Plain English Summary
Background and study aims
Being obese (very overweight) can increase significantly the risk of serious diseases such as diabetes, heart disease, cancer and stroke. Studies show that many people gain weight over the Christmas period (average gain 0.5-1.0 kg per holiday) which is then not lost again once the holidays are over. This could mean that a person gains an extra 5-10kg over a ten year period. Whilst there is much publicity about holiday weight gain in the press, few studies address this problem. Many people gain weight over the holiday period because they typically eat a lot of high fat, high calorie food, snack a lot, are less physically active, drink more alcohol, eat more snacks, eat for longer periods and have easy access to food. People often feel holiday periods are a time where they can eat what they choose. There is a need therefore to investigate the effectiveness of simple, low-cost strategies to prevent people from gaining weight. The aims of this study are to assess whether a leaflet can prevent weight gain over the Christmas holiday period; to identify who is most likely to gain weight over Christmas; and to explore what causes people to gain weight.
Who can participate?
Healthy adults aged at least 18 with a BMI of 20.0 kg/m2 or more
What does the study involve?
Participants are randomly allocated to either the intervention (test) group or the usual care group. Those in the usual care group are given a standard information leaflet about healthy lifestyles. Those in the intervention group are given a leaflet that outlines key facts about gaining weight over Christmas and offers top tips to prevent it. This is not a study about dieting over Christmas, as this is unlikely to be acceptable to the public; rather, it is focused on raising awareness about the potential for holiday weight gain and suggests simple ways in which people can ensure a reasonable balance between calories consumed (eaten) and calories burned. The goal is for participants to gain no more than 0.5 kg. Participants are weighed before and after Christmas. Up to 20 participants from the intervention group are also interviewed about their experiences of the study to gain detailed feedback on the strategies used to maintain their weight over Christmas and any barriers they have experienced.
What are the possible benefits and risks of participating?
Potential benefits include prevention of weight gain during Christmas. There are no known risks.
Where is the study run from?
University of Birmingham (UK)
When is the study starting and how long is it expected to run for?
September 2016 to August 2019
Who is funding the study?
University of Birmingham (UK)
Who is the main contact?
Efficacy of a brief public health intervention to prevent weight gain during the Christmas holiday period: randomised controlled trial and nested qualitative study
The research has several aims:
1. To assess whether a brief low cost intervention can prevent weight gain over the Christmas holiday period
2. To identify who is most susceptible to weight gain over Christmas
3. Explore determinants of weight gain through a secondary analysis of the trial data
4. Understand participants’ experiences and thoughts about conscious energy restraint and energy expenditure at Christmas through semi structured interviews
University of Birmingham Science, Technology, Engineering and Mathematics Ethical Review Committee, 28/07/2016, ref: ERN_16_0673
Randomised controlled trial and a qualitative study
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not available in web format, please use the contact details to request a participant information sheet.
Obesity and overweight
Participants will be recruited from community pharmacies, schools (parents) and supermarkets prior to Christmas. They will be randomised to either the intervention or the usual care group.
1. Intervention group: receive a leaflet that outlines key facts about Christmas holiday weight gain and offers top tips (‘Ten Top Tips’ leaflet) to prevent weight gain on holiday. The top ten tips leaflet has already been shown to be effective in community settings and needs minor amendments for use here.
2. Control group: receive an information leaflet about healthy lifestyles.
This is not a study about dieting over Christmas, which would be very unlikely to be acceptable to the public; rather, it is focused on raising awareness about the potential for holiday weight gain and will suggest simple ways in which people can ensure reasonable energy balance, given many never lose the weight gained over Christmas.
The behavioural goal will be for participants to gain no more than 0.5kg of their baseline weight. The primary outcome is change in weight. Participants will be weighed before and after Christmas (follow up). 284 participants will provide 80% power to detect 0.75kg (SD=2.0) difference in weight change between the groups.
Up to 20 participants from the intervention group will be interviewed about their experiences of the study to gain detailed feedback on the behavioural/cognitive strategies used to maintain their weight over Christmas and any barriers they may experienced.
Primary outcome measure
Change in weight from baseline (mid-late November) to follow up (mid-January – early February)
Secondary outcome measures
1. Proportion of participants in both groups who have gained ≤ 0.5 kg at follow up
2. Frequency of self-weighing in the previous two weeks using a single-item measure
3. Change in percentage body fat, measured by bioelectrical impedance at baseline and follow up
4. Difference between groups in cognitive restraint, emotional eating and uncontrolled eating as measured by the three factor eating questionnaire at baseline and follow up
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Aged 18 years or more
2. BMI 20.0 kg/m2 or more
Target number of participants
Participant exclusion criteria
1. Unable to understand English sufficiently to provide written informed consent
2. Women who are known to be pregnant or intending to become pregnant during the study period
3. Women who are breastfeeding
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
University of Birmingham
Department of Primary Care Clinical Sciences College of Medical and Dental Sciences
School of Medicine, PhD Studentship award, University of Birmingham
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
To be confirmed at a later date
Intention to publish date
Participant level data
Available on request
Basic results (scientific)
2018 results in: https://www.ncbi.nlm.nih.gov/pubmed/30530821
- ISRCTN15071781_SAP_15May2018.docx Uploaded 15/05/2018