Estimating body fat without a scale
Body Adiposity Index (BAI) was introduced in a 2011 study as an alternative to BMI for estimating body fat percentage, using a method that deliberately avoids needing a weight measurement at all — just hip circumference and height.
BAI = hip circumference(cm) ÷ height(m)1.5 − 18
The researchers behind BAI were motivated partly by the practical reality that reliable scales aren't always available, while a tape measure almost always is — making BAI useful in settings like field research or resource-limited clinics.
Mixed evidence on accuracy
Since its introduction, follow-up research comparing BAI against DEXA-measured body fat has produced mixed results — accurate for some populations, less so for others, particularly across different ethnic groups and age ranges. It's best treated as a useful, convenient estimate rather than a definitive measurement.