Outcome-driven studies designed to evaluate potential effects of games and apps designed to promote healthy eating and exercising remain limited either targeting design or usability factors while omitting out health-based outcomes altogether, or tend to be too narrowly focuses on behavioral outcomes within a short periods of time thereby less likely to influence longitudinal factors that can help sustain healthy habits. In this paper we argue for a unified approach to tackle behavioral change through focusing on both health outcomes and cognitive precursors, such as players' attitudes and behaviors around healthy eating and exercising, motivation stage and knowledge and awareness about nutrition or physical activity. Key findings from a 3-month long game play study, with 47 female participants indicate that there are clear shifts in players' perceptions about health and knowledge about eating. This paper extends our current understandings about approaches for evaluating health games and presents a unified approach to assess effectiveness of game-based health interventions through combining health-based outcomes and shifts in players' cognitive precursors.