Encouraging findings for ACT in promoting change in health behaviours has been found. Recently, ACT has been successfully applied to weight
157 management. A brief summary of seven main studies (Lillis et al., 2009; Tapper et al., 2009; Niemeier et al.,, 2012; Weineland, Arvidsson, Kakoulidis & Dahl, 2012; Forman et al., 2012; Katterman et al., 2014; Hill, Masuda, Moore &
Twohig, 2015) in this field are outlined in turn below.
In the United States of America (USA), Lillis et al. (2009) randomly assigned overweight participants (N = 84), who had previously completed six months at weightwatchers, to a waiting list or to a one day ACT-based
workshop targeting obesity-related stigma and psychological distress. Lillis and colleagues proposed that weight loss maintenance was difficult, particularly amongst those with poor coping skills, and therefore, proposed that targeting experiential avoidance may help. At the three month follow-up, ACT participants showed greater improvements in a range of areas including obesity-related stigma, body mass, psychological flexibility and weight-specific acceptance in comparison to the control group. A criticism of this study is that the sample mainly consisted of white, middle-class females and so the generalisability of the findings is questionable. Furthermore, there was no measure of treatment fidelity used in this study which is another limitation.
In the only UK study exploring ACT for weight management, Tapper et al. (2009) randomly assigned females (N = 62) who were motivated to lose weight to attend either four two-hour mindfulness-based workshops or a control condition (instructed to continue with their dieting without further intervention).
Tapper and colleagues highlighted a relationship between emotional eating and obesity, and considered emotional eating as a form of experiential avoidance.
The authors proposed that ACT would help reduce emotional eating and aid weight loss through addressing experiential avoidance. At six months, workshop participants had an increase in physical activity and lost more weight in
comparison to those who did not apply the workshop advice. One drawback of this study was that the intervention had no impact on emotional eating which may have been because of participants’ self-reported difficulty in understanding some of the acceptance-based terminology. This study, like the one by Lillis and colleagues, aimed to complement the weight loss activity the client was already involved in, so did not incorporate specific weight loss techniques.
In the USA, Niemeier et al. (2012) conducted the first study to specifically target emotional overeaters by recruiting those who scored highly on a
158 screening tool for emotional eating. They examined a six-month acceptance-based intervention for weight loss for 21 males and females who had difficulties with internal disinhibition (eating in response to emotions and thoughts). The authors proposed that those who scored highly for emotional eating were more likely to struggle with weight loss. Outcomes from the intervention included weight loss and decreases in internal disinhibition (emotional eating) at follow-up. The authors recommended further investigation of this area with a more heterogeneous sample.
In Sweden, Weineland et al. (2012) conducted a RCT (N = 39) to examine the efficacy of a six week internet-based ACT intervention in preventing weight regain amongst bariatric patients. Participants in the ACT condition showed improvements in eating behaviour (reduction in emotional eating), body dissatisfaction, psychological flexibility and quality of life, in comparison to those in the TAU condition. A methodological limitation of this study was that it did not take objective measures of weight loss. Nevertheless, this study contributes to the field of bariatric research and recommends the need for a detailed evaluation of specific psychological processes of change.
In the USA, Forman et al. (2012) examined the efficacy of an acceptance-based behavioural treatment for weight loss in comparison to a SBT. One hundred and twenty-eight participants were randomly assigned to 40 weeks of either ACT or SBT. Both interventions resulted in weight loss but more weight loss occurred in the acceptance-based treatment group, particularly when administered by experts. The results of the study suggested that acceptance-based approaches are helpful for those who are struggling with weight management and have greater levels of depression and engage in emotional eating. This study and the others reported above may be critiqued on the grounds that the authors measured variables via self-report only, which are vulnerable to demand characteristics. This drawback may be overcome by using an implicit measure such as the IRAP. There are no ACT-based intervention studies which use the IRAP, which is a gap in the literature.
In the USA, Katterman et al. (2014) explored the utility of a brief
acceptance-based behavioural approach (eight group sessions over 16 weeks) in preventing weight gain in 29 female college students, in comparison to a control group (n = 29). The intervention included weight loss strategies and
159 acceptance-based techniques. The results included a decrease in weight and body mass index at 16 weeks which was maintained at a one year follow-up, in comparison to the control group who gained weight. Although the authors highlighted the effectiveness of this intervention, they still questioned how it worked and emphasised the need for further research to determine
mechanisms of change.
Hill and colleagues (2015) conducted the first case-series study
examining the efficacy of an ACT-based intervention in helping two overweight adults with emotional eating. Details of this study provided in the journal paper.
However, briefly, post-intervention, there was a reduction in the number of emotional eating episodes. However, a limitation of this study was that it neglected to measure weight post-intervention. Given that one participant was within the morbidly obese category, this oversight may be perceived as
negligible due to associated health risks. Generally, it is also unlikely that a participant will initiate treatment with the aim of only increasing psychological flexibility or acceptance, as they may be more interested in how such
psychological changes will translate into tangible outcomes.
Regarding the research studies summarised above, ACT appears promising for emotional eating and weight management. Furthermore, the implemented time-frames of interventions varied across studies, ranging from a one day ACT-based workshop (Lillis et al., 2009) to a 40 week acceptance-based behavioural intervention. The majority of studies have been conducted in the USA, with the exception of one conducted in the UK (Tapper et al., 2009).
Therefore, the generalisability of the findings are unknown. This highlights the need for exploration of acceptance-based approaches for weight
loss/management in a UK sample. All studies measured variables via self-report only, which is open to self-report bias. This drawback may be overcome by using an implicit measure71. One other drawback is the lack of a measure of emotional eating with items targeting eating in response to positive emotions.
Another limitation of studies in this area relates to attrition, indicating the need for an effective intervention in this area.
71 See section 1.11 on the IRAP.
160 Furthermore, most studies have utilised RCT methodologies - comparing acceptance based treatment with TAU, as opposed to exploring which parts of the intervention were responsible for change. Therefore, little empirical data is available regarding the mechanisms of change underpinning ACT and further research is advocated in this regard (Gaudiano, 2011; Katterman et al., 2014;
Weineland et al., 2012). SCEDs are a viable option in helping to increase
understanding about the intricacies of psychotherapy and should be considered alongside RCTs (Barlow & Hersen, 1984). The present study aims to address this gap in the evidence-base by exploring the mechanisms of change
underpinning an ACT intervention by adopting a single case methodology.
1.9 A Rationale for Selecting ACT for Emotional Eating and Weight