Investigating the key drivers of food portion size among children
: challenges and opportunities in an obesogenic environment

  • Lena Acolatse

Student thesis: Doctoral Thesis


The continued prevalence of overweight and obesity in childhood is of serious public health concern, requiring urgent actions to improve children’s diet. Though an exact causal relationship has yet to be established between the consumption of larger food portion sizes (PS) and obesity, an association can be inferred, as the consumption of larger food PS have been implicated in the global overweight and obesity crises. Additionally, there is evidence of the portion size effect in children – a phenomenon where more food is consumed because more has been presented. The aim of this thesis, therefore was to explore the key drivers of food PS and consumption among children.

A narrative review (Chapter 2) demonstrated the influence of a wide range of interlinked factors on parental decisions regarding child PS, and highlighted the gap in knowledge/awareness of PS guidance. A cross-sectional study (Chapter 3) within representative samples of UK children (4-10 years) demonstrated that daily food intake (g) has decreased over the last decade by approx. 5%, with a parallel increase (+9%) in the frequency of consumption, suggesting that UK children may currently be consuming less food more frequently compared to 10 years ago.

In children aged 7-10 years (n25), a within-subject, repeated measures, randomised cross-over study (Chapter 4) observed that when children self-served a breakfast meal, the PS of ready-to-eat cereal, served and consumed, was significantly higher compared to when they were served ±25% of their self-serve PS. This result suggests that allowing children autonomy over PS might lead to larger PS of food being served and consumed, however, results should be confirmed with other meals. Survey results (Chapter 5) from adults residing in Northern Ireland (n575) indicated that awareness of PS guidance influenced subsequent use of portion control tools (PCTs), however, PCT use was discontinued once PS estimated was similar to that measured.

In conclusion, this thesis demonstrates that PS should be included in larger nutrition interventions and highlights the complexity of PS in general, which should be taken into account in the development of future PS guidance for children 4-10 years. Parents are key stakeholders to improving child nutrition and should be encouraged to practice autonomy provision and the use of PCTs as possible strategies to improve PS.
Date of AwardOct 2023
Original languageEnglish
SupervisorCaomhan Logue (Supervisor), Maeve Kerr (Supervisor), Mary Mc Cann (Supervisor) & Kirsty Pourshahidi (Supervisor)


  • Portion size
  • Children
  • Obesity
  • Dietary patterns
  • Portion control tools
  • Portion size effect
  • Autonomy
  • Downsizing

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