We study how people select their health support ties from their broader personal networks, taking into account the interplay of web-based and face-to-face interactions. We focus on users of self-styled Internet communities on eating disorders, often dubbed 'pro-ana' and 'pro-mia' and widely feared to contribute to maintaining and spreading these disorders. Despite the controversial antimedical stances of some of them, ‘ana-mia’ websites may channel mutual assistance, advice, and psychological and emotional support, with ultimate benefits for health. In 2011-12 we fielded an online survey of users of French- and English-language ‘ana-mia’ websites, mapping the composition and structure of their personal networks both online and face-to-face, and their health and eating-related support networks, for two types of health issues. We estimate binary choice models for these data and find that different health needs call for different types of support, embedded in different parts of personal networks. Specifically, online groups provide distinctive sources of help, which partly compensate for perceived shortcomings in healthcare services, although members do not overwhelmingly reject standard health systems and norms. We discuss how web-based groups constitute an important source of social support, and a potential resource for enhanced public health services provision.