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dc.contributor.advisorHorwath, Caroline
dc.contributor.authorDavidson, Rachel
dc.identifier.citationDavidson, R. (2015). Motivation, Self-determination and Five-year Weight Change (Thesis, Master of Science). University of Otago. Retrieved from
dc.description.abstractBackground: Since traditional weight management approaches have been reported to have poor long terms success, prevention of weight gain has been identified as an important goal. Mid-life, in particular for women, has been recognised as an important life stage for weight gain prevention. Intuitive eating and quality of motivation are two factors that may play a role in the prevention of weight gain. Objectives: To determine, in a population of New Zealand mid-life women: 1. The degree of stability of regulation of eating behaviour scale (REBS) scores over 5 years (ie a measure of quality of motivation derived from Self-Determination Theory). 2. The relationship between REBS and change in Body Mass Index (BMI) over 5 years. 3. Mediators of any relationship between REBS and change in BMI over 5 years, with hypothesized mediators being intuitive eating and other food intake behaviours. Methods: In May 2014, self-administered questionnaires were sent to the cohort of women who had previously participated in the ‘Weight Control Practices and Regulation of Eating Behaviours in New Zealand Women’ longitudinal study. The 5-year followup questionnaire included measures of regulation of eating behaviours, intuitive eating and dietary intake, as well as self-reported weight. These measures and self reported height were also included in most, if not all, of the previous questionnaires (baseline=2009, 2-years=2011, 3-years=2012). Logistic regression was used to determine the odds of having a stable REBS score over 5 years for women in each BMI category. Multiple regression was used to determine if a relationship was present between baseline REBS and change in BMI over 5-years. Once established, mediation analysis was conducted to identify potential mediators of this relationship. Results: At 5-years, questionnaires were returned by 899 women (response rate=73%, mean age=50.6 years). The majority of participants had stable REBS scores at 5-years compared with baseline. Stability was defined as a change of less than 4-points within a subscale, except for autonomous regulation, for which stability was defined as a change of less than 12-points. Compared to women with a healthy BMI, obese women were 38% (P=0.004) more likely to have a decrease of 12-points or more in their autonomous regulation score and 36% (P=0.001) more likely to have an increase of 4-points or more in their amotivation score. When looking at the relationship between specific REBS subscales at baseline and change in BMI over 5-years, a 12-point higher score in autonomous regulation was associated with a 0.20kg/m2 decrease in BMI over 5-years (95% CI: -0.336, -0.057, P=0.006) and a 4-point higher score in amotivation at baseline was associated with a 0.19kg/m2 increase in BMI over 5-years (95% CI: 0.010, 0.361, P=0.039). The relationship between autonomous regulation and change in BMI over 5-years was partially explained by the following mediators: consumption of a greater variety of vegetables, lower consumption of high energy density foods and eating intuitively. For the relationship between amotivation and change in BMI over 5-years, mediators that partially explained the relationship were: consumption of fewer types of vegetables, higher consumption of high energy density foods and less intuitive eating. Conclusion: This study suggests maximising women’s autonomous regulation of eating behaviours and minimising amotivation for eating behaviours may help prevent an increase in BMI over time.
dc.publisherUniversity of Otago
dc.rightsAll items in OUR Archive are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectNew Zealand
dc.subjectEating regulation
dc.subjectWeight change
dc.titleMotivation, Self-determination and Five-year Weight Change
dc.language.rfc3066en Nutrition of Science of Otago
otago.openaccessAbstract Only
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