Eating Behaviors 15 (2014) 694–699
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Eating Behaviors
Development of a novel mindfulness and cognitive behavioral intervention for stress-eating: A comparative pilot study Joyce Corsica ⁎, Megan M. Hood, Shawn Katterman, Brighid Kleinman, Iulia Ivan Rush University Medical Center, United States
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Article history: Received 6 September 2013 Received in revised form 16 June 2014 Accepted 13 August 2014 Available online 21 August 2014 Keywords: Stress-eating Emotional eating Disordered eating Self-medication MBSR CBT
a b s t r a c t Stress-related eating is increasingly cited as a difficulty in managing healthy eating behaviors and weight. However few interventions have been designed to specifically target stress-related eating. In addition, the optimal target of such an intervention is unclear, as the target might be conceptualized as overall stress reduction or changing emotional eating-related thoughts and behaviors. This pilot study compared the effects of three interventions targeting those components individually and in combination on stress-related eating, perceived stress, and weight loss to determine whether the two intervention components are effective alone or are more effective when combined. Fifty-three overweight participants (98% female) who reported elevated levels of stress and stress-eating and were at risk for obesity were randomly assigned to one of three six-week interventions: a modified mindfulness-based stress reduction (MBSR) intervention, a cognitive behavioral stress-eating intervention (SEI), and a combined intervention that included all MBSR and SEI components. All three interventions significantly reduced perceived stress and stress-eating, but the combination intervention resulted in greater reductions and also produced a moderate effect on short term weight loss. Benefits persisted at six week follow-up. The pattern of results preliminarily suggests that the combination intervention (MBSR + SEI) may yield promise in the treatment of stress-related eating. © 2014 Elsevier Ltd. All rights reserved.
1. Introduction Nearly half of all individuals report that they tend to overeat and/or eat hedonically pleasing but calorie-dense/nutrient-poor foods in response to stress (e.g., APA, 2011; Epel, Lapidus, McEwen, & Brownell, 2001; O'Connor, Jones, Conner, McMillan, & Ferguson, 2008). Perceived stress can elicit increased eating through several physiological and behavioral mechanisms, including greater cortisol reactivity and susceptibility to negative mood and/or self-medication (Epel et al., 2001), increased disinhibition (Eysench, Derakshan, Santos, & Calvo, 2007), and increased craving for highly palatable foods (Dallman, Pecoraro, & la Fleur, 2005). Moreover, increased consumption of highly palatable and energy dense foods may be secondary to the combination of life stress and insufficient time, energy, or planning to purchase and prepare healthier food options. Taken together, these factors make those with higher levels of perceived stress more susceptible to choosing the palatable, energy dense, obesogenic foods that are now so readily available in our environment (Horgen & Brownell, 2004). Stress-induced eating is uniquely positioned to increase weight as well as health-detrimental fat depots. Stress is associated with increased ⁎ Corresponding author at: Rush University Medical Center, 1645 W. Jackson, Suite 400, Chicago, IL 60622, United States. Tel.: +1 312 942 2002; fax: +1 312 942 4990. E-mail address: [email protected] (J. Corsica).
http://dx.doi.org/10.1016/j.eatbeh.2014.08.002 1471-0153/© 2014 Elsevier Ltd. All rights reserved.
abdominal fat through repeated activation of the hypothalamicpituitary-adrenal (HPA) axis, which results in the hypersecretion of cortisol and the mobilization of fatty acids to intra-abdominal regions (Dallman et al., 2005). Accumulation of abdominal fat is clearly associated with increased risk of diabetes and cardiovascular disease (Despres, 2006). Stress levels have increased substantially over the past three decades, with women reporting the highest levels of perceived stress (Cohen & Janicki-Deverts, 2012). Given that high levels of perceived stress puts susceptible individuals at higher risk for maladaptive eating, poor food choices, and weight gain/abdominal fat accumulation through a variety of mechanisms, reducing levels of perceived stress and stresseating behaviors in individuals prone to stress-eating could have significant effects on eating behavior. This may subsequently reduce or even prevent stress-induced weight gain and disease development. There are many types of empirically-supported interventions for stress management. One such intervention is Mindfulness-Based Stress Reduction (MBSR, Kabat-Zinn, 1990), an empirically-supported program of stress management that has consistently been shown to reduce perceived stress (Bishop, 2002; Chiesa & Serretti, 2009). The practice of mindfulness and nonjudgmental acceptance of the present experience is thought to decrease emotional reactivity and allow one to respond more calmly and wisely to stressful experiences (Baer, Fischer, & Huss, 2005; Kabat-Zinn, 1990). Mindfulness-based interventions have been adapted to address eating behaviors and have been shown in some
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studies to reduce emotional eating and food cravings, (Alberts, Thewissen, & Raes, 2012) binge eating, (Baer et al., 2005; Courbasson, Nishikawa, & Shapira, 2010; Kristeller & Hallett, 1999) and abdominal fat (Daubenmier et al., 2011). However, many of the studies examining mindfulness-based interventions for eating and/or weight-related behaviors have altered the standard MBSR protocol to include eatingspecific mindfulness exercises, nutritional education, or behavioral techniques (e.g., MB-EAT, Kristeller & Hallett, 1999; MABCT for BED, Courbasson et al., 2010). Due to this variability in the intervention components and lack of (or limited use of) active comparison groups, it is difficult to determine which component(s) of the interventions are responsible for any impact on eating or weight. Thus, it is unclear whether the mindfulness component alone (e.g. standard MBSR) may decrease maladaptive eating behaviors simply by decreasing the overall perception of stress, thereby decreasing the need to eat for the purpose of alleviating stress. Interventions for the treatment of stress eating are rare and most research is extrapolated from the treatment of binge eating. However, stress eating may differ as it does not necessarily involve loss of control over eating or eating excessive quantities. As such, it often goes unrecognized or unaddressed. Cognitive behavioral therapy (CBT) is regarded as one of the most effective psychotherapeutic treatments for binge eating (Sysko & Wilson, 2011; Treasure, Claudino, & Zucker, 2010). Components of CBT programs include psychoeducation about emotions and eating, meal planning and structuring, understanding physical versus