Why Two People With the Same BMI Can Have Very Different Health Risk
Two people can share an identical BMI while carrying meaningfully different health risk because BMI only accounts for total weight relative to height, not where that weight is distributed on the body — one person might carry proportionally more fat around the abdomen (a body shape often described as "apple-shaped"), while the other carries more around the hips and thighs ("pear-shaped"), and research has associated the former pattern with meaningfully higher cardiometabolic risk at the same overall weight.
This is one of the clearest, most concrete illustrations of why a single number like BMI has real, documented limitations as a standalone health measure.
The apple vs. pear shape distinction
An "apple" body shape (more fat around the midsection) and a "pear" body shape (more fat around the hips and thighs) can occur at the exact same BMI, since BMI has no way to distinguish between them — waist-to-hip ratio is specifically designed to capture this difference that BMI structurally can't see.
Why this gap matters practically
For someone whose BMI alone suggests a lower health risk than a waist-to-hip ratio measurement does, the ratio result adds genuinely useful additional information — this is exactly the situation where checking both measures together, as covered in the WHR-beyond-BMI guide, gives a more complete picture than either alone.