title: What everyone else is eating: a systematic review and meta-analysis of the effect of informational eating norms on eating behavior.
abstract: There is interest in the hypothesis that social norms are a determinant of healthy and unhealthy dietary practices. The objective of our work was to assess the weight of evidence that experimentally manipulated information about eating norms influences food intake and choice. This systematic review of experimental studies examined whether providing information about other peoples' eating habits influences food intake or choices. To inform the review, three electronic databases (PsycINFO, MEDLINE, and the Social Sciences Citation Index) were searched during July 2012. A narrative approach was used to synthesize studies that examined the influence of norms on food choice and meta-analyses were used to synthesize the effect that informational eating norms have on quantity of food consumed. Fifteen experimental studies were reviewed. There was evidence that both high intake norms (Z=3.84; P=0.0001; standardized mean difference 0.41, 95% confidence interval 0.20 to 0.63) and low intake norms (Z=2.78; P=0.005; standard mean difference -0.35, 95% confidence interval -0.59 to -0.10) exerted moderate influence on amounts of food eaten. There was consistent evidence that norms influenced food choices; norm information indicating that others make low-energy or high-energy food choices significantly increased the likelihood that participants made similar choices. Information about eating norms influences choice and quantity of food eaten, which could be used to promote healthy changes to dietary behavior.
authors.forename: Eric
authors.initials: E
authors.lastname: Robinson
authors.forename: Jason
authors.initials: J
authors.lastname: Thomas
authors.forename: Paul
authors.initials: P
authors.lastname: Aveyard
authors.forename: Suzanne
authors.initials: S
authors.lastname: Higgs
mesh_terms: D000328:Adult; D004032:Diet / Q000523:psychology*; D002149:Energy Intake; D005247:Feeding Behavior / Q000523:psychology*; D005260:Female; D005518:Food Preferences; D006801:Humans; D016239:MEDLINE; D008297:Male; D008875:Middle Aged; D060756:Social Networking; D012938:Social Perception; D055815:Young Adult
keywords: Eating norms; Food intake; Social networks; Social norms