**Background:** Young people in out-of-home care (OOHC) experience higher rates of poor physical and mental health, including obesity, compared to their peers. In Australia, 7% of young people in OOHC reside in residential care settings. Despite high rates of overweight/obesity (62.8% in an earlier Australian study by Cox et al., 2014), there was a paucity of interventions targeting healthy lifestyles in this population. The HEALing Matters program was developed and scaled up to address this gap.
**Methods:** The paper describes a multi-phase journey: (1) formative research (2011–2016) including a systematic review, cross-sectional studies, and a randomised trial of the earlier 'HEAL' program in 48 residential homes; (2) co-design workshops with 20 key stakeholders and a participatory approach including two young people with lived experience employed as research assistants; (3) state-wide implementation guided by the National Implementation Research Network's (NIRN) Active Implementation Formula, mapped to Exploration, Installation, Initial Implementation, and Full Implementation stages. Data sources included baseline surveys (n = 613 carers from 12 Community Service Organisations), post-training surveys (n = 463), matched pre-post surveys (n = 421), and semi-structured interviews (n = 27 carers from 6 organisations). Quantitative outcomes were assessed using Wilcoxon signed-rank tests. Qualitative free-text responses (n = 363) were analysed using inductive content analysis.
**Key Results:** At baseline, only 23.0% of carers reported their organisation offered training to improve health literacy, and 49.9% felt they could easily access information to support healthy lifestyles. Most carers (62.6%) strongly agreed or agreed there was a strong need for HEALing Matters. Post-training, 70.2% of carers agreed that delivering HEALing Matters is part of their role. Statistically significant improvements were found for: knowledge to contribute to health and well-being of young people (Z = 4.648, p < 0.001); understanding of Australian Dietary Guidelines (Z = 7.942, p < 0.001); application of Dietary Guidelines (Z = 7.969, p < 0.001); understanding of Physical Activity Guidelines (Z = 9.513, p < 0.001); application of Physical Activity Guidelines (Z = 9.417, p < 0.001); and knowledge of trauma-informed care (Z = 3.488, p < 0.001). Over 75% of carers agreed they had the knowledge, skills, and motivation to implement the program, though confidence was lower when young people were unmotivated. 85% of Community Service Organisations in Victoria agreed to implement HEALing Matters, with 50% considered 'highly engaged'. Over 1300 carers registered, and 501 completed the training. Booster grants ($250 per worker, up to $1000 per home) were used to purchase physical activity equipment, gardening supplies, and cooking utensils.
**Clinical Implications:** HEALing Matters addresses a critical gap in training and support for residential carers to promote healthy lifestyles among vulnerable young people. The program has moved beyond a purely behavioural approach to one informed by attachment, trauma, and resilience theories, recognising that food and physical activity can demonstrate trust and care. The co-design process and use of the NIRN framework provide a model for implementing complex health interventions in challenging, real-world settings. Ongoing evaluation and attention to organisational barriers (e.g., competing priorities, staff shortages, need for dedicated training time) will be essential for sustainability and full integration into routine practice.