Overweight, obesity and type 2 diabetes (T2D) are currently the most serious and challenging health problems. Engaging in sufficient levels of physical activity (PA) and limiting sitting(sedentary) behaviour (SB) can help in reducing the prevalence of overweight, obesity and T2D. Evidence has shown that family-based lifestyle interventions are effective in improving health behaviours of both children and parents. However, it is often seen that only mothers are engaged in these family-based interventions, and that fathers are severely underrepresented and difficult to engage. Therefore, there is an urgent need for effective lifestyle interventions in which the father is actively engaged together with their child(ren) in order to prevent overweight, obesity
and T2D in the family. The current project proposes an effective lifestyle intervention for fathers and their children, which is unique and innovative because (1) it is theory-based (i.e. framed within the Self-Determination Theory and the Family System Theory) and (2) it focuses not only on improving PA but also on reducing SB, a behaviour that is independently related to overweight, obesity and T2D but often not targeted in lifestyle interventions. As multi component interventions appear to be more effective in achieving long-term effects, our intervention will include real-life father-child sessions in which mutual activities for father and child are emphasized, next to a Mobile Health Application (“mHealth app”).