calculating for UK Muscle Gains

For individuals in the UK aiming to increase muscle mass, determining the correct protein intake is crucial, and it goes beyond the general population's recommendations. While the official RNI of 0.75g per kilogram of body weight is a baseline for health, it's not optimised for muscle hypertrophy. Instead, current research and sports nutrition guidelines suggest a substantially higher amount for active adults and bodybuilders.

The Expert-Backed Range for Muscle Growth

Multiple sources converge on a recommended daily intake for muscle gain. The International Society of Sports Nutrition recommends 1.4–2.0 g/kg of protein, while other reviews suggest aiming higher for maximal hypertrophy. A useful and safe range for most active people to target is between 1.6 to 2.2 grams of protein per kilogram of body weight per day.

For example, if you weigh 80kg:

Lower end for lean mass maintenance: $80kg \times 1.6g/kg = 128g$ of protein per day.
Higher end for maximising growth: $80kg \times 2.2g/kg = 176g$ of protein per day.

Why You Need More Protein When Building Muscle

Resistance training, such as weightlifting, causes microscopic damage to muscle fibres. Protein provides the essential amino acids needed to repair and rebuild these fibres, a process known as muscle protein synthesis (MPS). A higher protein intake ensures a readily available pool of amino acids to fuel this repair process, leading to muscle growth over time. Additionally, a higher protein diet can promote satiety, which is beneficial during a calorie-controlled phase to lose fat while preserving muscle.

Prioritising High-Quality Protein Sources

Not all protein sources are created equal. High-quality protein contains all nine essential amino acids necessary for muscle repair. It's recommended to build meals around a high-quality protein source, aiming for 20-30g per meal.

Sources of High-Quality Protein:

Lean meats (e.g., chicken, turkey, lean beef)
Fish and seafood (e.g., salmon, tuna, mackerel)
Dairy products (e.g., milk, Greek yoghurt, cottage cheese)
Eggs
Soy products (e.g., tofu, tempeh, edamame)
Pulses and beans
Nuts and seeds

Spreading Protein Intake Throughout the Day

While the total daily protein intake is the most important factor, spreading it out evenly across the day can maximise MPS. Many people consume most of their protein at dinner, but research shows that a more balanced distribution can be more effective for muscle growth, particularly in older adults. Aiming for 3 to 6 high-protein meals or snacks is often recommended. Taking some protein, especially a slow-digesting one like casein, before bed can also support overnight recovery.

Do Protein Supplements Help?

Supplements can be a convenient way to meet high protein goals, but they are not essential if you consume enough from whole foods. Whey protein, for instance, is quickly absorbed and ideal post-workout, while casein digests slowly and is better for a sustained release. The "anabolic window"—the belief that protein must be consumed immediately after a workout—is less critical than previously thought, with a two-hour window being more realistic for most individuals. The total daily intake remains the most important factor for muscle development.

Comparison of Protein Sources


Protein Source	Type	Protein Content (approx.)	Absorption Rate	Pros	Cons
Whey Protein	Dairy	~20-30g per scoop	Fast	Highly bioavailable, easy to consume post-workout	Can be expensive, contains dairy
Casein Protein	Dairy	~20-30g per scoop	Slow	Provides sustained amino acid release, ideal for before bed	Less convenient for immediate post-workout
Chicken Breast (100g)	Meat	~31g	Medium	Excellent source of lean, complete protein	Requires cooking and preparation
Greek Yoghurt (170g)	Dairy	~17g	Medium	High in protein, convenient snack, contains calcium	Can be high in sugar if flavoured
Lentils (100g cooked)	Plant	~9g	Slow	High in fibre, affordable, and vegan-friendly	Incomplete protein, requires larger serving sizes
Tofu (100g)	Plant	~17g	Medium	Versatile, complete plant-based protein	Less flavourful on its own

Conclusion

To build muscle effectively in the UK, active individuals should target a daily protein intake between 1.6 and 2.2g per kg of body weight, significantly higher than the standard RNI. Distribute this intake across multiple meals and snacks throughout the day, focusing on high-quality, whole-food protein sources. While supplements like whey or casein can be useful for convenience, they are not a prerequisite for muscle growth. Consistency with your protein intake, combined with an effective resistance training programme, is the most crucial strategy for achieving your muscle-building goals.

Heart UK recommends plant-based proteins as a priority for cardiovascular health.

Frequently Asked Questions

The Reference Nutrient Intake (RNI) for protein in the UK is 0.75g per kg of body weight, intended for sedentary adults to prevent deficiency. For muscle growth, a higher intake is needed to fuel the repair and rebuilding of muscle fibres after exercise.

Multiply your body weight in kilograms by a factor between 1.6 and 2.2. For example, an 80kg person would aim for 128-176g of protein per day for optimal muscle building.

While the "anabolic window" was a popular concept, research suggests it is much wider than initially believed. Consuming protein within a two-hour window post-exercise is sufficient for muscle repair and growth.

For healthy individuals, moderate increases in protein intake are safe. However, consuming excessive amounts (over 2g/kg per day) for prolonged periods could potentially put extra strain on the kidneys, especially for those with pre-existing conditions.

Yes. Plant-based proteins can effectively support muscle growth. While some plant proteins are incomplete, mixing sources like beans and rice or using a complete protein like soy ensures you get all essential amino acids. Plant-based protein powders also offer a convenient boost.

Aiming for 20-30g of protein per meal is a good strategy to effectively stimulate muscle protein synthesis. Spreading your total daily target across 3-6 meals helps maintain a consistent supply of amino acids.

Yes, research indicates that consuming a slow-digesting protein, such as casein (found in Greek yoghurt or cottage cheese), before sleep can enhance muscle recovery and promote muscle protein synthesis overnight.