How the Macronutrient Calculator Works
This calculator determines your optimal daily intake of the three macronutrients — protein, carbohydrates, and fat — based on your individual stats and goals.
Step 1: Calculate Your Baseline
The calculator estimates your basal metabolic rate (BMR) using the Mifflin-St Jeor equation, which is considered the most accurate predictive formula for most adults:
- Men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5
- Women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161
Step 2: Apply Activity Multiplier
Your BMR is multiplied by an activity factor to estimate your Total Daily Energy Expenditure (TDEE):
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.2 | Desk job, little exercise |
| Lightly Active | 1.375 | Light exercise 1-3 days/week |
| Moderately Active | 1.55 | Moderate exercise 3-5 days/week |
| Very Active | 1.725 | Hard exercise 6-7 days/week |
| Extremely Active | 1.9 | Athlete or very physical job + training |
Step 3: Set Your Goal
- Fat Loss: 15-25% caloric deficit from TDEE
- Maintenance: Match TDEE
- Muscle Gain: 10-20% caloric surplus above TDEE
- Body Recomposition: Slight deficit with high protein
Step 4: Distribute Macronutrients
Based on your goal, the calculator distributes your total calories across macronutrients using evidence-based ratios.
Macro Distribution by Goal
Fat Loss (High Protein)
- Protein: 35-40% of calories (1.0-1.2g per pound of body weight)
- Fat: 25-30% of calories
- Carbohydrates: Remaining calories
Higher protein during a deficit preserves lean mass and supports satiety.
Muscle Gain
- Protein: 25-30% of calories (0.8-1.0g per pound)
- Fat: 20-25% of calories
- Carbohydrates: 45-55% of calories
Higher carbohydrate intake supports training performance and recovery.
Ketogenic
- Protein: 20-25% of calories
- Fat: 70-75% of calories
- Carbohydrates: 5-10% of calories (typically under 50g/day)
Balanced / Maintenance
- Protein: 25-30% of calories
- Fat: 25-30% of calories
- Carbohydrates: 40-50% of calories
Why Protein Matters Most
Regardless of your overall goal, protein is the most important macronutrient to get right:
- Muscle preservation: Adequate protein prevents muscle loss during caloric deficit
- Thermic effect: Protein requires more energy to digest than carbs or fat (20-30% vs. 5-10%)
- Satiety: Protein is the most satiating macronutrient
- Hormone support: Amino acids are precursors to hormones and neurotransmitters
For anyone on a TRT or peptide protocol, protein requirements may be higher due to increased capacity for muscle protein synthesis.
Common Mistakes
- Under-eating protein: Most people eat far less protein than optimal, especially over age 40
- Fearing dietary fat: Adequate fat is essential for hormone production, especially testosterone
- Ignoring fiber: Within your carbohydrate target, aim for 25-35g of fiber daily
- Not adjusting for body composition changes: Recalculate every 4-6 weeks as your weight changes
How to Use Your Results
The calculator provides daily targets in grams. To put these into practice:
- Track for 2-4 weeks using an app like MyFitnessPal or Cronometer to build awareness
- Focus on protein first — hit your protein target and the rest tends to fall into place
- Allow flexibility — hitting within 10% of your targets daily is sufficient for results
- Reassess regularly — as your body changes, your macro needs change too