Every fitness goal — bulking, cutting, recomposition, performance, or maintenance — comes down to the same three levers: how much protein, carbs, and fat you eat each day. This is the complete macronutrient guide: how to calculate the right split for your goal, what each macro actually does in the body, and how to adjust across a 12-month training cycle. Everything here is anchored to peer-reviewed evidence (Morton 2018, Helms 2014, Iraki 2019, Aragon-Schoenfeld) rather than diet-culture heuristics.

What Macros Are and Why They Matter

Macronutrients are the three energy-providing components of food:

  • Protein: 4 kcal per gram. Builds and repairs tissue, provides amino acids, contributes to satiety.
  • Carbohydrates: 4 kcal per gram. Primary fuel for training and brain function, replenishes muscle glycogen.
  • Fat: 9 kcal per gram. Hormone production, absorbs fat-soluble vitamins (A, D, E, K), long-duration energy.

Total calories determine whether you gain, lose, or hold weight. Macro split determines what tissue you gain or lose. A 500 kcal surplus eaten as 100% carbs builds primarily fat and glycogen; the same 500 kcal surplus with 2 g/kg protein builds muscle. This is why macros exist as a concept separate from calorie counting.

The Complete Macro Calculation Workflow

Step 1 — Calculate TDEE

Every macro plan starts with Total Daily Energy Expenditure. Use the Mifflin-St Jeor formula (validated in the 2005 accuracy analysis):

  • Men BMR: (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
  • Women BMR: (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
  • TDEE: BMR × activity multiplier (1.2 sedentary to 1.9 extremely active)

Full breakdown of activity multipliers and how to verify your real TDEE in the TDEE complete guide.

Step 2 — Apply Goal Adjustment

  • Fat loss: TDEE − 15-25% (typically 300-600 kcal below)
  • Maintenance / recomp: TDEE ±5%
  • Lean bulk: TDEE + 200-300 kcal
  • Standard bulk: TDEE + 400-500 kcal
  • Aggressive bulk: TDEE + 700+ kcal (fast strength gain, more fat)

Step 3 — Lock Protein First

Protein is the load-bearing macro — everything else adjusts around it. Set protein by goal:

  • Fat loss (cut): 2.0-2.4 g/kg bodyweight
  • Muscle gain (bulk): 1.8-2.2 g/kg
  • Recomposition: 2.0-2.2 g/kg
  • Maintenance: 1.4-1.8 g/kg (or up to 1.6 g/kg lean mass)

These come from the Morton et al. 2018 meta-analysis of 49 studies. Above 2.2 g/kg during a bulk, additional protein produces diminishing returns; during a cut, higher protein (up to 2.4 g/kg) helps preserve lean mass in the deficit.

Step 4 — Set Fat (Minimum Threshold)

Fat has a floor for hormone function and vitamin absorption:

  • Minimum: 0.6-0.8 g/kg bodyweight (below this, hormone function degrades over weeks)
  • Standard: 0.9-1.1 g/kg
  • Higher-fat approach: 1.2-1.5 g/kg (for people who thrive on lower-carb intakes)

Iraki et al. (2019) recommend a minimum of 20% of total calories from fat during any dieting phase to preserve testosterone and menstrual function.

Step 5 — Fill Remaining Calories with Carbs

Once protein and fat are set, carbs get whatever is left in the calorie budget:

Remaining kcal = Target − (protein grams × 4) − (fat grams × 9)

Carbs grams = Remaining kcal ÷ 4

Carbs are the flexible macro — they scale up on training days for performance, down on rest days if calorie targets require it. Athletes running high volume will land at 4-7 g/kg carbs; sedentary dieters may sit at 2-3 g/kg.

Worked Example: 80 kg Man, Muscle Gain

Male, 30 years, 178 cm, 80 kg, moderately active (1.55):

  1. BMR = (10 × 80) + (6.25 × 178) − (5 × 30) + 5 = 1,767 kcal
  2. TDEE = 1,767 × 1.55 = 2,739 kcal
  3. Bulk target = 2,739 + 300 = ~3,040 kcal
  4. Protein = 80 × 2.0 = 160 g = 640 kcal
  5. Fat = 80 × 1.0 = 80 g = 720 kcal
  6. Carbs = (3,040 − 640 − 720) ÷ 4 = 420 g

Final macros: 160P / 420C / 80F on 3,040 kcal. Full example variations in the macro calculator for muscle gain guide.

Worked Example: 65 kg Woman, Fat Loss

Female, 28 years, 165 cm, 65 kg, lightly active (1.375):

  1. BMR = (10 × 65) + (6.25 × 165) − (5 × 28) − 161 = 1,380 kcal
  2. TDEE = 1,380 × 1.375 = 1,898 kcal
  3. Cut target = 1,898 × 0.80 = ~1,520 kcal (−20% deficit)
  4. Protein = 65 × 2.2 = 143 g = 572 kcal
  5. Fat = 65 × 0.7 = 46 g = 414 kcal
  6. Carbs = (1,520 − 572 − 414) ÷ 4 = 134 g

Final macros: 143P / 134C / 46F on 1,520 kcal. Full example variations in macro calculator for fat loss.

Popular Macro Splits Explained

40/40/20 (Recomposition Standard)

40% protein / 40% carbs / 20% fat. Elevated protein for lean tissue, moderate carbs for training performance, floor-level fat. Works well for intermediate lifters maintaining bodyweight while trying to slowly reshape body composition.

