Using Implementation Intentions to Self-incentivise Weight-loss

Study Overview
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Brief Summary
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The aim of the present research is to test the effect of helping people to reward themselves when they have successfully lost weight and the impact this will have on subsequent weight. Each participant will be randomly allocated to one of four conditions. The trial requires 200 participants to perform a fully powered statistical analysis. The four conditions are: (1) a control condition, (2) intervention 1 (form a single self-incentivising implementation intention from a drop-down menu), (3) intervention 2 (form multiple self-incentivising implementation intentions from a drop-down menu), or (4) intervention 3 (asked to form a single self-incentivising implementation intention of their own devising). The main outcome measure will be BMI, which will be self-reported.

Official Title
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Using Implementation Intentions to Self-incentivise Weight-loss

Conditions
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Overweight

Intervention / Treatment
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* Behavioral: Single self-incentivising implementation intention
* Behavioral: Multiple self-incentivising implementation intentions
* Behavioral: Self-generated self-incentivising implementation intentions


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged 18+ Exclusion Criteria: Unable or unwilling to complete questionnaire

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 100 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Control<br>Participants will be asked to complete a questionnaire. | |
| Experimental: Intervention 1<br>Single self-incentivising implementation intention After completing a questionnaire, participants will be asked to form a self-incentivising implementation intention: Research shows that rewarding yourself for success can help you to lose weight, but that people often forget to reward themselves. We want you to plan to reward yourself if you achieve your personal weight-loss goal, at the end of 4 weeks. To help you do this, we would like you to complete the following sentence by telling us how you will reward yourself. Please complete the following sentence with a reward of your own choosing. If I lose at least ___lbs/kg by the end of 4 weeks, then I will reward myself by… **Drop down menu** Learning a new skill... | Behavioral: Single self-incentivising implementation intention<br>* Participants are asked to form a single self-incentivising implementation intention (if-then plans)<br>|
| Experimental: Intervention 2<br>Multiple self-incentivising implementation intentions After completing a questionnaire, participants will be asked to form self-incentivising implementation intentions: Research shows that rewarding yourself for success can help you to lose weight, but that people often forget to reward themselves. We want you to plan to reward yourself if you achieve your personal weight-loss goal, at the end of 4 weeks. To help you do this, we would like you to complete the following sentence by telling us how you will reward yourself. You can choose as many rewards as you like! Please complete the following sentence with a reward of your own choosing. If I lose at least ___lbs/kg by the end of 4 weeks, then I will reward myself by… and/or… **Drop down menu** Learning a new skill... | Behavioral: Multiple self-incentivising implementation intentions<br>* Participants are asked to form multiple self-incentivising implementation intentions (if-then plans)<br>|
| Experimental: Intervention 3<br>Self-generated self-incentivising implementation intentions After completing a questionnaire, participants will be asked to form a self-incentivising implementation intention: Research shows that rewarding yourself for success can help you to lose weight, but that people often forget to reward themselves. We want you to plan to reward yourself if you achieve your personal weight-loss goal, at the end of 4 weeks. To help you do this, we would like you to complete the following sentence by telling us how you will reward yourself. Please complete the following sentence with a reward of your own choosing. If I lose at least ___lbs/kg by the end of 4 weeks, then I will reward myself by… | Behavioral: Self-generated self-incentivising implementation intentions<br>* Participants are asked to form a self-incentivising implementation intention (if-then plans) without a drop-down menu<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Body Mass Index | Self-reported | 4 weeks | 
| Actual Use of Self-Rewards | Self-reported | 4 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Capabilities, opportunities and motivations | Self-reported | 4 weeks |