by Michael D. Anestis, M.S.
We have spent a fairly substantial amount of time discussing mindfulness on Psychotherapy Brown Bag. Not only do we find the concept compelling on a personal level, but the data for its utility in various treatment approaches for mental illness and simple day-to-day living is impressive. That being said, today I would like to discuss a recently published study that examined the efficacy of a mindfulness-based treatment approach for weight loss and shed some light on some questions I have regarding their data analysis and conclusions.
The premise for this study, conducted by Katy Tapper and colleagues (2009) and published in the journal Appetite, was that the public would benefit from the development of alternative weight loss treatment approaches. Given the worldwide problem of obesity and data demonstrating that, of individuals who lose weight, less than 5% will maintain their new weight after 4-5 years (Kramer, Jeffery, Forster, & Snell, 1989), this seems more than reasonable. To address this, the authors designed a randomized controlled trial of a new weight loss approach in order to see if it demonstrated potential as a resource for individuals in need of such services.
The new treatment approach, based on Acceptance and Commitment Therapy (ACT) and heavily emphasizing the principles of mindfulness, was chosen because the authors believed that it would help participants reduce their tendency to avoid uncomfortable emotional experiences and help them to view their thoughts as simply thoughts rather than facts upon which they must act. 31 participants were randomly assigned to the treatment condition and 31 were randomly assigned to a control condition. 26 individuals in the treatment group and 25 individuals in the control group took part in all assessments. The intervention itself was designed to be a brief version of ACT, involving attendance at four 2-hour workshops, and was intended to serve as an adjunct to participants' already ongoing efforts to lose weight. In other words, the treatment itself did not provide dietary advice, but rather worked to facilitate success in diets already ongoing for participants. Individuals in the control condition simply continued with their regular weight loss efforts through dieting.
The average Body Mass Index (BMI) for the entire sample was 31.57, which qualifies as obese, and the average age was 41. Individuals in the treatment group did not differ at baseline from individuals in the control group on any important demographic and weight relevant variables, including BMI, age, level of education, number of previous diet attempts, or length of time spent on the current diet attempt. Importantly, however, individuals in the treatment group did report a higher level of binge eating and a lower level of physical activity at baseline than did individuals in the control group. As such, improvements on either variables could, in theory, be accounted for by regression to the mean - the tendency for extreme scores to migrate towards the middle over time.
Before describing the results of this study, I want to briefly cover the basic principles of the treatment itself, as this is our first discussion of ACT on Psychotherapy Brown Bag. Additionally, although I have numerous concerns about this particular study, this should not be interpreted as a critique of ACT in general, but rather simply part of the process of scientific progress, in which results are held up to criticism by peers in order to ensure that interpretations are in line with the evidence.
The treatment itself involved attendance at four 2-hour workshops and involved education on themes central to the principles of ACT. In the first workshop, values and cognitive defusion were emphasized. Values training, in this context, involves helping participants to identify their personal values and determine if weight loss is consistent with those values. The purpose of this is to enhance motivation for treatment adherence. Cognitive defusion involves teaching participants to view their thoughts as simply thoughts rather than seeing them as factual mandates upon which they must act. This is similar to the concept of cognitive restructuring in cognitive behavioral therapy (CBT) and its purpose in the context of treatment is to teach participants to recognize when their own thoughts might serve as unnecessary obstacles in their attempts to lose weight.
The second workshop focuses on control, acceptance/willingness, and self-awareness/mindfulness. The control section teaches participants that attempting to control feelings and bodily sensations might not always be productive. The acceptance/willingness section focuses on teaching participants to accept rather than avoid internal discomfort, whether in the form of negative emotions or a physical sensation such as hunger. This concept is highly consistent with the idea of distress tolerance, a primary focus in dialectical behavior therapy (DBT). The self-awareness/mindfulness section aims to teach participants to focus their attention on the present moment and to allow their thoughts to come and go without judgment. The aim in this section is thus, in large part, to slow down individuals' responses to negative sensations and to break behavioral patterns in which negative feelings prompt unhealthy behaviors aimed at relief.
The third workshop focuses on committed action. In other words, a heavy emphasis is placed on the importance of committing to a lifestyle consistent with one's values. This section essentially serves a motivational role. These first three workshops occur in consecutive weeks with a fourth workshop reviewing prior material taking place three months later. Importantly, participants were asked to complete a series of homework assignments between workshops and were provided with a manual to aid them in proper implementation of ACT skills. As is the case with any effective therapy, only a portion of the work in this brief ACT approach took place in the confines of a session. The client herself was instead required to implement these skills into her own life between sessions.
The treatment outlined above certainly sounds like it has a lot of potential. In fact, ACT has a strong and growing research foundation demonstrating that it is efficacious in the treatment of several mental illnesses. The question for us today, however, is how successful this brief version of ACT was in actually helping participants reduce their weight.
Results for this study, quite frankly, were underwhelming. The authors wanted to see if the treatment was better than the control approach at decreasing BMI, increasing mental health, and increasing physical activity. Data indicated that the treatment condition did not reduce BMI or improve mental health significantly more so than the control condition. The treatment did, however, increase physical activity. At this point, the authors explored several follow-up analyses. Tapper and colleagues (2009) were careful to portray these findings as exploratory, which is important. Nonetheless, their small sample size makes their decision to run a large number of analyses and report on any significant findings highly questionable, as the chances of finding a false positive go up in such scenarios. In their attempts to look for moderators of treatment outcome - that is, variables that help predict why some individuals might benefit more than others from treatment - they only found one significant relationship: the degree to which participants reported still using the skills learned in therapy after six months. The authors decided to eliminate all participants in the treatment group who reported never utilizing these skills (n = 7). This means that, of the 23 treatment participants originally included in the analyses (others were removed due to other reasons such as drop out), nearly one-third reported that they did not use the treatment at all six months later. Given that the treatment itself involved a substantial motivational component, this is highly unimpressive and simply ignoring the results of such a large percentage of their sample seems improper. Nonetheless, the authors ran such analyses and found that the reduced sample in the treatment group now exhibited a significantly greater reduction in BMI scores and increase in physical activity relative to the control group, but still demonstrated no improvement in mental health relative to controls.
So what does this study tell us? Not much, unfortunately. Given the success of DBT in treating binge eating disorder (BED), there is reason to believe that mindfulness could be a useful tool in treating obesity. At the same time, this study simply did not offer much, if any, supportive evidence for this particular ACT-based brief intervention. In order for a treatment to be considered effective, there is a significantly stronger empirical standard that a study must meet. That being said, the authors should be applauded for attempting a study format that is extremely difficult to implement. They were careful to measure relevant variables and report findings that were not necessarily supportive of their hypotheses. Future studies that look at longer or modified version of ACT as a treatment for obesity would be highly useful. In the meantime, however, this approach should not be marketed as an effective way to reduce weight.
If you would like to learn more about Acceptance and Commitment Therapy, we recommend the following resources, all of which are available through our online store:
Mike Anestis is a doctoral candidate in the clinical psychology department at Florida State University.