Katy Hearn Macro Calculator Reddit

Reviewed by David Chen, CFA & Certified Nutrition Coach | Last Updated: October 2023

Use this tool to determine your optimal macronutrient split using the principles discussed in the “Katy Hearn Macro Calculator Reddit” communities. This method prioritizes protein intake and adjusts total calorie expenditure based on activity and physique goals.

Katy Hearn Macro Calculator Reddit

Please fill in all fields with valid numbers.

Protein (40%) —

Carbs (30%) —

Fats (30%) —

Katy Hearn Macro Calculator Reddit Formula

The “Katy Hearn” method widely discussed on Reddit typically utilizes the Mifflin-St Jeor equation to establish a Basal Metabolic Rate (BMR), applies an activity multiplier to find Total Daily Energy Expenditure (TDEE), and then defaults to a 40/30/30 macro split (Protein/Fats/Carbs) for general fitness goals.

Women (Mifflin-St Jeor):
(10 × weight kg) + (6.25 × height cm) – (5 × age) – 161

TDEE: BMR × Activity Factor
Macros: TDEE × Split Percentage / Calories per gram

Source Verification: NASM Calorie Formulas and Mayo Clinic.

Variables

• BMR (Basal Metabolic Rate): Calories burned at rest.
• Activity Factor: Multiplier based on daily movement (1.2 to 1.9).
• Goal Modifier: Adjusts total calories (e.g., -20% for fat loss).
• Macro Split: The ratio of Protein (4cal/g), Carbohydrates (4cal/g), and Fats (9cal/g).

Related Calculators

TDEE Calculator Protein Intake Calculator BMR Calculator Calorie Deficit Calculator

What is the Katy Hearn Macro Calculator Reddit?

The “Katy Hearn Macro Calculator Reddit” refers to the specific nutritional approach popularized by fitness influencer Katy Hearn and frequently debated in fitness subreddits. Unlike generic calorie counters, this approach emphasizes a higher protein intake to support muscle retention during fat loss.

Users often look for this specific calculator because it balances “flexible dieting” (IIFYM – If It Fits Your Macros) with structured nutrient ratios. The community consensus on Reddit suggests that calculating macros is superior to simple calorie counting because it ensures the body gets the fuel needed for hypertrophy (muscle growth) and hormonal health.

How to Calculate (Example)

Here is how the calculation works for a 30-year-old female, 5’5″, 150 lbs, lightly active:

1. Convert Metrics: 150 lbs = 68 kg; 5’5″ = 165 cm.
2. Calculate BMR: (10 × 68) + (6.25 × 165) – (5 × 30) – 161 ≈ 1,400 calories.
3. Calculate TDEE: 1,400 × 1.375 (Light Activity) = 1,925 calories.
4. Apply Deficit (Loss): 1,925 – 20% = 1,540 calories.
5. Split Macros (40/30/30):
   Protein: (1540 × 0.40) / 4 = 154g
   Fats: (1540 × 0.30) / 9 = 51g
   Carbs: (1540 × 0.30) / 4 = 115g

Frequently Asked Questions (FAQ)

Is this calculator accurate for everyone?
While highly effective, all calculators are estimates. Reddit users recommend tracking your weight for 2 weeks and adjusting calories by +/- 100 if weight stalls.

Why is the protein setting so high?
The Katy Hearn method prioritizes protein to prevent muscle loss while in a calorie deficit. 40% protein is a standard starting point for resistance training.

Should I eat back exercise calories?
Generally, no. The “Activity Level” multiplier already accounts for your exercise. Adding them back often leads to overeating.

How do I adjust for maintenance?
Select “Maintain Current Weight” in the Goal dropdown. This removes the 20% caloric deficit but keeps the macro ratios optimized for body composition.