Increase in plasma pollutant levels in response to weight loss is associated with the reduction of fasting insulin levels in men but not in women

Abstract Environmental pollutants can act as endocrine modulators. In this study, we examined whether weight loss-induced changes in plasma organochlorine compounds (OC) were associated with those in plasma insulin levels. Fasting insulin and the area under the curve (AUC) of insulin after a 75-g oral glucose load, plasma levels of 1 commercial polychlorinated biphenyl (PCB) mixture (Aroclor 1260), 1 PCB congener (PCB 153), and 3 pesticides (2,2'-bis(4-chlorophenyl)-1,1-dichloroethylene ( p,p' -DDE), beta-hexachlorocyclohexane ([beta ]-HCH), and hexachlorobenzene (HCB)) were measured before and after a 15-week weight loss program induced by a caloric restriction in a sample of obese men and women. Both genders showed a similar reduction in body weight ([ap ] 11 kg) in response to treatment, although men lost significantly more fat mass than women (mean [plusmn] SD 9.4 [plusmn] 4.1 v 5.9 [plusmn] 5 kg, respectively, P [lt ] .05). Fasting insulin and AUC of insulin significantly decreased in men and women after the treatment. In response to weight loss, a significant increase in OC was observed in both genders, and this effect was more pronounced in men. The greater the increase in plasma OC levels, the greater the reduction in fasting insulin was in response to weight loss in men ([minus ].49 [lt ] r [lt ] [minus ].59, P [lt ] .05), but not in women ([minus ].22 [lt ] r [lt ] .01, not significant [NS]). In both genders, no relationship was observed between changes in plasma OC levels and changes in AUC of insulin ([minus ].41 [lt ] r [lt ] [minus ].08, NS). In men, relationships between changes in plasma HCB, Aroclor 1260, and PCB-153 concentrations and those in fasting insulin levels in response to weight loss remained significantly correlated after correction for fat mass loss ([minus ].46 [lt ] partial r [lt ] [minus ].51, P values ranging from .05 to .07). These results suggest that weight loss-induced increase in plasma pollutant levels tends to be independently associated with the reduction of fasting insulin levels in men, but not in women. Further studies are needed to verify whether these findings are causally related.