Plain English Summary
Background and study aims
In England, two thirds of the adult population is overweight, with almost 25% of adults being classed as obese and numbers rising. Obesity costs the public £11.4 billion every year and presents a serious danger to individuals, leading to long-term health conditions such as heart disease and diabetes. It is well founded that the best way of losing weight is to combine a reduced-calorie diet with increased exercise but people often struggle to stay motivation for long enough to get lasting results. Self-help treatments and commercial programs tend to be ineffective in the long-term, with many regaining the weight they have lost soon after. Repeated failures to keep weight off can be disheartening and so effective support is needed to help people stay motivated over the longer term, developing lasting habits of healthy eating and regular exercise. A well-established counselling approach called motivational interviewing (MI) has proven to be effective for improving weight loss, but its long-term benefits are quite small. There is an urgent need for better techniques to sustain weight loss over the longer term. A new treatment called Functional Imagery Training (FIT) delivers motivational interviewing in a completely new way, building the client's motivation and confidence by training them to create and rehearse emotionally-charged mental images about their personal goal and how they will achieve it. To make healthy goals more vivid, realistic and concrete, participants are repeatedly encouraged to imagine the benefits of working towards their goals, focusing most on those benefits that will happen right away. The aim of this study is to compare the effectiveness of FIT and MI at helping people to keep off the weight they lose.
Who can participate?
What does the study involve?
Participants are randomly allocated to one of two groups. Those in the first group receive an hour-long face-to-face session of MI, focusing on either diet or physical activity changes (participant’s choice). One week later, participants undertake a 45 minute MI session via telephone with a focus on the same area as chosen in the first session. Two weeks later participants receive 10-20 minute-long booster calls every two weeks for three months and then monthly until the six month follow up to discuss progress, new goals or any issues they are facing. Those in the second group receive an hour-long face-to-face session of FIT, focusing on either diet or physical activity changes (participant’s choice). Participants also receive a 45 minute FTI telephone session two weeks later and booster calls in the same regimen as those in the first group. Participants in this group are also given the opportunity to download an app to help them with imagery training (looking at images to reinforce their mental imagery training). At the start of the study, and then again after six and 12 months, participants in both groups are weighted and measured around the weight to assess their weight loss. Participants also complete a range of questionnaires at the start of the study and after six months to assess their diet and activity levels.
What are the possible benefits and risks of participating?
Participants may benefit from increasing their physical activity levels and losing weight. There are no notable risks involved with participating in this study.
Where is the study run from?
Plymouth University (UK)
When is the study starting and how long is it expected to run for?
September 2014 to December 2016
Who is funding the study?
National Institute for Health Research (UK)
Who is the main contact?
1. Miss Linda Solbrig (public)
2. Professor Jackie Andrade (scientific)
Miss Linda Solbrig
Level 3 Link building
+44 7784 617079
Prof Jackie Andrade
School of Psychology
Portland Square building
+44 1752 584800
Comparison of Functional Imagery Training and Motivational Interviewing for weight loss and increasing physical activity
Functional Imagery Training (FIT) will be more effective than Motivational interviewing for achieving and sustaining weight and increasing physical activity levels.
Faculty Research Ethics Committee, Health and Human Sciences, Plymouth University, 23/03/2015, ref: 14/15-389
Single-centre two-arm partially blinded randomized controlled trial
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not available in web format, please use contact details to request a participant information sheet.
Participants are randomized to one of two groups using web-based randomisation software (https://www.randomizer.org/).
Motivational Interviewing (MI) group:
Participants receive one hour of MI, either focused around diet change or physical activity changes (participant led), in a face to face session. One week later they receive another MI session delivered via phone (around 45 minutes) with a focus on diet or physical activity, dependent on what they had chosen to discuss in their first session. They receive fortnightly booster calls starting two weeks after session two (10-20 minutes) giving opportunity to discuss progress, new goals or any issues participants might be facing. The MI group has no app support.
Functional Imagery Training (FIT) group: Participants receive one hour of FIT, either focused around diet change or physical activity changes (participant led), in a face to face session. One week later they receive another FIT session delivered via phone (around 45 minutes) with a focus on diet or physical activity, dependent on what they had chosen to discuss in their first session. They receive fortnightly booster calls starting two weeks after session two (10-20 minutes) giving opportunity to discuss progress, new goals or any issues participants might be facing. Participants in the FIT group are given the option to download an app to help them with imagery training via practice audios, goal setting options and the opportunity to upload motivational photos.
Follow up for all participants involves coming back to the same laboratory, at six months, to be weighed and measured by research assistants or placement students, not by the original experimenter, to achieve partial blinding. They will meet with the experimenter afterwards to receive £15 payment for taking part and to have a debrief. They will also be given the opportunity to find out what the other group were doing and are offered whichever treatment they had not received.
Primary outcome measure
Weight loss is determined by measuring weight (kg) and waist circumference (cm) at baseline, 6 and 12 months.
Secondary outcome measures
1. Physical activity is measured using the International Physical Activity Questionnaire (IPAQ-short) during session one and one week before follow up at six months
2. Diet is measured using the Food Frequency Questionnaire during session one and one week before follow-up at six months
3. Use of goal imagery is measured using the Thought Frequency Scale at home baseline, one week before session one and the first booster call at the end of trial week four
4. Quality of Life is measured using the QoLIAD (Global Quality of Life Assessment) during session one and one week before follow-up at six months
5. Treatment expectancy/credibility is measured using Credibility/Expectancy Questionnaire after the second session at the end of week two
6. Self-efficacy for exercise is measured using Exercice Self-Efficacy Scale (SCI) one week before session one (lab baseline) at home baseline and at the end of week four after the first booster call
7. Participant experience is measured using the participant experience questionnaire at follow-up
8. Self-efficacy for diet is measured using WELQ (Weight Efficacy Lifestyle Questionnaire)
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. BMI of or above 25
2. Females and males
3. Must be age 18 or above
Target number of participants
Participant exclusion criteria
2. History of eating-disorders
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Link Building Drake Circus
NIHR CLAHRC Southwest Peninsula (PenCLAHRC)
NIHR CLAHRC South West Peninsula
Plymouth Science Park
+44 1392 726055
NIHR CLAHRC Southwest Peninsula (PenCLAHRC)
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Planned publication in a peer reviewed journal.
IPD sharing statement:
The raw data are available at https://zenodo.org/record/1120364.
Intention to publish date
Participant level data
Stored in repository
Basic results (scientific)
2018 results in https://www.ncbi.nlm.nih.gov/pubmed/30185920