The CLiMB-Out project aims to detect the risks of becoming obese early-on in children and provide timely interventions to promote a healthier diet and lifestyle. Over 50% of the EU population are overweight or obese. This is known to contribute to the development of chronic metabolic and cardiovascular disorders, which are leading causes of morbidity and mortality worldwide. Child obesity is of particular concern as the number of overweight children has increased tenfold in the last 40 years and, of those, 60% are expected to remain overweigh into adulthood. The CLiMB-Out project is developing predictive tools which are microbiome-informed and help detect the risks of becoming obese, facilitating the implementation of lifestyle and dietary changes early on. This project is also co-designing innovative educational and communication programs to engage families and health care professionals in, and support the adoption of, healthy lifestyles across different socioeconomic environments. This personalised nutrition project will use the latest innovative biotechnologies and artificial intelligence to characterise the microbiome a large cohort of children in southern European countries.