Body Metrics Calculator (9-in-1 Metabolic Hub)

Why Unified Body Metrics Matter

Managing health, physical fitness, and body composition requires understanding multiple metabolic metrics. Rather than entering your height, weight, age, gender, and activity level across ten different individual pages, entering your core body statistics once unlocks a complete 360° metabolic profile across 9 distinct specialized tabs.

The 9 Pillars of Metabolic Profile

• BMR (Basal Metabolic Rate): The baseline calories your body consumes at rest to maintain cardiac, respiratory, and cellular life functions. Calculated using the clinically validated Mifflin-St Jeor formula.
• TDEE (Total Daily Energy Expenditure): Your complete daily caloric expenditure combining BMR with your daily physical movement and exercise multiplier.
• Body Fat %: Estimated using the official U.S. Navy Circumference Method (neck, waist, and hip circumferences relative to height).
• Ideal Body Weight: Healthy target weight ranges based on WHO BMI cutoffs (18.5 – 24.9) and Dr. B.J. Devine's clinical formula.
• Lean Body Mass (LBM): Total body mass minus adipose fat mass, reflecting muscle tissue, bone density, and organ weight.
• Macro Split (Carbs, Protein, Fats): Customized macronutrient distribution matched to your caloric goal (Fat Loss, Maintenance, or Muscle Gain).
• Protein Target: Optimal daily protein intake (g/kg body weight) tailored to activity level and muscle synthesis goals.
• Daily Water Intake: Hydration baseline computed from body mass, workout duration, and climate factors.
• Calorie Deficit Calculator: Target daily intake to achieve safe fat loss rates (e.g., 0.5 kg/week) with timeline estimates.

Formula & Calculation Methodology

The core BMR equation (Mifflin-St Jeor):

Where S is +5 for males and -161 for females.

TDEE is then calculated by multiplying BMR by your Activity Factor (1.2 for Sedentary up to 1.9 for Extra Active).

Worked Examples per Mode

• BMR & TDEE: 28-year-old male, 175 cm, 72 kg, Moderately Active (1.55 multiplier) → BMR = 1,675 kcal/day | TDEE = 2,596 kcal/day.
• Body Fat % (U.S. Navy): Neck 38 cm, Waist 82 cm, Height 175 cm → Estimated Body Fat = 16.5% | Lean Mass = 60.1 kg.
• Calorie Deficit: To lose 0.5 kg of fat per week (requires ~3,850 kcal weekly deficit), consume 2,046 kcal/day (550 kcal below TDEE).