Abstract Background The World Health Organization describes obesity as one of the greatest public health challenges in the 21st century. Possible therapies include multimodal (group) programmes with nutrition, exercise, and behavioural therapy elements. However, programme providers often have difficulties recruiting the target groups and motivating them to participate. This systematic review aimed to identify barriers and facilitators as well as strategies to improve recruitment. Methods We systematically searched five databases (Medline, CINAHL, Cochrane, PsycInfo, Web of Science). Based on predefined inclusion criteria, we selected primary studies of different study designs (e.g. [randomised] controlled trials, qualitative studies). We extracted barriers and facilitators as well as recruitment strategies into predefined tables, assessed the quality of the studies and summarised the results narratively. Results Of the 1,082 articles identified, 16 met the inclusion criteria. The main active recruitment strategies were writing directly to potential participants and referrals from health professionals. The most frequently reported passive strategies included media adverts, websites, flyers, social media, and word of mouth. The information on how many people approached actually participated was heterogeneous, which illustrates that recruitment depends on the setting/context and the people involved. Some studies came to contradictory results, e.g., regarding whether passive or active methods are more successful. In most cases, a combination of strategies was recommended. The studies reported numerous recruitment barriers, e.g., lack of staff time, lack of motivation, or fear of discrimination. Conclusions The review provides a broad overview of recruitment methods that can be applied depending on the framework conditions and target groups. The summary of possible barriers can serve as an overview of which aspects could be considered when designing or adapting a programme. Key messages • To improve recruitment to obesity programmes, a combination of several recruitment strategies, including active and passive methods, should be applied. • Results on the “effectiveness” of the strategies were inconclusive, which indicates that the success of methods depends on the context, setting and the people involved.
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