The current food environment is characterized by the wide availability of unhealthy products with high sugar, fat and salt content. This constitutes a major barrier for the development of healthy dietary patterns among children and preadolescents. In this context, WP4 "Healthy Food Product Development" will explore children-driven development of nutritionally optimized products, based on the idea that the development of products targeted at children and preadolescents should have an adequate nutrition composition and satisfy their preferences in order to be successful. Research-based guidelines will be developed for the design of gradual sugar reduction strategies applicable to foods targeted at children and preadolescents, as a complement to existing guidelines. The influence of product intrinsic factors (sensory characteristics and nutritional composition) on children's sensory and hedonic perception will be studied, with special emphasis on product reformulation (lowering levels of fat, sugar and salt). In addition, the influence of product extrinsic factors (nutrition labelling, packaging, communication of health messages) on children's and parents product perception and choice will be explored.