It's more complicated than you might think:
According to the WHO's data gathering protocol, we should use a stretch-resistant tape to measure the waist circumference at the midpoint between the last palpable rib and the top of the iliac crest.
Hip circumference should be measured around the widest portion of the buttocks, with the tape parallel to the floor.
Practically, the measurements are usually taken at the smallest circumference of the natural waist, usually just above the belly button and the widest part of the buttocks or hip.
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