A pilot study exploring the efficacy of an acceptance and commitment therapy intervention for emotional eating and weight loss maintenance
thesisposted on 01.03.2017, 02:38 by Gallagher, Emma
Weight loss maintenance has emerged as a significant challenge in efforts tackling overweight and obesity, and their associated risks of morbidity and mortality (Colagiuri et al., 2010; NHMRC, 2013; Stubbs & Lavin, 2013). The antidote to the health risks associated with overweight and obesity is weight loss; however, only successful weight loss maintenance results in sustained health benefits (NHMRC, 2013). The statistics show that, while most people can lose weight using traditional behavioural based weight loss strategies, most people regain this lost weight (Wing & Phelan, 2005). Limited, yet cumulative, evidence suggests that the hitherto under explored variable of emotional eating, along with its theoretical underlying mechanism of action, avoidance, may explain significant unaccounted for variance within the weight loss maintenance puzzle (Bryne, 2002; Kayman, Bruvold & Stern, 1990; van Strien, Herman, & Verheijden, 2012). Within the literature addressing overweight and obesity there has been a limited, yet collective, call for researchers to explore novel psychological treatment interventions targeting emotional eating in the context of weight loss maintenance (Koenders & van Strien, 2011; Neve, Morgan & Collins, 2011; Teixeria et al., 2010). An aim of this thesis is to answer this call. In reviewing the problem of emotional eating and weight loss maintenance, as well as the theoretical understanding that avoidance develops and maintains this behaviour, it was reasoned that the psychological treatment intervention Acceptance and Commitment Therapy (ACT) would be best suited to tackling this challenge (Hayes, Strosahl, & Wilson, 2012). This was reasoned because ACT explicitly targets avoidance and related psychological processes within its therapeutic treatment interventions. Consequently, this thesis constitutes the first treatment intervention study to quantitatively bring together ACT and its two core processes of experiential avoidance and cognitive fusion with emotional eating in the context of weight loss maintenance. The global aim of the study was to evaluate the efficacy of a 1-day ACT group workshop treatment intervention for people who had recently lost weight targeting emotional eating to facilitate weight loss maintenance, using a randomised controlled trial design comparing a treatment group to a wait-list control group. Participants (N = 111) volunteered after responding to research advertisements inviting people who struggle with emotional eating and weight loss maintenance to participate. Participants were randomly assigned to the 1-day ACTing on Weight group workshop which was the treatment group, or to the wait-list condition (i.e., the control group). Pre and post-treatment data was collected. The number of people who completed the pre-measures was n = 43 for the treatment group and n = 56 for the control group, and for the post-measures at three months the number of participants was n = 28 and n = 32 respectively. The following variables were psychometrically measured and analysed using multivariate statistics including mediation analyses: emotional eating, weight, weight loss maintenance, body mass index (BMI), waistline, experiential avoidance, weight related experiential avoidance, cognitive fusion, satisfaction with life, positive and negative affect, general health and obesity related well-being. The results show that the participants who attended the 1-day ACTing on Weight group workshop were significantly more likely than the control group to maintain their weight and report decreases in emotional eating, as well as report more weight loss. They were also more likely to report significant improvements in weight related experiential avoidance, cognitive fusion, negative affect, general health and obesity related well-being while satisfaction with life, positive affect, and general experiential avoidance showed non-significant improvements. Further to these main effects, mediational analyses revealed that weight related experiential avoidance was found to serve as a mediator of the effect of the 1-day ACTing on Weight group workshop on 10 of the 13 outcome variables including weight, BMI, five emotional eating scales, satisfaction with life, positive affect and obesity related well-being. In addition, cognitive fusion was found to serve as a mediator of the effect of the 1-day ACTing on Weight group workshop on 9 of the 13 outcome variables including four emotional eating scales, satisfaction with life, general health, positive affect, negative affect and obesity related well-being. The practical implications of the findings are simple. They show that a 1-day ACT group based workshop can decrease emotional eating and improve weight loss maintenance, and related outcomes. The relative brevity of the treatment intervention compared to the previous intervention research also suggests that this approach could be a time and cost effective way to augment weight loss maintenance (Forman, Butryn, Hoffman, & Herbert, 2009; Forman & Butryn et al., 2012; Niemeier, Leahey, Palm Reed, Brown, & Wing, 2012). The theoretical implications are more remarkable for both the relatively distinct domains of the literature of weight loss maintenance and ACT which have been amalgamated through this research. In terms of the weight loss maintenance literature, this study shows that when avoidance, as the theorised common mechanism of action underlying emotional eating is explicitly targeted in a psychological intervention, it can be significantly decreased, which in turn significantly decreases emotional eating. This finding was not surprising given the extent to which all the emotional eating theories purport this to be the case, the finding is however empirically novel (Evers, Stok, & de Ridder, 2010; Kaplan & Kaplan, 1957; Kayman et al., 1990). Also novel is that this study revealed a yet to be published finding showing that cognitive fusion is also a mechanism of action underlying emotional eating. This shows that weight related experiential avoidance and cognitive fusion both increase emotional eating. The practical implication is that future treatment refinement should consider both of these variables in order to optimise successful weight loss maintenance treatment. Through the paradigm of ACT theory and research, these findings support ACT’s therapeutic and unified model of behaviour change. Specifically the findings confirm the theory that experiential avoidance and cognitive fusion serve as mediators of change in ACT treatment interventions. In addition, the results add to the growing list of treatment intervention studies showing that ACT is likely to be helpful for the spectrum of unhelpful eating behaviours as found in recent research (Barnes & Tantleff-Dunn, 2010; Juarascio, Forman, & Herbert, 2010; Lillis & Kendra, in press). Further, this research contributes evidence that supports the proposition that ACT is a transdiagnostic treatment intervention that can be applied to a wide range of health concerns because it targets common underlying mechanisms of action responsible for the development and maintenance of problems as opposed to targeting symptom specific content (Smout, Hayes, Atkins, Klausen, & Duguid, 2012). The primary rationale for this study stems from the continuing rise in the prevalence of overweight and obesity both within Australia and the developed world. As prevalence rises, so to do the adverse health and financial consequences of morbidity and mortality related to overweight and obesity. Finding ways to facilitate improvements in the rates of successful weight loss maintenance to in turn improve morbidity and mortality is presently an unsolved problem. The findings of this research provide some novel answers and direction for future treatment refinement for the problem of emotional eating and unsuccessful weight loss maintenance.