Body composition determines direct FFA storage pattern in overweight women

Area of Science:

• Metabolic Physiology
• Obesity Research
• Adipose Tissue Biology

Background:

• Direct free fatty acid (FFA) storage in adipose tissue is a key pathway for postabsorptive lipid storage.
• Understanding how body fat distribution influences this process is crucial for comprehending obesity phenotypes.

Purpose of the Study:

• To investigate the effect of different obesity phenotypes (upper body vs. lower body) on direct FFA storage in women.
• To examine the relationship between FFA storage and very-low-density lipoprotein-triglyceride (VLDL-TG) storage in adipose tissue.

Main Methods:

• Recruited 28 women: 10 upper body overweight/obese (UBO), 11 lower body overweight/obese (LBO), and 7 lean.
• Administered intravenous tracers ([9,10-(3)H]palmitate and [1-(14)C]triolein-labeled VLDL).
• Performed upper and lower body subcutaneous fat biopsies and assessed regional fat mass using DEXA and CT scans.

Main Results:

• UBO women showed significantly greater fractional FFA storage in upper body subcutaneous (UBSQ) fat compared to lean women.
• LBO women exhibited higher FFA storage per adipocyte in lower body subcutaneous (LBSQ) fat compared to UBSQ fat.
• Fractional FFA storage was positively correlated with fractional VLDL-TG storage in both UBSQ and LBSQ adipose tissue.

Conclusions:

• Upper body obesity is associated with increased FFA storage in the upper body depot.
• Lower body obese women demonstrate more efficient FFA storage in lower body adipocytes, potentially influencing their body fat distribution.
• Direct FFA storage and VLDL-TG fatty acid storage appear to share a common rate-limiting pathway in adipose tissue.