About

Precision in nutrition is the difference between guessing and progressing. Whether you are an athlete optimizing performance, a bodybuilder cutting body fat, or someone simply trying to balance energy levels, understanding your macronutrient split is essential. Calories determine weight change, but macronutrients dictate body composition.

This tool goes beyond simple calorie counting. It integrates seven distinct metabolic formulas to establish a baseline Basal Metabolic Rate (BMR) and adjusts for specific activity levels. By manipulating the protein, fat, and carbohydrate ratios, users can tailor their intake to specific dietary protocols—from balanced USDA recommendations to high-performance athletic splits. This level of customization ensures that the numbers provided align with your physiological reality and lifestyle goals.

Formulas

The core calculation starts with the Mifflin-St Jeor equation, widely considered the most accurate for the general population, though other models like Katch-McArdle are superior for lean individuals. The basic structure for finding Total Daily Energy Expenditure (TDEE) is:

TDEE = BMR × ActivityMultiplier

Once TDEE is established, macronutrients are calculated based on caloric density:

Grams = TDEE × PercentageCalPerGram

Where constants are applied as follows:

1 g Protein = 4 kcal

1 g Carbs = 4 kcal

1 g Fat = 9 kcal

Reference Data

Diet Protocol	Carbs (%)	Protein (%)	Fats (%)	Best For
Balanced (Standard)	45-65%	10-35%	20-35%	General health, maintenance
Zone Diet	40%	30%	30%	Blood sugar control, inflammation
Low Carb	10-25%	40-50%	30-40%	Weight loss, insulin sensitivity
Ketogenic	5-10%	20-25%	70-80%	Deep ketosis, epilepsy management
High Protein (Athlete)	35-45%	35-40%	20-25%	Muscle repair, hypertrophy
High Carb (Endurance)	60-70%	15-20%	15-20%	Marathon runners, triathletes
Carnivore-ish	0-5%	40-50%	45-55%	Elimination diets, autoimmune

Frequently Asked Questions

Each metabolic formula was derived from different population studies. The Harris-Benedict is one of the oldest and tends to over-estimate for modern sedentary lifestyles. Mifflin-St Jeor is currently the gold standard for accuracy in non-obese individuals. Katch-McArdle relies on Lean Body Mass rather than total weight, making it significantly more accurate for athletes with low body fat.

Most people overestimate their activity. 'Sedentary' covers office jobs and light movement. 'Lightly Active' usually implies dedicated exercise 1-3 times a week. If you work a physical job (construction, farming), you are likely 'Active' or 'Very Active' regardless of gym time. It is generally safer to underestimate activity and adjust upwards based on real-world weight trends.

For general health and standard diets, total carbs are sufficient. However, if you are following a specific Low Carb or Keto protocol, tracking Net Carbs (Total Carbs minus Fiber and Sugar Alcohols) is often preferred because fiber does not impact blood sugar or insulin in the same way digestible carbohydrates do.

Absolutely. Protein is essential for repairing tissues, producing enzymes, and supporting immune function. Even sedentary individuals require adequate protein (approx. 0.8g per kg of body weight) to prevent sarcopenia (muscle loss) as they age. Higher intakes are simply required for those actively breaking down muscle tissue through exercise.