Weight Loss Needed to Reduce BMI from 31.4 to 25: Calculation Guide

Formula

BMI = weight (kg) ÷ height (m)² → weight (kg) = BMI × height (m)²

Example Calculation (Height = 1.70 m)

• Current weight at BMI 31.4: 31.4 × 1.70² = 90.8 kg.
• Target weight at BMI 25: 25 × 1.70² = 72.3 kg.
• Weight to lose: 90.8 – 72.3 = 18.5 kg (≈41 lb).

General Formula

Weight loss (kg) = (Current BMI – Target BMI) × Height (m)²

Important Caveats

• Height must be your actual measured height—the 1.70 m example is illustrative only.
• BMI does not distinguish fat vs. muscle; body composition analysis (DEXA, BIA) is superior for setting individualized goals.
• Safe weight loss: 0.5–1 kg/week via 500–1000 kcal/day deficit + resistance training to preserve lean mass.
• Consult a clinician/dietitian before embarking on significant weight loss.