Exploring body composition ratios and their relation to cardiometabolic disease risk factors in adults with varying body mass index categories.

INTRODUCTION

Muscle and bone are impacted by adiposity and metabolic dysfunction. To investigate their relationship, we assessed total and regional muscle-to-bone (MBR) and soft tissue-to-bone (SBR) ratios and their association with cardiometabolic risk factors in adults across body mass indexes (BMIs).

METHODOLOGY: This study included 152 males (n=58; age 28.8±6.4 yrs) and females (n=94; age 28.1±6.8 yrs) with different BMIs. Dual X-ray absorptiometry provided lean mass, fat mass, and bone mineral content. ANCOVA with Bonferroni correction assessed ratio differences between BMIs while controlling for age. Linear regression assessed associations between the ratios with insulin, glucose, homeostatic model assessment of insulin resistance (HOMA-IR), triglycerides, total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein, TC:HDL ratio, and blood pressure while controlling for BMI and self-reported exercise status.

RESULTS

Males with obesity (OM) had higher arm and leg, but not total MBR than males with healthy weight (HWM). OM had higher total, arm, and leg SBRs (all p<0.001) than HWM. Females with obesity (OF) had higher total, arm, and leg MBRs and SBRs than healthy weight (HWF) (all p<0.01). Controlling for BMI and exercise status in females, total MBR and SBR positively associated with insulin (MBR: adjusted r2=0.24, p=0.02; SBR: adjusted r2=0.25, p=0.01) and HOMA-IR (MBR: adjusted r2=0.28, p=0.04; SBR: adjusted r2=0.30, p=0.01) while SBR associated with TC:HDL ratio (adjusted r2=0.19, p=0.03). No associations were found between the ratios with cardiometabolic outcomes in males.

CONCLUSIONS

OF had higher total and regional MBRs and SBRs than HWF. OM had higher regional MBRs and all SBRs than HWM, but not total MBR. Total MBR and SBR associated positively with insulin and HOMA-IR in females, but not males. In females, SBR also positively associated with TC:HDL ratio. Although higher MBRs and SBRs may relate to higher cardiometabolic risk in females, further research is needed.