Parental beliefs about portion size, not children’s own
beliefs, predict child BMI
, D. Ferriday
, R. L. Griggs
, J. P. Hamilton-Shield
, P. J. Rogers
J. M. Brunstrom
Nutrition and Behaviour Unit, School of
Experimental Psychology, University of Bristol,
NIHR Biomedical Research Unit in
Nutrition, University of Bristol, Bristol, UK
Address for correspondence: C Potter,
Nutrition and Behaviour Unit, School of
Experimental Psychology, University of
Bristol, 12a Priory Road, Clifton, Bristol
BS8 1TU, UK.
Received 26 August 2016; revised 7 February
2017; accepted 10 February 2017
Background: 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.
Methods: 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.
Results: 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 = À.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.
Conclusions: 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.
Keywords: BMI, children, eating behaviour, obesity, parental feeding practices,
Despite being regarded as a serious global health
concern, rates of childhood obesity continue to
increase (1,2). This is a concern because obesity in
childhood greatly increases the risk of being over-
weight in adulthood (2). Recently, food portion sizes
have also increased (3), and several researchers sug-
gest that larger portions have promoted obesity (4,5).
Consistent with this hypothesis, both adults (6) and
children (7) consume signiﬁcantly more food when
presented with larger portions. However, notably,
there is relatively little evidence (8) that overweight
individuals actually select larger portions, and this
relationship remains unclear. Some have found BMI
to be a positive predictor of portion size selection
(9,10), whereas others have found no relationship
(11). To our knowledge, only one study has assessed
the relationship between self-selected portion size
and BMI in young children (aged 3–5 years) (12) –
those children who self-selected larger portions
tended to be overweight.
The selection of larger portions may reﬂect a greater
tolerance for large portions. Obese adults may have a
relatively larger gastric capacity (13). However, the
extent to which this corresponds with the selection
of larger portions remains unclear. To date, the
relationship between children’s tolerance of (and will-
ingness to accept) large portions and child BMI has
not been explored. Parents tend to select their child’s
portions at mealtimes (14) and often encourage their
children to consume all of food that they are served
(15). However, it has been suggested that parents
lack an understanding of age-appropriate portions
for their children (16). Perhaps, for this reason, portion
size plays an important role in determining energy
intake in children (17).
In the present study, as a primary aim, we sought to
determine the relative importance of (i) parental beliefs
about their child’s ideal and maximum tolerated
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium,
provided the original work is properly cited.
Pediatric Obesity 13, 232–238, April 2018 © 2017 The Authors. Pediatric Obesity published by John Wiley & Sons Ltd
on behalf of World Obesity Federation