RESUMEN
This study explored whether altruistic behaviour would decrease agent's unhealthy food intake, and whether vitality and state self-control would sequentially mediate this effect based on the Self-Determination Theory Model of Vitality. It included 1019 college students in total across three studies. Study 1 was a laboratory experiment. By framing a physical task as a helping behaviour or a neutral experimental task, we examined whether these framed tasks impacted participants' subsequent unhealthy food intake levels. Study 2 was an online investigation measuring the relationship between donation (vs. no donation) behaviour and participant's estimated unhealthy food intake level. Study 3 was an online experiment with a mediation test. By random assignment of conducting a donation behaviour versus a neutral task, we examined whether these behaviours affected participants' vitality, state self-control, and estimated unhealthy food intake levels. In addition, we tested a sequential mediation model with vitality and state self-control as the mediators. Both unhealthy and healthy foods were included in Study 2 and 3. Results showed that altruistic behaviour could decrease agent's unhealthy (but not healthy) food intake, and this effect was sequentially mediated by vitality and state self-control. The findings highlight that altruistic acts may buffer agents against unhealthy eating behaviour.