emotional hunger, identifying triggers for emotional eating, cognitive restructuring, activity substitution, and relapse prevention (Mitchell, Devlin, de Zwaan, Peterson, & Crow, 2007). Treatment effect sizes in binge eating intervention studies are generally moderate to large (Hilbert et al., 2012). However, it is important to note that stress eating differs from binge eating in significant ways, therefore, the intervention targets may differ. As mentioned, stress-eating is rarely targeted for intervention, despite the fact that it is problematic for a large number of people and can lead to significant weight gain. And while some previous studies have examined the effects of interventions that include mindfulness and eating-related behavioral/educational components on binge eating and weight, none have directly addressed stress eating. Moreover, previous studies have not compared the intervention components (individually and combined) in a randomized study in order to begin to identify the mechanisms of effective treatment for stress eating. This three arm study was designed to compare the effects of mindfulness-based treatment (MBSR), a tailored cognitive-behavioral intervention (stress eating intervention, SEI), and the combination intervention (MBSR + SEI) on perceived stress, stress and emotional eating, and weight. A second goal was to evaluate the feasibility of the interventions. 2. Methods 2.1. Participants Participants were recruited via advertisements soliciting people who “eat poorly when stressed and worry about weight gain,” which were distributed throughout an urban academic medical center and the surrounding community. Eligible participants were those who reported a high level of stress and were at high risk for weight gain and/or obesity, defined as having at least one first degree relative who was overweight or obese, as well as having self-reported (via verbal screening questions) difficulty with one of the following problem eating behaviors: binge eating, frequent emotional or stress eating, intense and irresistible food cravings, or food addiction. Participants were also required to have a BMI over 23 kg/m2 (to allow for the possibility of weight reduction). Individuals were not eligible if they had a current eating disorder or psychotic disorder, were taking medications affecting weight or appetite
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in the past month, had participated in a mindfulness training program, or were currently enrolled in a formal treatment program for weight loss or an eating disorder. 2.2. Procedure Interested individuals completed a brief study eligibility screening over the phone prior to being scheduled for an in-person visit, at which time informed consent was obtained and physiological and self-report assessments were conducted. Participants were then randomized to one of three groups: (1) Mindfulness-based stress reduction (MBSR) training, (2) Stress-eating intervention (SEI), or (3) MBSR + SEI. All groups met once per week for 50 (MBSR and SEI groups) or 80 (MBSR + SEI group) minutes for six consecutive weeks. Six groups were held in total (two per condition) and the study therapists, clinical psychologists with postdoctoral training in both MBSR and the treatment of disordered eating behaviors (JC and MH), led one group in each of the three conditions. Post-treatment and follow up assessment data were gathered at the end of the sixth session (post-treatment) and at six weeks following the conclusion of treatment (follow-up), respectively. 2.3. Measures The Perceived Stress Scale (PSS-10; Cohen, Karmarck, & Mermelstein, 1983) is a well-validated 10-item, one-factor inventory that is frequently used to measure perceived stress in MBSR and other clinical intervention studies (e.g., Carmody, Crawford, & Churchill, 2006; Chang et al., 2004). The scale measures the extent to which participants perceive their life circumstances over the past month as stressful (i.e., unpredictable, uncontrollable, and overloading). Items are rated on a 4-point scale ranging from 0 (never) to 4 (very often), with higher scores reflecting greater perceived stress. The PSS-10 has demonstrated adequate internal consistency (alpha = .75), test–retest reliability, and construct validity (Cohen et al., 1983). The alpha of the PSS-10 in this study was .87. The Eating and Appraisal Due to Emotions and Stress Questionnaire (EADES; Ozier et al., 2007), Emotion- and Stress-Related Eating subscale (EADES-ESE, one of three subscales on the EADES) is comprised of 24 questions that evaluate the extent to which individuals use food to cope with emotions and stress, and includes questions related to both eating behaviors and eating-related self-efficacy. Scores range from 24 to 120, with lower scores represent poorer functioning. The EADES exhibited good reliability in the standardization sample (alpha = .95, Ozier et al., 2007) and the alpha for the EADES-ESE in this sample was .92. Weight was measured with shoes off in light street clothing on a medical grade scale during each visit. Height was self-reported. 2.3.1. End of program assessment form Participants in the mindfulness groups responded to four questions inquiring how often they read the materials and completed formal (body scan, sitting meditation, mindful self-inquiry, mindful yoga, loving kindness meditation) and informal practice (everyday mindfulness, weaving mindfulness throughout the day, mindful eating, mindful listening, etc). Possible responses were once/week, 2–3 x/week, 4–5x/week, 6–7x/week, and multiple times a day. 2.4. Interventions 2.4.1. Mindfulness based stress reduction training This empirically supported intervention was based on Jon KabatZinn’s Mindfulness Based Stress Reduction (Kabat-Zinn, 1990) program, adapted to a 6-session format. A workbook (A Mindfulness-Based Stress Reduction Workbook by Stahl & Goldstein, 2010) was provided to each group member to read and reference for homework assignments. The content of each MBSR session is detailed in Table 1. Each session began with a review of the previous session material as well as between
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Table 1 MBSR and SEI intervention components. Session MBSR 1 2 3 4 5 6
SEI
Introduction to mindfulness
Introduction to stress & stress-eating; Meal planning and nutrition Mindfulness and stress Identifying and reducing stress-eating reduction foods and triggers Deepening practice; yoga Cognitive behavioral strategies for stress eating Loving-kindness meditation Introduction to exposure and response prevention for stress eating Interpersonal mindfulness Exposure and response prevention for stress eating Mindful health and maintenance Problem solving training and prevention
session practice, and instruction in the topic scheduled for that day. Each new technique was practiced during the group. Homework assignments included readings in the workbook and daily formal (time set aside for meditation) and informal (mindfulness of daily activities) mindfulness and meditation practice, totaling 30–45 minutes per day.
