Building muscle requires two things working together: a sufficient training stimulus and the right nutritional environment. Macronutrients — protein, carbohydrates, and fat — each play a distinct role in supporting muscle growth, recovery, and performance. Getting the balance right can meaningfully accelerate your results.
Start with a calorie surplus
Muscle tissue cannot be built without adequate energy. Trying to gain significant muscle while eating at or below maintenance is possible for beginners, but for most trained individuals, a calorie surplus is necessary to create the conditions for hypertrophy.
The evidence points to a modest surplus of 200–350 calories above maintenance (approximately 10–15% above TDEE) as the optimal range for lean muscle building. A larger surplus does not accelerate muscle growth — it primarily increases fat accumulation alongside the muscle you gain.
Protein: the most critical macronutrient
Protein provides the amino acids required to build and repair muscle tissue. It is the single most important dietary variable for muscle gain, and it is where most people's attention should be focused.
The current scientific consensus, drawn from multiple meta-analyses, is that 1.6–2.2 grams of protein per kilogram of body weight per day maximises muscle protein synthesis in most individuals engaged in resistance training. Going above 2.2g/kg provides no additional muscle-building benefit for most people, though it is not harmful.
Practical protein targets
| Body weight | Minimum (1.6g/kg) | Optimal (2.0g/kg) |
|---|---|---|
| 60 kg | 96g/day | 120g/day |
| 75 kg | 120g/day | 150g/day |
| 90 kg | 144g/day | 180g/day |
| 105 kg | 168g/day | 210g/day |
Spreading protein evenly across 3–5 meals per day is more effective than consuming the same total in 1–2 sittings, as this maximises the number of times muscle protein synthesis is stimulated throughout the day.
Carbohydrates: fuel for performance and recovery
Carbohydrates are the primary fuel source for high-intensity resistance training. They are stored as glycogen in muscles and the liver, and glycogen depletion is directly linked to reduced training performance, which in turn limits the training stimulus for muscle growth.
For muscle building, carbohydrates should make up the largest share of your calorie intake after protein needs are met — typically 40–55% of total calories. Prioritising carbohydrate intake around workouts (pre and post-training) maximises their impact on performance and recovery.
High-quality carbohydrate sources include:
- Rice, oats, and other whole grains
- Potatoes and sweet potatoes
- Fruits and vegetables
- Legumes (which also provide protein)
Dietary fat: essential but not dominant
Fat plays a critical role in hormone production — including testosterone and other anabolic hormones — cell membrane integrity, and the absorption of fat-soluble vitamins. Dropping fat intake too low can suppress hormone levels and impair recovery.
A healthy minimum is around 0.7–1.0g of fat per kilogram of body weight per day, which for most people works out to 20–30% of total calories. There is no significant muscle-building benefit to eating more fat beyond this level, so remaining calories should come from carbohydrates.
A practical macro split for muscle gain
Based on the above, a reasonable macro split for muscle building looks like this:
- Protein: 25–30% of calories (prioritise hitting 1.6–2g/kg first)
- Carbohydrates: 45–55% of calories
- Fat: 20–25% of calories
Use the Calories & Macros calculator to generate your personalised targets based on your body weight and activity level. The "Build muscle" option applies these principles automatically.
Timing considerations
While total daily intake matters most, strategic timing can provide a small additional benefit:
- Pre-workout (1–2 hours before): Prioritise carbohydrates and moderate protein to fuel the session and reduce muscle breakdown during training.
- Post-workout (within 2 hours): A protein-rich meal or shake with carbohydrates helps initiate recovery and replenish glycogen. The "anabolic window" is wider than once thought — within a few hours is sufficient.
- Before bed: Casein protein (found in cottage cheese, Greek yoghurt, and casein powder) digests slowly and may support overnight muscle protein synthesis.
The bottom line
For muscle building, the hierarchy of importance is: total calories (slight surplus) > total protein (1.6–2g/kg) > carbohydrate and fat balance > meal timing. Getting the first two right will account for the vast majority of your results. Optimising the rest provides a smaller, though still meaningful, additional benefit.