The main section (Section 2) provides an account of the available knowledge concerning health effects, and the corresponding impacts on healthcare costs, of the following health-related behaviours/conditions: smoking, alcohol consumption, obesity, nutritional choices and physical activity. In Section 3, I go through the available evidence regarding the effectiveness and cost effectiveness of public policies constructed in order to modify health behaviours (primary and secondary prevention) and to reduce weight. The paper ends by a summary' of the findings and an identification of important issues and challenges for future research. Performing systematic reviews of the evidence published in the different research areas spanned is considered to be beyond the scope of this study.