2.4.2. Stress eating intervention This novel intervention was developed based on the interrelationship between stress, eating and well-being, combined with components of empirically supported interventions for binge/emotional eating. The intervention was cognitive behavioral and exposure-based, and included stress education, identifying and monitoring common stress-eating situations, nutrition education, cognitive restructuring, exposure and response prevention, alternate activities identification & rehearsal, and relapse prevention. Similar to the MBSR condition, each session began with a review of the previous session’s material, followed by instruction and discussion of the day’s scheduled topic (see Table 1). As with the MBSR condition, handouts and homework (identifying stressful situations, creating a healthy eating plan, replacing stress-eating foods, creating pleasurable activity and stress reduction lists, imaginal and in vivo exposures) were given at each session. 2.4.3. Combination intervention The MBSR + SEI group included full content from each MBSR and SEI session. The MBSR content was covered first in each session, followed by the SEI content.
ITT = Intention-to-treat analysis Fig. 1. Participant flow diagram. ITT = Intention-to-treat analysis.
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2.4.3.1. Statistics. Data analyses were conducted using SPSS version 17.0 with a significance level of p b .05. For scales missing data on one item, the mean subscale value was imputed for these items. Participants (labeled “completers”) were included in final analyses if they attended at least 50% of sessions and completed each assessment. Baseline data comparisons between completers and non-completers were made using independent-sample t tests for continuous variables and χ2 tests for independence for categorical variables. A repeated-measures, mixed-design ANOVA with group (MBSR, SEI, and MBSR + SEI) as the between-subjects factor and time (baseline, post-treatment, follow up) as the within-subjects factor compared perceived stress, stress and emotional eating, and weight between the three study groups. A secondary intention-to-treat analysis was also performed for all participants, with the last observation carried forward method used for management of missing data.
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Fig. 3. EADES scores by treatment condition.
3. Results
3.3. Group comparisons of completers
3.1. Recruitment and retention
3.3.1. Perceived stress Repeated measures ANOVA indicated a main effect of time (F(2,22) = 8.86, p = .002). The main effect of group and the time by group interaction were non-significant. As displayed in Fig. 2, PSS scores decreased from pre- to post-treatment in all three groups with a large effect, with the greatest improvement in stress in the MBSR + SEI group.
Of 123 individuals who were screened for eligibility, 53 met all eligibility criteria and were randomized to one of the three study conditions: MBSR (N = 19), SEI (N = 20), or MBSR + SEI (N = 14) (Fig. 1). Following randomization, eight participants withdrew or failed to begin their assigned treatments (1 in MBSR + SEI, 4 in SEI, and 3 in MBSR) and eight attended fewer than 3 treatment sessions (1 in MBSR + SEI, 4 in SEI, and 3 in MBSR). Of the participants who received the treatment (“completers” who attended at least 50% of sessions; Santorelli & Kabat-Zinn, 2012), 92% of MBSR + SEI (11 of 12), 100% of MBSR (12 of 12), and 77% of SEI (10 of 13) participants completed the 6-week and 12-week assessments. Completers and non-completers did not differ by treatment group or by gender, age, education, or baseline BMI (all ps N .05).
3.2. Sample characteristics Participants were mostly female (98%), middle aged (M = 45.4 years, SD = 10.4), college educated (M = 16.7 years, SD = 2.4), and overweight/obese (M BMI = 35.0 kg/m2, SD = 9.0, range 23.9 to 60.0). Ethnic background was diverse, with 41% Caucasian, 37% African American, 16% Hispanic, and 6% other.
3.3.2. Stress eating Repeated measures ANOVA indicated a significant main effect of time (F(2,24) = 18.02, p b .001). The main effect of group and the time by group interaction were non-significant. As displayed in Fig. 3, stress eating scores increased (indicating better functioning/improvement) in all groups with a large effect, with the greatest improvement in the MBSR + SEI group. 3.3.3. Weight Repeated measures ANOVA indicated a significant main effect of time (F(2, 29) = 5.04, p = .01), but non-significant main effect of group and time by group interaction. As displayed in Fig. 4, in the MBSR + SEI and SEI groups, weights decreased across the course of the study. For the MBSR group, weight initially increased slightly from pre- to post-treatment, before returning to baseline levels at follow up. 3.3.4. Testing the combination intervention Effects of MBSR + SEI on Stress Eating, Perceived Stress, and Weight Scores for MBSR + SEI participants on each outcome measure are shown in Table 2. Repeated measures ANOVA indicated significantly decreased perceived stress (F(2,6) = 5.71, p = .04) and significantly
Fig. 2. PSS scores by treatment condition.
Fig. 4. Weight loss by treatment condition.
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Table 2 MBSR + SEI scores over time.
