How the numbers are worked out

• BMI = weight (kg) ÷ height (m)². Ranges are the WHO adult ranges: under 18.5, 18.5–24.9, 25–29.9, 30 and over.
• Resting energy uses the Mifflin-St Jeor equation: 10 × weight + 6.25 × height − 5 × age, then + 5 for men or − 161 for women.
• Daily energy use = resting energy × an activity multiplier (1.2 to 1.9).
• The starting target is 500 kcal below daily use to lose weight and 300 kcal above to gain, never below 1,200.

These are population estimates, not measurements, and not medical advice. Pregnancy, illness, medicines and athletic training all change a person's needs.