Health & Fitness · 理想体重（Ideal Weight） · Updated 2026-10-25
What Is Ideal Weight?
Definition
The classic modified Broca formula: men height−105, women (height−105)×0.95 — memorable but averages away frame differences. The scientific version back-solves from BMI: ideal range = height²(m²)×[18.5, 23.9]. At 170cm that is 53.5-69.1 kg — a 15.6 kg band, because "ideal weight" is a range, not a number. Frame (wrist circumference), muscle mass and age shift the optimum within it: in older adults, sitting slightly above the band midpoint is associated with lower mortality (the obesity paradox at the mild end).
Formula
Ideal range = height²(m²) × [18.5, 23.9]
Worked Example
A 165cm woman: Broca says 57kg; the BMI band is 50.4-65.1 kg. At 58kg with 26% body fat she sits upper-band — recomposition beats further weight loss.
Common Misconception
"You must hit height−105" — the formula is a 19th-century rough cut, and chasing a single number invites extreme dieting. "Thinner is better in old age" is wrong too: ages 65+ show the lowest mortality at BMI 22-26.9, and deliberate weight loss sacrificing muscle presages disability.
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