Background: A fad diet is a broad term used to describe dieting methods that recommend altering the intake of macronutrients to specific proportions or instruct people to intake or avoid particular foods, often with the goal of rapid weight loss. Previous literature reviews report social influence impacts general diet behaviour, but have yet to examine fad diets, specifically. Therefore, the purpose of this systematic review was to synthesize literature related to social influence on an individual's fad diet use and understand the sociocultural factors related to diet use. Methods: Using PRISMA guidelines, Medline, PsycInfo, Embase, CINAHL, and CENTRAL databases were searched to identify articles investigating the impact of social on fad diet use. Covidence was used to manage the review process and Garrard's Matrix Method was used to extract data from reviewed articles (n = 13). Results: A majority of reviewed studies examined interpersonal influence (62%) and reported social influence impacting a variety of fad diet behaviours (92%). Interpersonal and media influence were highlighted as motivating factors for adopting unhealthy dieting methods (54%), and studies showed interpersonal support impacted adoption and maintenance of fad diet use (23%). Also, social norms were reported to influence unhealthy weight control behaviours (15%). Discussion: This review revealed social influence is associated with the adoption, adherence, and termination of fad diets. The prevalence of fad diets in society and the lack of research on this topic warrants further examination of factors related to fad diets use and the spread among interpersonal networks.
Keywords: diet behaviour; popular diets; social influence.