Body weight loss increases plasma and adipose tissue concentrations of potentially toxic pollutants in obese individuals

BACKGROUND: While there appears to be a consensus among scientists and clin icians that body weight loss reduces the risk of several chronic diseases, these apparently favourable effects should be balanced against any potentia lly harmful side effect of weight loss. In this regard, weight loss has bee n shown to produce an increase in blood concentration of potentially toxic organochlorine pollutants in animals that can cause prejudice to health, bu t human data are lacking. METHODS: Thirty-nine obese individuals were subjected to a hypocaloric diet during 15 weeks, Blood and subcutaneous adipose tissue samples were analys ed before and after treatment for 26 organochlorine compounds. A control gr oup consisting of 57 women of similar mean age was also formed in order to compare plasma concentrations. RESULTS: Organochlorine pollutants were found in every subject and all 19 c ompounds detected had their plasma concentration increased following treatm ent (mean body weight loss 9.5 kg). 15 of which were statistically signific ant. When compared with a control group, five compounds increased significa ntly. These observations persisted after an 18 week low-fat diet/exercise p rogram follow-up. Increases were correlated with body weight loss (-0.3 gre ater than or equal to r greater than or equal to -0.6, P < 0.05) and adipos e tissue analyses yielded similar results, as their concentration of organo chlorine compounds increased following treatment. CONCLUSION: Body weight loss increases plasma and subcutaneous adipose tiss ue concentrations of organochlorine pesticides and PCBs in obese subjects. These results raise concerns about an undesired and potentially harmful sid e effect of weight loss in some obese patients who seem to be at greater ri sk of health problems than leaner subjects since they show higher organochl orine body burden.