Body fat percentage and sacral-abdominal wall distance are associated with obesity in patients with osteoporosis: a retrospective study.

Obesity assessment in patients with osteoporosis is challenging because spinal deformities and height loss may distort body mass index (BMI)-based classifications. This retrospective cross-sectional study investigated the associations between obesity and two body composition-related indices: the android/gynoid fat ratio (A/G ratio) derived from dual-energy X-ray absorptiometry and the sacral-abdominal wall distance (SAD) measured on standing lateral spine radiographs. A total of 385 women with osteoporosis were included. Obesity was defined using two criteria: BMI ≥ 25 kg/m2 and BMI ≥ 25 kg/m2 or body fat percentage ≥  35%. Higher A/G ratio and greater SAD were independently associated with obesity under both definitions after adjustment for potential confounders. When a combined criterion incorporating both A/G ratio and SAD was applied, the strength of the association with obesity was greater than that observed when either parameter was considered alone in multivariable models. These findings were consistent across the two obesity definitions. The combined use of A/G ratio and SAD may be useful for characterizing obesity-related body composition in women with osteoporosis, particularly in clinical settings where BMI-based assessment is limited by spinal deformity. Given the cross-sectional design, these associations should not be interpreted as causal, and further longitudinal studies are warranted.