The aim of this study was to investigate the variations in the plasma levels of the soluble tumour necrosis factor receptor type-I (sTNFR-I) and type-II (sTNFR-II) during weight loss which was induced by 3 weeks on a very low calorie diet (3.9+/-0.1 MJ/day), in 17 non-diabetic obese women. Plasma sTNFR-I concentrations decreased significantly after weight loss (p < 0.05), but there was no significant change in plasma sTNFR-II. As the diet was associated with a significant decrease in body fat mass (=2.5 kg), this result supports the emerging concept that adipose tissue can produce significant amounts of sTNFR-I and that this production can be modified by weight loss in human obesity.