EADES-SE⁎ PSS⁎ Weight
Baseline
Post-treatment
Follow-up
Partial eta2
60.10 (18.34) 21.40 (7.97) 211.82 (55.52)
79.18 (10.33) 13.70 (8.11) 212.00 (58.48)
85.00 (8.31) 11.67 (7.09) 210.23 (57.58)
.83 .66 .16
EADES-SE, Eating and Appraisal Due to Emotions and Stress Questionnaire-Emotion and Stress-Related Eating scale, higher scores indicate better functioning. PSS, Perceived Stress Scale, higher scores indicate more stress. ⁎ p b .05 in repeated measures ANOVA.
decreased stress/emotional eating (F(2,7) = 17.39, p = .002), Although a modest weight loss was also achieved, it was not statistically significant (p = .47). There was, however, a moderate effect size for weight loss in this group. 3.4. Intention-to-treat analysis. All group comparison analyses were also completed with an intention-to-treat method using last observation carried forward to account for missing data. The same significance patterns were found in each analysis. 3.5. Feasibility and integrity of the interventions We evaluated the feasibility of the intervention through several means: Evaluating the recruitment rate, evaluating the participant dropout rate, evaluating participant-reported use of learned strategies, and noting informal participant feedback and requests. The recruitment rate for this study was very high. We had a strong response (123 calls) to recruitment efforts. Of those who indicated interest, 40% met the criteria for study entry, indicating that recruiting for this study is highly feasible. Next, the drop-out rate was low (14%), which is superior to or equal to other mindfulness and disordered eating interventions (Katterman, Kleinman, Hood, Nackers, & Corsica, 2014). Although we were unable to test group differences due to small sample sizes, the MBSR + SEI group had fewer drop-outs than the MBSR or SEI groups (1 vs 3 vs 4, respectively), indicating that participants may have found it more acceptable, useful, and/or enjoyable. At the end of the study, participants completed a questionnaire about their use of intervention strategies. The majority of participants (90%) indicated that they continued to use the intervention components at least once a week. Participants were also asked what they would recommend changing in a future intervention. The only substantive suggestion for improvement, recommended by several participants, was for a longer course of treatment and follow-up. Anecdotally, participants reported finding the intervention acceptable and useful. Treatment integrity was evaluated by comparing the outcome of the intervention across both group leaders. There were no significant group differences in any treatment outcomes based on group leader (p N .05), indicating that the manualized intervention was reasonably standardized and delivered and that the effect of the intervention was not dependent on therapist characteristics. 4. Discussion Approximately 50% of people report engaging in stress-related overeating. With perceived stress levels higher than ever before, stresseating constitutes a very real threat to effective weight management. Few studies have developed and tested treatments aimed specifically at reducing stress-related eating, and none have compared the effects of targeting different mechanisms thought to contribute to stress eating (high perceived stress vs the actual behavior of choosing and eating hedonically pleasing foods). This intervention was developed in order to begin to identify the components of stress-eating that are optimal targets for intervention (i.e. stress vs. eating in response to stress), and
thus, begin to identify mechanisms of change in the treatment of stress eating. Our main goal was to compare the effectiveness of intervention components that directly and indirectly targeted stress and stress-related eating. We theorized that targeting overall stress with a mindfulnessbased stress reduction (MBSR) intervention may reduce stress-eating behaviors without specifically targeting those behaviors, but rather, by reducing perceived stress through increased mindfulness. We compared MBSR with a focused stress-eating intervention developed for this study that directly addressed the problem of eating in reaction to stress through cognitive and behavioral strategies. This intervention included education on the psychological and biological impact of stresseating, improving nutrition, reducing intake of sugar and processed foods (that tend to promote continued reliance on eating to cope with stress), developing alternate coping strategies, and repeated and structured in vivo exposure to “problem” foods while under stress. The last component was unique in teaching participants how, under stressful circumstances, to learn to resist eating convenient, tempting, but low quality foods and learn new ways of responding. Lastly, we hypothesized that combining the mindfulness and stresseating intervention would more comprehensively address stress-eating by tackling two different components of the experience, and prove to be of superior effectiveness in addressing stress-eating, perceived stress and possibly even weight (although as a six week study that did not specifically target weight, that expectation was not high). The study had three main findings. First, all three interventions resulted in significant improvement in the target variables of perceived stress and stress eating. In addition, these effects appear to have been maintained and in some cases, even improved over time, as further reductions were apparent at follow-up. Second, while all groups exhibited improvements in symptoms, the combination intervention appeared to result in the best overall outcomes at post treatment, suggesting that combining both a mindfulness-based treatment for general stress reduction and a cognitive behavioral treatment targeting stress-eating behavior directly may be the most effective strategy for reducing stress and stress-eating. Third, we found that the mindfulness and stresseating intervention components as developed and executed were feasible and standardizable. Anecdotally, in verbal discussions following the completion of the groups, most treatment completers indicated that the interventions were highly acceptable and that they continued to use the strategies they had learned. The main strength of this study was in developing and executing an intervention that specifically targets stress eating and in the comparative assessment of the impact of different intervention components on stress-eating that had, in previous studies of emotional and binge eating, been difficult to disentangle. Other interventions (see Katterman et al., 2014 for a recent review) have used mindfulness successfully in the treatment of binge eating and emotional eating, and have occasionally been useful in weight loss. However, because the mindfulness interventions were adapted by adding nutritional and/or eating management components, it is unclear whether mindfulness or eating management contributed to the success. In addition, because of the lack of control or comparison groups, it is unclear whether this is a general therapeutic attention finding. The interventions tested in this study differed in that they focused individually on the two different components of the stress-eating experience (overall stress versus the stresseating thoughts and behaviors) and also combined the components. Thus, we had three comparison groups, each with the same leader, enabling us to rule out attention and general intervention effects. Lastly, to our knowledge, this is the first intervention to use an exposure-based treatment component as part of the cognitive-behavioral treatment of stress-eating, a component that we believe enhances applicability to real-world stress eating. The main limitations of this pilot study were related to small sample size, participant drop out, and the almost entirely female composition of the sample, all of which should be addressed in future studies to improve
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statistical power and generalizability. In addition, closer examination of participants’ daily food choices, caloric and macronutrient intake, waist circumference, and biological indicators of stress (e.g. cortisol levels) would be useful in order to assess the dietary and physiological impact of the different interventions. This would contribute to a further understanding of the mechanisms of change in the treatment of stress-eating. However, our findings suggest that an approach that addresses both perceived stress through mindfulness and maladaptive eating behaviors through exposure based cognitive behavioral treatment has the potential to show the greatest impact on an eating and weight difficulty that is reported by nearly half of the population. Role of funding sources Funding for this study was provided by the Roberts Fund. The Roberts Fund had no role in the study design, collection, analysis or interpretation of the data, writing the manuscript, or the decision to submit the paper for publication. Contributors Authors 1 and 2 designed the study and wrote the protocol. Authors 1, 2, 3, 4, and 5 conducted literature searches and provided summaries of previous research studies. Author 2 conducted the statistical analysis. Author 1 wrote the first draft of the manuscript and all authors contributed to and have approved the final manuscript. Conflict of interest All authors declare that they have no conflicts of interest.