40/30/30 (Zone Diet Legacy)

40% carbs / 30% protein / 30% fat. Popularized by the Zone Diet in the 1990s. Moderate everything — reasonable maintenance split, though most modern approaches push protein higher for lifters.

30/40/30 (Balanced Athletic)

30% protein / 40% carbs / 30% fat. Common recommendation for general athletic populations. Not optimized for aggressive muscle gain or fat loss but sustainable long-term.

Leangains 5:2 (Berkhan)

Martin Berkhan's Leangains split cycles macros: high carb / low fat on training days, low carb / higher fat on rest days, protein constant. See the Leangains macro calculator for the full protocol.

Keto (Low-Carb / High-Fat)

~70-75% fat / 20-25% protein / 5-10% carbs. Restricts carbs below 30-50 g/day to induce ketosis. Works for fat loss primarily via satiety and calorie displacement; not optimal for high-volume lifters due to reduced glycogen availability.

The Non-Negotiable: Protein First

Across all fitness goals, protein intake is the single macro that most directly affects outcomes. The Morton 2018 meta-analysis (49 RCTs, 1,863 subjects) established:

  • 1.6 g/kg is the threshold for maximum lean mass gain from resistance training
  • Above 1.6 g/kg produces small additional benefit; above 2.4 g/kg produces essentially none
  • During caloric deficit, higher protein (2.0-2.4 g/kg) preserves more lean mass
  • Distribution: 3-5 meals with 0.3-0.4 g/kg per meal maximizes protein synthesis

If you hit the protein target and rough calorie target, the exact carb/fat split matters far less than most content suggests. Protein first, calories second, everything else is fine-tuning.

How Macros Change Across Goals

Cutting Phase (12-16 Weeks)

  • Deficit: 20-25% below TDEE
  • Protein: 2.2-2.4 g/kg
  • Fat: 0.6-0.8 g/kg (minimum viable)
  • Carbs: fill remainder
  • Recalculate every 4 weeks as bodyweight drops

Bulking Phase (16-24 Weeks)

  • Surplus: +200-500 kcal above TDEE
  • Protein: 1.8-2.0 g/kg
  • Fat: 0.9-1.1 g/kg
  • Carbs: fill remainder (typically 4-7 g/kg for lifters)
  • Recalculate every 4-6 weeks as bodyweight climbs

Recomposition Phase (Ongoing)

  • Calories: at or ±5% of TDEE
  • Protein: 2.0-2.2 g/kg
  • Fat: 0.9-1.0 g/kg
  • Carbs: fill remainder
  • Expect slow progress — measured in months, not weeks

Maintenance / Off-Season

  • Calories: at TDEE
  • Protein: 1.4-1.8 g/kg
  • Fat: 0.8-1.2 g/kg
  • Carbs: whatever feels sustainable

Common Macro Calculation Mistakes

  • Setting protein too low. "1 g/lb" (~2.2 g/kg) is often over-prescribed for bulks but appropriate for cuts. Most people undershoot during dieting phases where protein matters most.
  • Fat below 0.6 g/kg for extended periods. Long-term ultra-low-fat cuts (below 15% of calories) suppress hormones. Add fat before dropping carbs further.
  • Using bodyweight instead of lean mass for protein. For very lean or very obese individuals, protein per kg of lean mass is more accurate than per kg of bodyweight.
  • Never recalculating. A macro plan from 6 months ago is stale — bodyweight has moved, activity has moved, TDEE has moved.
  • Chasing precision that doesn't exist. Hitting macros ±10 g/day is fine. Obsessing over ±1 g adds no benefit.

How Meal Timing Fits (or Doesn't) with Macros

The current evidence (Aragon-Schoenfeld 2013, Schoenfeld 2020):

  • Anabolic window: extends 4-6 hours around training. Post-workout protein within 30 minutes matters less than daily total.
  • Meal frequency: 3-5 meals per day is sufficient for maximizing protein synthesis. More frequent meals produce no additional benefit if daily totals are hit.
  • Pre-sleep protein: A 30-40 g casein or whole-food protein serving 1-2 hours before bed slightly increases overnight muscle protein synthesis (Res et al. 2012).
  • Carb timing: Around workouts is convenient but not required. Total daily carbs matter more than exact timing.

Popular Macro Approaches Compared

  • IIFYM (If It Fits Your Macros): Any food that fits daily macro targets. Maximum flexibility. Works for people with strong impulse control around trigger foods.
  • Flexible Dieting (RP-style): Structured macro targets with prescribed food quality ratios (80-90% whole foods, 10-20% flexibility). See Leangains-style variations.
  • Meal Plan (traditional): Prescribed exact foods and quantities. Zero flexibility but zero decision fatigue.
  • Intuitive Eating: No tracking; eat to hunger and satiety cues. Works for maintenance for some; unreliable for aggressive fat loss or muscle gain phases.

Related Cluster Reading

Bottom Line

Every macro plan reduces to five steps: calculate TDEE, apply your goal adjustment, lock protein at 1.8-2.4 g/kg based on phase, set fat at 0.7-1.1 g/kg, and fill carbs with what's left. Protein is the non-negotiable input; everything else is fine-tuning around it. Recalculate every 4-6 weeks as bodyweight and activity shift, and stop treating macros as more precise than they need to be — hitting daily totals within ±10 g is a rounding error, not a failure. The plan that works is the plan that gets executed for 12+ weeks straight.