South Asians in the US face a pressing chronic disease crisis, with concerns of limited dietary knowledge and self-efficacy among young adults. Health education interventions are crucial to reduce disease prevalence and improve overall health. However, there are limitations in contemporary health education interventions, primarily in terms of affordability and accessibility. This study evaluates a novel chatbot micro-intervention aimed at the dietary behaviors of South Asian young adults. To develop the lesson content, formative research was conducted to characterize the diet of South Asian young adults and identify the key influences in their dietary behaviors. Areas of concern related to dietary attitudes and self-efficacy emerged from these findings, which were mapped out using the Theory of Planned Behavior (TPB) and used to construct lessons. The lesson content was translated into interactive chatbot texts; participants completed a pre-intervention survey to determine which lesson was relevant to their needs. An Instagram and Facebook-based chatbot was used to provide lessons. The impact was assessed using a pre-post knowledge and self-efficacy questionnaire based on the TPB. Paired t-tests were conducted to compare participants' pre and post-lesson and behavioral intention scores, and mixed-effects linear regression was conducted while accounting for individual-level variations. The analysis was conducted using a longitudinal design, with pre and post-intervention data collected from 116 participants. At baseline, participants born in the USA had lower dietary behavior intention scores (-1.79, [-3.24, -0.35], p< 0.05) than those born outside the USA. There was an approximately even split between participants who used Facebook (n=60) and Instagram (n=56) to participate in the intervention. Post-intervention, participants reported an overall improvement in dietary knowledge and self-efficacy (p< .001, mean difference: 1.04, 95% CI: [0.80, 1.28]) and greater intention to practice a healthy diet (p<.001, 0.58 [0.31, 0.86]). Analysis revealed significant improvements in participants' dietary knowledge and self-efficacy scores after engaging with a chatbot tailored to the needs of South Asian young adults. Insights from this analysis identify pathways to further improve social media chatbot micro-interventions to enhance engagement, impact, and feasibility, paving the way for further scaled-up interventional assessments.