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Contents lists available at ScienceDirect
Eating Behaviors
Development of a novel mindfulness and cognitive behavioral intervention for stress-eating: A comparative pilot study Joyce Corsica ⁎, Megan M. Hood, Shawn Katterman, Brighid Kleinman, Iulia Ivan Rush University Medical Center, United States
a r t i c l e
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Article history: Received 6 September 2013 Received in revised form 16 June 2014 Accepted 13 August 2014 Available online 21 August 2014 Keywords: Stress-eating Emotional eating Disordered eating Self-medication MBSR CBT
a b s t r a c t Stress-related eating is increasingly cited as a difficulty in managing healthy eating behaviors and weight. However few interventions have been designed to specifically target stress-related eating. In addition, the optimal target of such an intervention is unclear, as the target might be conceptualized as overall stress reduction or changing emotional eating-related thoughts and behaviors. This pilot study compared the effects of three interventions targeting those components individually and in combination on stress-related eating, perceived stress, and weight loss to determine whether the two intervention components are effective alone or are more effective when combined. Fifty-three overweight participants (98% female) who reported elevated levels of stress and stress-eating and were at risk for obesity were randomly assigned to one of three six-week interventions: a modified mindfulness-based stress reduction (MBSR) intervention, a cognitive behavioral stress-eating intervention (SEI), and a combined intervention that included all MBSR and SEI components. All three interventions significantly reduced perceived stress and stress-eating, but the combination intervention resulted in greater reductions and also produced a moderate effect on short term weight loss. Benefits persisted at six week follow-up. The pattern of results preliminarily suggests that the combination intervention (MBSR + SEI) may yield promise in the treatment of stress-related eating. © 2014 Elsevier Ltd. All rights reserved.
1. Introduction Nearly half of all individuals report that they tend to overeat and/or eat hedonically pleasing but calorie-dense/nutrient-poor foods in response to stress (e.g., APA, 2011; Epel, Lapidus, McEwen, & Brownell, 2001; O'Connor, Jones, Conner, McMillan, & Ferguson, 2008). Perceived stress can elicit increased eating through several physiological and behavioral mechanisms, including greater cortisol reactivity and susceptibility to negative mood and/or self-medication (Epel et al., 2001), increased disinhibition (Eysench, Derakshan, Santos, & Calvo, 2007), and increased craving for highly palatable foods (Dallman, Pecoraro, & la Fleur, 2005). Moreover, increased consumption of highly palatable and energy dense foods may be secondary to the combination of life stress and insufficient time, energy, or planning to purchase and prepare healthier food options. Taken together, these factors make those with higher levels of perceived stress more susceptible to choosing the palatable, energy dense, obesogenic foods that are now so readily available in our environment (Horgen & Brownell, 2004). Stress-induced eating is uniquely positioned to increase weight as well as health-detrimental fat depots. Stress is associated with increased ⁎ Corresponding author at: Rush University Medical Center, 1645 W. Jackson, Suite 400, Chicago, IL 60622, United States. Tel.: +1 312 942 2002; fax: +1 312 942 4990. E-mail address: [email protected] (J. Corsica).
http://dx.doi.org/10.1016/j.eatbeh.2014.08.002 1471-0153/© 2014 Elsevier Ltd. All rights reserved.
