Chapter 01 · The range
Why a range beats a single number
There is no one ideal weight. A healthier way to think about it is a range. The headline figure here is the weight span that corresponds to a body mass index of 18.5 to 24.9 for your height, the band the World Health Organization classifies as a healthy weight for most adults.1 Anywhere in that band is generally considered healthy; where you sit within it is individual.
The second figure is a reference body weight from the Devine formula, a clinical estimate first used for medication dosing, adjusted up or down by about 10 percent for frame size.2 It is a single reference point, not a target you must hit. Frame size is a rough self-estimate, so treat that adjustment loosely.
| Figure | What it is | How to use it |
|---|---|---|
| Healthy range | Weights at BMI 18.5 to 24.9 | A broad, evidence-based band |
| Reference weight | Devine formula, frame-adjusted | One point inside or near the band |
| Frame size | Small, medium, or large build | Nudges the reference, not the range |
BMI does not measure muscle or fat directly; a clinician interprets it with your history.
Chapter 02 · The fine print
What BMI cannot tell you
BMI is a screening tool, not a diagnosis or a measure of health. It does not account for muscle, bone density, or where you carry weight, so a very muscular person can read as overweight while someone within the band can still have metabolic concerns. Waist measurement, blood pressure, blood sugar, and your history matter alongside the number. A clinician puts these together; the calculator cannot.
Use the range as orientation, not a verdict. If you want to change your weight, a clinician can help you set a goal that fits your body and your health. Individual results vary.
