This study is being performed under the European Consortium HealthyW8 that has the main objective of developing a digital tool for personalized recommendations for healthy lifestyle and prevention of obesity. This human study will be a pilot trial that will precede a planned more long-term intervention trial. It will focus on children (age 5 to 12 y) and parents. The main purpose is to study whether the healthy lifestyle recommender solution, reflecting a multi-portfolio intervention and developed within this project, is well accepted by the participants, has a decent adherence (i.e. user time of the app), and whether the overall design is well suited to the participants, in order that they will improve dietary habits. This study will be of longitudinal design without a control group.

At present, numbers of persons with overweight and obesity continue to grow in most countries worldwide. Children and young adults are at risk for different reasons: in the case of children, dietary habits and lifestyle is starting to be developed and if, at this phase, children do not acquire healthy habits, it will be probable that they will have a higher potential to develop obesity and the associated co-morbidities. It is at this stage that food preferences develop. Moreover, children obesity is increasing and it is known that an obese or pre-obese children will have a higher propensity to be an obese adult. For young adults, the risks and concerns are different. Is in this period of life that most people starts an independent life, and consequently decide their food and lifestyle choices, with an increase in irregularity of meals and unhealthy food choices, together with changes in physical activity habits and social or individual pressures. It is essential to give them tools that will allow them to make healthy choices and to have healthy habits, since they will be the future adult population that will raise and inspire the next generation. As solutions to combat the trend toward increasing overweight and obesity are much in need, the present study aims to intervene with the developed healthy lifestyle recommender solution to address various factors known to constitute a risk for developing obesity, including socio-demographic aspects, psychological/behavioural ones, physical activity, dietary patterns, among other. Such a multi-dimensional portfolio approach is believed to be very much needed for the prevention of obesity and co-morbidities, and the personalization of the solution, as well as the nudging/gamification aspects will strive to ensure a high long-term adherence to the developed solution.

The primary objective of the study is to determine whether the developed healthy-lifestyle recommender solution can be successfully applied to the target population (children and their parents), and whether they adhere to using it frequently during the duration of the study.

This will be assessed by adherence time to the lifestyle recommender solution and questionnaires addressing the user-friendliness and limitation or problems encountered. Secondly, the investigators will study whether the assessment of endpoints required for the ensuing long-term study can be well assessed within the study and if despite the limited time of the intervention duration, the intervention will be able to improve some markers related to the risk of obesity and associated co-morbidities.

Inclusion Criteria:

• Children (age 5-12 y) and, at least, one of their parents
• To reside in Portugal (for logistic reasons)
• To be overweight (BMI percentile > 85%)
• Both boys and girls

Exclusion Criteria:

• To have manifest chronic diseases (e.g. cancer)
• To be already in energy restriction or following a specific diet (on their own or advised by their physician)
• To have eating behaviour pathologies

Individual data will be not shared. Data will be treated and only treated data will be available. Only the PI of the study will be access to the correspondence between participant identification and codification that will be given to each participant. There is no need of having identification of participants to reach the conclusions about the study.