abdominal fat through repeated activation of the hypothalamicpituitary-adrenal (HPA) axis, which results in the hypersecretion of cortisol and the mobilization of fatty acids to intra-abdominal regions (Dallman et al., 2005). Accumulation of abdominal fat is clearly associated with increased risk of diabetes and cardiovascular disease (Despres, 2006). Stress levels have increased substantially over the past three decades, with women reporting the highest levels of perceived stress (Cohen & Janicki-Deverts, 2012). Given that high levels of perceived stress puts susceptible individuals at higher risk for maladaptive eating, poor food choices, and weight gain/abdominal fat accumulation through a variety of mechanisms, reducing levels of perceived stress and stresseating behaviors in individuals prone to stress-eating could have significant effects on eating behavior. This may subsequently reduce or even prevent stress-induced weight gain and disease development. There are many types of empirically-supported interventions for stress management. One such intervention is Mindfulness-Based Stress Reduction (MBSR, Kabat-Zinn, 1990), an empirically-supported program of stress management that has consistently been shown to reduce perceived stress (Bishop, 2002; Chiesa & Serretti, 2009). The practice of mindfulness and nonjudgmental acceptance of the present experience is thought to decrease emotional reactivity and allow one to respond more calmly and wisely to stressful experiences (Baer, Fischer, & Huss, 2005; Kabat-Zinn, 1990). Mindfulness-based interventions have been adapted to address eating behaviors and have been shown in some
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studies to reduce emotional eating and food cravings, (Alberts, Thewissen, & Raes, 2012) binge eating, (Baer et al., 2005; Courbasson, Nishikawa, & Shapira, 2010; Kristeller & Hallett, 1999) and abdominal fat (Daubenmier et al., 2011). However, many of the studies examining mindfulness-based interventions for eating and/or weight-related behaviors have altered the standard MBSR protocol to include eatingspecific mindfulness exercises, nutritional education, or behavioral techniques (e.g., MB-EAT, Kristeller & Hallett, 1999; MABCT for BED, Courbasson et al., 2010). Due to this variability in the intervention components and lack of (or limited use of) active comparison groups, it is difficult to determine which component(s) of the interventions are responsible for any impact on eating or weight. Thus, it is unclear whether the mindfulness component alone (e.g. standard MBSR) may decrease maladaptive eating behaviors simply by decreasing the overall perception of stress, thereby decreasing the need to eat for the purpose of alleviating stress. Interventions for the treatment of stress eating are rare and most research is extrapolated from the treatment of binge eating. However, stress eating may differ as it does not necessarily involve loss of control over eating or eating excessive quantities. As such, it often goes unrecognized or unaddressed. Cognitive behavioral therapy (CBT) is regarded as one of the most effective psychotherapeutic treatments for binge eating (Sysko & Wilson, 2011; Treasure, Claudino, & Zucker, 2010). Components of CBT programs include psychoeducation about emotions and eating, meal planning and structuring, understanding physical versus emotional hunger, identifying triggers for emotional eating, cognitive restructuring, activity substitution, and relapse prevention (Mitchell, Devlin, de Zwaan, Peterson, & Crow, 2007). Treatment effect sizes in binge eating intervention studies are generally moderate to large (Hilbert et al., 2012). However, it is important to note that stress eating differs from binge eating in significant ways, therefore, the intervention targets may differ. As mentioned, stress-eating is rarely targeted for intervention, despite the fact that it is problematic for a large number of people and can lead to significant weight gain. And while some previous studies have examined the effects of interventions that include mindfulness and eating-related behavioral/educational components on binge eating and weight, none have directly addressed stress eating. Moreover, previous studies have not compared the intervention components (individually and combined) in a randomized study in order to begin to identify the mechanisms of effective treatment for stress eating. This three arm study was designed to compare the effects of mindfulness-based treatment (MBSR), a tailored cognitive-behavioral intervention (stress eating intervention, SEI), and the combination intervention (MBSR + SEI) on perceived stress, stress and emotional eating, and weight. A second goal was to evaluate the feasibility of the interventions. 2. Methods 2.1. Participants Participants were recruited via advertisements soliciting people who “eat poorly when stressed and worry about weight gain,” which were distributed throughout an urban academic medical center and the surrounding community. Eligible participants were those who reported a high level of stress and were at high risk for weight gain and/or obesity, defined as having at least one first degree relative who was overweight or obese, as well as having self-reported (via verbal screening questions) difficulty with one of the following problem eating behaviors: binge eating, frequent emotional or stress eating, intense and irresistible food cravings, or food addiction. Participants were also required to have a BMI over 23 kg/m2 (to allow for the possibility of weight reduction). Individuals were not eligible if they had a current eating disorder or psychotic disorder, were taking medications affecting weight or appetite
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in the past month, had participated in a mindfulness training program, or were currently enrolled in a formal treatment program for weight loss or an eating disorder. 2.2. Procedure Interested individuals completed a brief study eligibility screening over the phone prior to being scheduled for an in-person visit, at which time informed consent was obtained and physiological and self-report assessments were conducted. Participants were then randomized to one of three groups: (1) Mindfulness-based stress reduction (MBSR) training, (2) Stress-eating intervention (SEI), or (3) MBSR + SEI. All groups met once per week for 50 (MBSR and SEI groups) or 80 (MBSR + SEI group) minutes for six consecutive weeks. Six groups were held in total (two per condition) and the study therapists, clinical psychologists with postdoctoral training in both MBSR and the treatment of disordered eating behaviors (JC and MH), led one group in each of the three conditions. Post-treatment and follow up assessment data were gathered at the end of the sixth session (post-treatment) and at six weeks following the conclusion of treatment (follow-up), respectively. 2.3. Measures The Perceived Stress Scale (PSS-10; Cohen, Karmarck, & Mermelstein, 1983) is a well-validated 10-item, one-factor inventory that is frequently used to measure perceived stress in MBSR and other clinical intervention studies (e.g., Carmody, Crawford, & Churchill, 2006; Chang et al., 2004). The scale measures the extent to which participants perceive their life circumstances over the past month as stressful (i.e., unpredictable, uncontrollable, and overloading). Items are rated on a 4-point scale ranging from 0 (never) to 4 (very often), with higher scores reflecting greater perceived stress. The PSS-10 has demonstrated adequate internal consistency (alpha = .75), test–retest reliability, and construct validity (Cohen et al., 1983). The alpha of the PSS-10 in this study was .87. The Eating and Appraisal Due to Emotions and Stress Questionnaire (EADES; Ozier et al., 2007), Emotion- and Stress-Related Eating subscale (EADES-ESE, one of three subscales on the EADES) is comprised of 24 questions that evaluate the extent to which individuals use food to cope with emotions and stress, and includes questions related to both eating behaviors and eating-related self-efficacy. Scores range from 24 to 120, with lower scores represent poorer functioning. The EADES exhibited good reliability in the standardization sample (alpha = .95, Ozier et al., 2007) and the alpha for the EADES-ESE in this sample was .92. Weight was measured with shoes off in light street clothing on a medical grade scale during each visit. Height was self-reported. 2.3.1. End of program assessment form Participants in the mindfulness groups responded to four questions inquiring how often they read the materials and completed formal (body scan, sitting meditation, mindful self-inquiry, mindful yoga, loving kindness meditation) and informal practice (everyday mindfulness, weaving mindfulness throughout the day, mindful eating, mindful listening, etc). Possible responses were once/week, 2–3 x/week, 4–5x/week, 6–7x/week, and multiple times a day. 2.4. Interventions 2.4.1. Mindfulness based stress reduction training This empirically supported intervention was based on Jon KabatZinn’s Mindfulness Based Stress Reduction (Kabat-Zinn, 1990) program, adapted to a 6-session format. A workbook (A Mindfulness-Based Stress Reduction Workbook by Stahl & Goldstein, 2010) was provided to each group member to read and reference for homework assignments. The content of each MBSR session is detailed in Table 1. Each session began with a review of the previous session material as well as between
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Table 1 MBSR and SEI intervention components. Session MBSR 1 2 3 4 5 6
SEI
Introduction to mindfulness
Introduction to stress & stress-eating; Meal planning and nutrition Mindfulness and stress Identifying and reducing stress-eating reduction foods and triggers Deepening practice; yoga Cognitive behavioral strategies for stress eating Loving-kindness meditation Introduction to exposure and response prevention for stress eating Interpersonal mindfulness Exposure and response prevention for stress eating Mindful health and maintenance Problem solving training and prevention
session practice, and instruction in the topic scheduled for that day. Each new technique was practiced during the group. Homework assignments included readings in the workbook and daily formal (time set aside for meditation) and informal (mindfulness of daily activities) mindfulness and meditation practice, totaling 30–45 minutes per day.
