Fig. 1

Distribution of L3-PSMI (A, B) and L3-PMI (C, D) in young, middle-aged and older Chinese adults by sex and BMI subgroups. Notes: One-way ANOVA with post-hoc Tukey’s test was used to assess the differences between BMI subgroups (normal-weight, overweight, and obese individuals). The p-values for differences between BMI subgroups in post hoc analyses are represented by a (p < 0.05), b (p < 0.01), c (p < 0.0001), and n (p > 0.05). In young and middle-aged adults, obesity was associated with a significantly higher muscle index; however, in older women, the muscle index did not increase in the obese population. PSMI, paraspinal muscle index; PMI, psoas muscle index