Background A population of over 12 000 mature subjects participated in a longitudinal study (8 years) of nutrition and health (the Su.Vi.Max Study). In this context, a specific cross-sectional study was carried out in a randomly selected subpopulation.Aim To identify anthropometric, nutritional and biochemical correlates of spontaneous use of `light' foods and drinks in a free-living population.Design Men (n=2299) and women (n=1979), 45–60 years, reported their food intakes over six non-consecutive days. Consumers of low-fat and low-sugar foods and drinks, and artificial sweeteners, were compared with non-consumers.Results Users of low-sugar products were heavier than non-users; female consumers of low-fat products, but not males, had higher body weight and BMI than non-consumers. Users of low-sugar products had higher triacylglycerols and glycaemia than non-users while biochemical parameters were not different in users and non-users of low-fat products. Use of low-sugar products led to increased diet density of a few micronutrients, including cholesterol. Low-fat product selection was associated with increased intake of most micronutrients, both in absolute value and in density.Conclusions In mature adults, selection of fat-reduced products was associated with improved quality of the diet, while anthropometric and biological parameters appeared less favourable in consumers of low-sugar products vs. non-consumers. The longitudinal follow-up of the cohort in future years will help determine cause-and-effect relationships among these parameters.