2.4.2. Stress eating intervention This novel intervention was developed based on the interrelationship between stress, eating and well-being, combined with components of empirically supported interventions for binge/emotional eating. The intervention was cognitive behavioral and exposure-based, and included stress education, identifying and monitoring common stress-eating situations, nutrition education, cognitive restructuring, exposure and response prevention, alternate activities identification & rehearsal, and relapse prevention. Similar to the MBSR condition, each session began with a review of the previous session’s material, followed by instruction and discussion of the day’s scheduled topic (see Table 1). As with the MBSR condition, handouts and homework (identifying stressful situations, creating a healthy eating plan, replacing stress-eating foods, creating pleasurable activity and stress reduction lists, imaginal and in vivo exposures) were given at each session. 2.4.3. Combination intervention The MBSR + SEI group included full content from each MBSR and SEI session. The MBSR content was covered first in each session, followed by the SEI content.
ITT = Intention-to-treat analysis Fig. 1. Participant flow diagram. ITT = Intention-to-treat analysis.
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2.4.3.1. Statistics. Data analyses were conducted using SPSS version 17.0 with a significance level of p b .05. For scales missing data on one item, the mean subscale value was imputed for these items. Participants (labeled “completers”) were included in final analyses if they attended at least 50% of sessions and completed each assessment. Baseline data comparisons between completers and non-completers were made using independent-sample t tests for continuous variables and χ2 tests for independence for categorical variables. A repeated-measures, mixed-design ANOVA with group (MBSR, SEI, and MBSR + SEI) as the between-subjects factor and time (baseline, post-treatment, follow up) as the within-subjects factor compared perceived stress, stress and emotional eating, and weight between the three study groups. A secondary intention-to-treat analysis was also performed for all participants, with the last observation carried forward method used for management of missing data.
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Fig. 3. EADES scores by treatment condition.
3. Results
3.3. Group comparisons of completers
3.1. Recruitment and retention
3.3.1. Perceived stress Repeated measures ANOVA indicated a main effect of time (F(2,22) = 8.86, p = .002). The main effect of group and the time by group interaction were non-significant. As displayed in Fig. 2, PSS scores decreased from pre- to post-treatment in all three groups with a large effect, with the greatest improvement in stress in the MBSR + SEI group.
Of 123 individuals who were screened for eligibility, 53 met all eligibility criteria and were randomized to one of the three study conditions: MBSR (N = 19), SEI (N = 20), or MBSR + SEI (N = 14) (Fig. 1). Following randomization, eight participants withdrew or failed to begin their assigned treatments (1 in MBSR + SEI, 4 in SEI, and 3 in MBSR) and eight attended fewer than 3 treatment sessions (1 in MBSR + SEI, 4 in SEI, and 3 in MBSR). Of the participants who received the treatment (“completers” who attended at least 50% of sessions; Santorelli & Kabat-Zinn, 2012), 92% of MBSR + SEI (11 of 12), 100% of MBSR (12 of 12), and 77% of SEI (10 of 13) participants completed the 6-week and 12-week assessments. Completers and non-completers did not differ by treatment group or by gender, age, education, or baseline BMI (all ps N .05).
3.2. Sample characteristics Participants were mostly female (98%), middle aged (M = 45.4 years, SD = 10.4), college educated (M = 16.7 years, SD = 2.4), and overweight/obese (M BMI = 35.0 kg/m2, SD = 9.0, range 23.9 to 60.0). Ethnic background was diverse, with 41% Caucasian, 37% African American, 16% Hispanic, and 6% other.
3.3.2. Stress eating Repeated measures ANOVA indicated a significant main effect of time (F(2,24) = 18.02, p b .001). The main effect of group and the time by group interaction were non-significant. As displayed in Fig. 3, stress eating scores increased (indicating better functioning/improvement) in all groups with a large effect, with the greatest improvement in the MBSR + SEI group. 3.3.3. Weight Repeated measures ANOVA indicated a significant main effect of time (F(2, 29) = 5.04, p = .01), but non-significant main effect of group and time by group interaction. As displayed in Fig. 4, in the MBSR + SEI and SEI groups, weights decreased across the course of the study. For the MBSR group, weight initially increased slightly from pre- to post-treatment, before returning to baseline levels at follow up. 3.3.4. Testing the combination intervention Effects of MBSR + SEI on Stress Eating, Perceived Stress, and Weight Scores for MBSR + SEI participants on each outcome measure are shown in Table 2. Repeated measures ANOVA indicated significantly decreased perceived stress (F(2,6) = 5.71, p = .04) and significantly
Fig. 2. PSS scores by treatment condition.
