Fitness center activities have gained popularity. One central role fitness staff members have is to help participants to become or maintain health and fitness. In recent years, a new phenomenon – orthorexia nervosa, which M.D. Bratman coined in the late 1990s – has emerged. He termed orthorexia as "a fixation on eating healthy food". Research has mentioned that participants in sports and fitness activities may be at higher risk of becoming orthorexic. Since the late 1990s, orthorexia has been noticed, also in Swedish newspaper articles. In so doing, the 'condition' has evolved to include fanatic exercise and eating behaviours. Fitness professionals might thus work with individuals that are considered to suffering from orthorexia. The purpose of this presentation is to elucidate and problematize ethical issues that are raised during the research that deals with personal trainers and group fitness instructors talk of health and orthorexia. The material will consist of four focus groups with 18 fitness professionals that work in Swedish fitness centers. It will be carried out as a qualitative study. This study raises ethical issues, including for instance: a) by focusing and giving attention to orthorexia, the study may contribute to categorizing "the problem", as well as enlarge it. This paradoxical situation as the aim is to contribute scientific knowledge that can problematize orthorexia; b) the challenge to manage and balance a critical approach without causing harm (e.g. introduce orthorexia to fitness professionals who might have an erroneous perspective of and/or have little knowledge about orthorexia) (cf. Halse & Honey, 2005).