How 'Ideal Weight' Formulas Actually Work, and Their Real Limits
Common ideal weight formulas (such as the Devine or Robinson formulas) estimate a target weight based primarily on height and sex, generally developed originally for medical dosing calculations rather than as a personal health target — they don't account for muscle mass, frame size, or individual body composition, which is why they should be treated as a rough reference range, not a precise personal goal.
These formulas have an interesting origin that explains their real limitations — understanding where they came from clarifies how to actually use the number they produce.
Where these formulas actually came from
Several commonly cited "ideal weight" formulas were originally developed for medical purposes like calculating appropriate medication dosages, not as a personal health or fitness benchmark — this origin explains why they're based on simple height-and-sex inputs rather than a fuller picture of body composition.
What they don't account for
These formulas don't distinguish muscle mass from fat mass, don't account for frame size (naturally larger- or smaller-boned individuals), and don't reflect individual body composition goals — the same limitation BMI has, covered in more detail in the BMI guide, applies here for largely the same underlying reason.
How to use the result appropriately
Treating the output as a rough reference range rather than a precise personal target, and considering it alongside other measures (body fat percentage, how clothes fit, overall fitness and energy levels) gives a much more complete and personally meaningful picture than a single height-based number in isolation.