Volition and Motivation's Influence on Weight Loss Maintenance in the Period Following an Intensive Lifestyle Intervention
Publikation: Bog/antologi/afhandling/rapport › Ph.d.-afhandling › Forskning
The prevalence of overweight and obesity in the world is growing. Because obesity isassociated with a number of serious lifestyle diseases such as hearth disease, a vast amount ofresearch has been devoted to investigate how to assist weight loss, for example through behaviouralweight loss interventions. Regrettably, effects of such interventions are varied and moderate at best.However, Intensive Lifestyle Interventions (ILI) – in which participants live together for 12-14weeks, experience what a healthy lifestyle entails and are taught classes on how to administerphysical activity and diet habits – has been shown to assist a weight loss of 1 % of body weighteach week. Unfortunately, research has also shown that the majority of ILI participants are not ableto maintain the attained weight loss after the ILI. There is growing evidence suggesting thatexercise-specific motivational and self-regulation behaviour strongly moderates the effect ofbehavioural obesity interventions. However, despite this evidence and the promising results of ILIs,a systematic review of the literature in this thesis revealed that neither motivation’s nor volition’simportance to weight loss maintenance in the period that follows an ILI has been investigatedpreviously. The aim of this thesis was to investigate how motivation and volition influence thedifficult task of weight loss maintenance for individuals battling obesity in the period that followsan ILI. To reach this aim, three individual research studies were conducted.Because a validated instrument for measuring the underlying psychological mechanismsbehind self-regulatory behaviour in the exercise context (exercise specific volition) was not readilyavailable, such an instrument had to be developed and validated. In Study 1, the Volition inExercise Questionnaire was validated in a sample of 836 university students. Six volitional factorsbased on 18 items of relevance to exercise participation were identified. The questionnaire showedacceptable model fit, internal consistency, convergent validity, and the ability to explain differencesin exercise participation beyond those explained by the motivational scales of the Sport Motivation Scale.In Study 2, a longitudinal study, a mixed model analysis of 164 ILI participants revealed thatexercise specific volition and motivation influence the task of weight loss maintenance in the periodthat follows an ILI. Based on this study, it was demonstrated that exercise volition and, inparticular, volitional self-confidence and the tendency to postpone training are of importance aboveand beyond autonomous exercise motivation. Results of the study also indicated that extrinsicmotivation can be either facilitating or counterproductive depending on the level of selfdetermination,as identified regulation showed a positive effect 12 months after the intervention,whereas internal regulation showed a negative effect on weight loss.In Study 3 – an interview based qualitative study of 11 successful and 4 unsuccessful ILIweight maintainers – it was shown that important challenges in the period that follows the ILI wereadjusting to life after the intervention, controlling ‘unhealthy’ food intake, and avoiding beingcontrolled by specific situations. Clear differences were seen between successful and unsuccessfulweight maintainers with regards to volition, as described in the Personality Systems InteractionTheory. Other challenges were making weight reduction one’s own project, seeking social support,self-monitoring, choosing exercise activities, as well as eating and exercising for positiveconsequences. In meeting such challenges, motivation is important, and examples were explainedbased on the basic psychological needs and motivation quality described in the Self-determinationTheory. Based on theoretical interpretations of the participants’ experiences, a theoretical modelwas developed. The model illuminates how motivational quality necessitates volitional intensity inorder to maintain goal-oriented behaviour or refrain from goal-opposing behaviour.Overall, this thesis underlined the importance of including all phases of the Rubicon Modelof Action Phases when investigating the motivational aspect of weight loss maintenance following an ILI. The results of the three studies indicated that in order to ensure sustained weight loss, ILIsneed to actively facilitate exercise participation in the period that follows the end of theintervention, and that interventions to sustain participants’ exercise-specific self-determinedmotivation and volitional skills might be the key to ensure this.
|Forlag||Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen|
|Status||Udgivet - 2017|
CURIS 2017 NEXS 242