Endocrine-disrupting polychlorinated biphenyls in metabolically healthy and unhealthy obese subjects before and after weight loss: difference at the start but not at the finish.

BACKGROUND: A subset of obese individuals does not exhibit metabolically unfavorable features; this group is referred to as metabolically healthy obese (MHO). Serum concentrations of polychlorinated biphenyls (PCBs), which are chemicals with endocrine-disrupting properties, have been shown to be lower in MHO than in metabolically unhealthy obese (MUO).

OBJECTIVE: We studied PCB serum concentrations during and after weight loss and their relation with metabolic health.

DESIGN: We determined metabolic health features (weight, blood pressure, lipids, inflammation, and glucose metabolism) and serum PCB concentrations of 27 PCBs in a cohort of 184 overweight and obese subjects. Metabolic health was evaluated with the use of the criteria of the metabolic syndrome (MetS) [metabolic syndrome according to Adult Treatment Panel III criteria present (MetS+) or metabolic syndrome according to Adult Treatment Panel III criteria absent (MetS−)] or with extended criteria with inflammation and insulin resistance taken into account (MUO compared with MHO). Participants were treated with lifestyle counseling or bariatric surgery. A metabolic and toxicological re-evaluation was performed after 6 and 12 mo.

RESULTS: At baseline, serum ΣPCB concentrations were significantly higher in MUO than in MHO (ΣPCBs: 138 ±105 compared with 365 ± 481 ng/g lipid weight; P = 0.01) but not in MetS+ compared with MetS− subjects. No difference was detected in the percentage increase in PCB serum concentrations in MetS+ compared with MetS− subjects (median: 58% compared with 43% and 31% compared with 69% at 6 and 12 mo, respectively). The comparison of persistent with resolved MetS and MUO did not reveal any difference in ΣPCB concentration increments (median: 49% compared with 58% at 12 mo for MUO; P > 0.05). In a regression model with age, smoking, and body mass index corrected for, PCB serum concentrations at baseline were not predictive of the persistence or resolution of a metabolically unfavorable state.

CONCLUSION: Our study indicates that the increment in serum concentrations of PCBs does not differ according to metabolic health and does not seem to influence the beneficial metabolic health effects of weight loss. This study was registered at clinicaltrials.gov at NCT01778868.