title: Parental beliefs about portion size, not children's own beliefs, predict child BMI.
abstract: Increases in portion size are thought by many to promote obesity in children. However, this relationship remains unclear. Here, we explore the extent to which a child's BMI is predicted both by parental beliefs about their child's ideal and maximum portion size and/or by the child's own beliefs.
  
  
  
  Parent-child (5-11 years) dyads (N = 217) were recruited from a randomized controlled trial (n = 69) and an interactive science centre (n = 148). For a range of main meals, parents estimated their child's 'ideal' and 'maximum tolerated' portions. Children completed the same tasks.
  
  
  
  An association was found between parents' beliefs about their child's ideal (β = .34, p < .001) and maximum tolerated (β = .30, p < .001) portions, and their child's BMI. By contrast, children's self-reported ideal (β = .02, p = .718) and maximum tolerated (β = -.09, p = .214) portions did not predict their BMI. With increasing child BMI, parents' estimations aligned more closely with their child's own selected portions.
  
  
  
  Our findings suggest that when a parent selects a smaller portion for their child than their child self-selects, then the child is less likely to be obese. Therefore, public health measures to prevent obesity might include instructions to parents on appropriate portions for young children.
authors.affiliation: Nutrition and Behaviour Unit, School of Experimental Psychology, University of Bristol, Bristol, UK.
authors.forename: C
authors.initials: C
authors.lastname: Potter
authors.affiliation: Nutrition and Behaviour Unit, School of Experimental Psychology, University of Bristol, Bristol, UK.
authors.forename: D
authors.initials: D
authors.lastname: Ferriday
authors.affiliation: Nutrition and Behaviour Unit, School of Experimental Psychology, University of Bristol, Bristol, UK.
authors.forename: R L
authors.initials: RL
authors.lastname: Griggs
authors.affiliation: NIHR Biomedical Research Unit in Nutrition, University of Bristol, Bristol, UK.
authors.forename: J P
authors.initials: JP
authors.lastname: Hamilton-Shield
authors.affiliation: Nutrition and Behaviour Unit, School of Experimental Psychology, University of Bristol, Bristol, UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: Rogers
authors.affiliation: Nutrition and Behaviour Unit, School of Experimental Psychology, University of Bristol, Bristol, UK.
authors.forename: J M
authors.initials: JM
authors.lastname: Brunstrom
mesh_terms: D015992:Body Mass Index; D002648:Child; D002652:Child Behavior / Q000523:psychology*; D002675:Child, Preschool; D005247:Feeding Behavior / Q000523:psychology*; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D008297:Male; D062407:Meals; D010287:Parent-Child Relations; D010290:Parents / Q000523:psychology*; D063766:Pediatric Obesity / Q000517:prevention & control; D064787:Portion Size / Q000523:psychology*; D057566:Self Report; D011795:Surveys and Questionnaires
keywords: BMI; children; eating behaviour; obesity; parental feeding practices; portion size