influence of sex and obesity phenotype on meal fatty acid metabolism before and after weight loss

BACKGROUND: Regional differences in meal fat storage may explain the preservation of fat accumulation in obese persons. OBJECTIVE: The objective was to determine whether meal fatty acid (FA) metabolism differs by sex and obesity phenotypes before and after weight loss. DESIGN: A [³H]triolein-containing meal was given to trace meal FA oxidation (³H₂O generation) and adipose tissue uptake (abdominal subcutaneous and gluteal biopsy samples) in 13 upper-body obese (UOb) men, 9 UOb women, and 8 lower-body obese (LOb) women (study 1). Dual-energy X-ray absorptiometry and abdominal computed tomography were used to measure fat distribution. The subjects participated in a diet and exercise weight-loss program, after which 23 subjects returned for an identical study (study 2). RESULTS: In study 1, the storage of meal FA (mg meal fat/g adipose lipid) was greater in gluteal than in abdominal fat (P = 0.022) in LOb women, but not in UOb women or UOb men. UOb men stored a lesser percentage of meal FAs in both upper- and lower-body subcutaneous fat than did the LOb and UOb women (P = 0.001 and P = 0.044, respectively). The participants who returned for study 2 had lost 14.1 ± 1.1 kg. Changes in the uptake of meal FAs followed a pattern indicative of obesity phenotype maintenance by group. The uptake of meal FAs increased in upper-body subcutaneous fat (P = 0.028) in weight-reduced UOb women and UOb men (P = 0.046) and decreased in lower-body fat (P = 0.025) in UOb men. CONCLUSION: The differences in meal FA trafficking by obesity phenotype suggest that meal FA storage may play a role in regulating body fat distribution in obese persons.