The objective of the present study was to investigate whether weight loss is associated with changes in serum concentrations of lutein (L) and zeaxanthin (Z), and/or macular pigment optical density (MPOD). We recruited 104 overweight subjects into this randomised controlled weight loss study. For the intervention group (I group), weight was assessed weekly and body composition, including BMI (kg/m2) and body fat (kg and percentage), was assessed at baseline, 6 and 12 months. Weight loss was encouraged using dietary and exercise programmes. MPOD was measured by heterochromatic flicker photometry and serum concentrations of L and Z by HPLC (at baseline, 1, 3, 6 and 12 months). The control (C) group was assessed at baseline and 12 months. Repeated-measures ANOVA (RMA) demonstrated significant weight loss in the I group over the study period (P = 0·000). There was no significant weight change in the C group (P = 0·993). RMA of dietary L and Z, serum L and Z, and MPOD demonstrated no significant time or time × group interaction effect in any of these parameters (P>0·05 for all), with the exception of a significant decrease in the dietary intake of Z seen in both groups, over the study period (P < 0·05). There was a positive and significant relationship between body fat loss (kg) and increase in serum concentrations of L in the I group (r 0·521; P = 0·006). Our finding that a reduction in body composition (e.g. fat mass) is related to increases in serum concentrations of L is consistent with the hypothesis that body fat acts as a reservoir for this carotenoid, and that weight loss can positively influence circulating carotenoid levels.