Many implementation barriers relate to lifestyle interventions (LIs) being developed by scientists. Exploring whether implementation of non-evaluated LIs is less complicated, might offer insight how to improve the use of effective interventions. This study aimed to identify influencing factors for implementation and compare factors between evidence supported and non-evaluated LIs. Evidence-supported (n = 7) and non-evaluated LIs (n = 7) in hospitals, general practices and community care organizations were included as cases. Semi-structured interviews (n = 46) were conducted. Additionally, documents (n = 207) were collected describing intervention, implementation process, and policy. We used a stepwise approach to inductively identify factors, organize them by diffusion phase, and an existing framework. A total of 37 factors were identified. "Dissemination" factors were mainly observed in evidence-supported LIs. "Compatibility to existing structures" ("adoption"), "funding" and "connection to existing care processes" ("implementation") was factors identified in all cases. "Quality control" and "ongoing innovation" ("maintenance") were reported in evidence-supported interventions. In all domains of the framework factors were observed. Factors identified in this study are in line with the literature. The findings do not support the assumption that implementation of non-evaluated LIs is perceived as less complex.