Portion control tools - do they work in practice?
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This project aimed to investigate the acceptability and usability of a 200-ml portion cup within the family setting on the island of Ireland (IOI). The objectives were:
- To determine patterns of use of a 200-ml portion cup within the family setting
- To determine whether the introduction of the 200-ml portion cup to the household led to behavioural changes regarding portion size
- To gain an in-depth insight into participants’ attitudes towards the usability and acceptability of the portion cup for long-term use within the family setting.
A mixed methods approach was employed to achieve the project objectives. Families from urban and rural settings from across the island of Ireland were recruited via Healthy Living Centres in Northern Ireland and community-based centres in Ireland between June and November 2019. Families participated in a 6-week intervention to test the acceptability and usability of the portion cup. Baseline demographic data was collected following recruitment, and a telephone survey was administered at week 3 and week 6 of the intervention. Four focus group sessions were subsequently conducted (2 in Ireland and 2 in Northern Ireland) between November 2019 and January 2020 to qualitatively explore attitudes towards use of the portion cup within the family setting.
A total of 106 households were recruited from across the IOI and data was collected from 83 households at week 3 (78% retention rate) and 80 households at week 6 (75% retention rate).
Acceptability and usability
- 9 out of 10 households reported using the portion cup for measuring portions at week 3 (90% of households) and week 6 (94% of households).
- Around 9 out of 10 respondents (week 3, 86%; week 6, 91%) reported that the portion cup was ‘very acceptable’.
- The portion cup was acceptable for use in the home setting, but most people stated that it would not be used outside the home.
- Whilst most respondents reported that the portion cup was usable (week 3, 81%; week 6, 73%), some practical issues were raised by a small proportion of respondents including:
- Recommended potion sizes were perceived to be too small
- Markings being erased following repeated washing
- Markings on the portion cup being too small to read
Patterns of use and behaviour change
- Consistent use of the portion cup was observed over the intervention period, and was used:
- by around 8 out of 10 households at breakfast (week 3, 78%; week 6, 78%)
- by around 1 out of 10 households at lunch (week 3, 8%; week 6, 10%)
- by 9 out of 10 households (week 3, 95%; week 6, 94%) for amorphous foods such as cereal, rice or pasta.
- for all members of the household (week 3, 89%; week 6, 86%).
- Feedback from the focus groups, however, suggested that use of the portion cup for all members of the household was transient and that it was only used for measuring children’s portion sizes, initially.
- Engagement by males within the household was limited.
- Daily use of the portion cup diminished by the end of the intervention (week 3, 42%; week 6, 25%) with reported use 4-6 days per week becoming more common by week 6 (week 3, 39%; week 6, 48%).
Capacity building for behaviour change associated with portion sizes
- Most respondents reported that introduction of the portion cup into the household resulted in behavioural changes around portion size including:
- An increased awareness of appropriate portion size
- An improved ability to judge portion size and increased confidence in this regard
- These positive behavioural changes persisted for the duration of the intervention.
- The use of a portion cup within the family setting helped to highlight the importance of portion size, as well as increasing awareness of appropriate portion sizes. Consideration should be given to incorporating the portion cup into public health campaigns along with specific guidance on the recommended number of servings over the course of the day and the size of servings for different food groups.
- The provision of portion cups that are designed for specific stages of the lifecycle i.e. a portion cup for adults or a portion cup for children should be considered to maximise and optimise engagement across the whole family.
- Any portion tools need to be designed so that they are durable and easy to use.
- Consider novel approaches for promoting long-term use and engagement with all members of the household such as integrating the portion cup with existing technologies e.g. by adding a QR (quick response) code to the portion cup, which can sign-post consumers to accessible, detailed, and user-friendly portion size information via an app or website.