Macronutrients — protein, carbohydrates, and fat — are the three categories of nutrients that provide energy and the raw materials for every bodily process. Understanding what each does and how much you need is the foundation of any effective nutrition approach for fitness.
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Protein: The Building Block
Protein provides 4 calories per gram and is composed of amino acids — the structural units of muscle, enzymes, hormones, and immune cells. It is the most important macronutrient for anyone doing resistance training. As covered in detail in our protein guide, 1.6–2.2g per kg of bodyweight per day is the evidence-based target. Protein is also the most satiating macronutrient, making it important for fat loss as well as muscle building.
Carbohydrates: The Performance Fuel
Carbohydrates provide 4 calories per gram and are stored in muscles and the liver as glycogen — the primary fuel for high-intensity exercise. When you lift weights or do intense cardio, you draw primarily on glycogen. Depleted glycogen impairs training performance significantly.
Carbohydrates are not inherently fattening — they cause fat gain only when consumed in excess of total calorie needs. For strength athletes, carbohydrates are your best friend: eat them around training for performance and recovery.
Fat: The Hormone and Health Macronutrient
Dietary fat provides 9 calories per gram — the most energy-dense macronutrient. Fat is essential for testosterone production, vitamin absorption (A, D, E, K are fat-soluble), joint lubrication, and cell membrane integrity. Do not go below 0.5g per kg of bodyweight — this impairs hormone production.
Sources matter: prioritise unsaturated fats (olive oil, avocado, nuts, oily fish) and include moderate saturated fat (dairy, meat). Trans fats (partially hydrogenated oils) have no place in a performance diet.
How to Set Your Macros
- Step 1: Calculate your TDEE (bodyweight in kg × 33–38)
- Step 2: Set protein: 1.6–2.2g × bodyweight in kg
- Step 3: Set fat: minimum 0.5–1g × bodyweight in kg
- Step 4: Fill remaining calories with carbohydrates
- Step 5: Adjust calorie total based on goal (surplus for muscle, deficit for fat loss)
Do Macros Matter More Than Calories?
Calories determine weight change. Macros determine body composition — the ratio of muscle to fat. You can be in a calorie deficit eating mostly fat and carbs and lose muscle; or in a deficit with high protein and maintain muscle. For performance and physique, both total calories and macronutrient distribution matter. See the full nutrition plan for muscle growth for practical application.
Frequently Asked Questions
Should I avoid carbs at night?
No. The timing of carbohydrate intake matters less than total daily intake. Eating carbs at night is not inherently fattening — consuming more calories than you expend is what causes fat gain, regardless of when those calories are consumed.
What is the best macro split for fat loss?
A calorie deficit with high protein (2.0–2.4g/kg) is the most important factor. Carbohydrates and fat can be adjusted based on preference — research shows that as long as protein is high and calories are in deficit, the carb-to-fat ratio matters relatively little for fat loss outcomes.
Can I build muscle on a low-carb diet?
Yes, but it is harder. Carbohydrates enhance training performance by replenishing glycogen, and glycogen availability affects how hard you can train. Low-carb approaches can work for building muscle but require higher fat intake and may result in slightly lower training performance.
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