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 (approximately 11 kg) in response to treatment, although men lost significantly more fat mass than women (mean +/- SD 9.4 +/- 4.1 v 5.9 +/- 5 kg, respectively, P <.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 (-.49 < r < -.59, P <.05), but not in women (-.22 < r <.01, not significant [NS]). In both genders, no relationship was observed between changes in plasma OC levels and changes in AUC of
insulin (-.41 < r < -.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 (-.46 < partial r < -.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.