Fig. 4. Weight loss by treatment condition.
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Table 2 MBSR + SEI scores over time.
EADES-SE⁎ PSS⁎ Weight
Baseline
Post-treatment
Follow-up
Partial eta2
60.10 (18.34) 21.40 (7.97) 211.82 (55.52)
79.18 (10.33) 13.70 (8.11) 212.00 (58.48)
85.00 (8.31) 11.67 (7.09) 210.23 (57.58)
.83 .66 .16
EADES-SE, Eating and Appraisal Due to Emotions and Stress Questionnaire-Emotion and Stress-Related Eating scale, higher scores indicate better functioning. PSS, Perceived Stress Scale, higher scores indicate more stress. ⁎ p b .05 in repeated measures ANOVA.
decreased stress/emotional eating (F(2,7) = 17.39, p = .002), Although a modest weight loss was also achieved, it was not statistically significant (p = .47). There was, however, a moderate effect size for weight loss in this group. 3.4. Intention-to-treat analysis. All group comparison analyses were also completed with an intention-to-treat method using last observation carried forward to account for missing data. The same significance patterns were found in each analysis. 3.5. Feasibility and integrity of the interventions We evaluated the feasibility of the intervention through several means: Evaluating the recruitment rate, evaluating the participant dropout rate, evaluating participant-reported use of learned strategies, and noting informal participant feedback and requests. The recruitment rate for this study was very high. We had a strong response (123 calls) to recruitment efforts. Of those who indicated interest, 40% met the criteria for study entry, indicating that recruiting for this study is highly feasible. Next, the drop-out rate was low (14%), which is superior to or equal to other mindfulness and disordered eating interventions (Katterman, Kleinman, Hood, Nackers, & Corsica, 2014). Although we were unable to test group differences due to small sample sizes, the MBSR + SEI group had fewer drop-outs than the MBSR or SEI groups (1 vs 3 vs 4, respectively), indicating that participants may have found it more acceptable, useful, and/or enjoyable. At the end of the study, participants completed a questionnaire about their use of intervention strategies. The majority of participants (90%) indicated that they continued to use the intervention components at least once a week. Participants were also asked what they would recommend changing in a future intervention. The only substantive suggestion for improvement, recommended by several participants, was for a longer course of treatment and follow-up. Anecdotally, participants reported finding the intervention acceptable and useful. Treatment integrity was evaluated by comparing the outcome of the intervention across both group leaders. There were no significant group differences in any treatment outcomes based on group leader (p N .05), indicating that the manualized intervention was reasonably standardized and delivered and that the effect of the intervention was not dependent on therapist characteristics. 4. Discussion Approximately 50% of people report engaging in stress-related overeating. With perceived stress levels higher than ever before, stresseating constitutes a very real threat to effective weight management. Few studies have developed and tested treatments aimed specifically at reducing stress-related eating, and none have compared the effects of targeting different mechanisms thought to contribute to stress eating (high perceived stress vs the actual behavior of choosing and eating hedonically pleasing foods). This intervention was developed in order to begin to identify the components of stress-eating that are optimal targets for intervention (i.e. stress vs. eating in response to stress), and
thus, begin to identify mechanisms of change in the treatment of stress eating. Our main goal was to compare the effectiveness of intervention components that directly and indirectly targeted stress and stress-related eating. We theorized that targeting overall stress with a mindfulnessbased stress reduction (MBSR) intervention may reduce stress-eating behaviors without specifically targeting those behaviors, but rather, by reducing perceived stress through increased mindfulness. We compared MBSR with a focused stress-eating intervention developed for this study that directly addressed the problem of eating in reaction to stress through cognitive and behavioral strategies. This intervention included education on the psychological and biological impact of stresseating, improving nutrition, reducing intake of sugar and processed foods (that tend to promote continued reliance on eating to cope with stress), developing alternate coping strategies, and repeated and structured in vivo exposure to “problem” foods while under stress. The last component was unique in teaching participants how, under stressful circumstances, to learn to resist eating convenient, tempting, but low quality foods and learn new ways of responding. Lastly, we hypothesized that combining the mindfulness and stresseating intervention would more comprehensively address stress-eating by tackling two different components of the experience, and prove to be of superior effectiveness in addressing stress-eating, perceived stress and possibly even weight (although as a six week study that did not specifically target weight, that expectation was not high). The study had three main findings. First, all three interventions resulted in significant improvement in the target variables of perceived stress and stress eating. In addition, these effects appear to have been maintained and in some cases, even improved over time, as further reductions were apparent at follow-up. Second, while all groups exhibited improvements in symptoms, the combination intervention appeared to result in the best overall outcomes at post treatment, suggesting that combining both a mindfulness-based treatment for general stress reduction and a cognitive behavioral treatment targeting stress-eating behavior directly may be the most effective strategy for reducing stress and stress-eating. Third, we found that the mindfulness and stresseating intervention components as developed and executed were feasible and standardizable. Anecdotally, in verbal discussions following the completion of the groups, most treatment completers indicated that the interventions were highly acceptable and that they continued to use the strategies they had learned. The main strength of this study was in developing and executing an intervention that specifically targets stress eating and in the comparative assessment of the impact of different intervention components on stress-eating that had, in previous studies of emotional and binge eating, been difficult to disentangle. Other interventions (see Katterman et al., 2014 for a recent review) have used mindfulness successfully in the treatment of binge eating and emotional eating, and have occasionally been useful in weight loss. However, because the mindfulness interventions were adapted by adding nutritional and/or eating management components, it is unclear whether mindfulness or eating management contributed to the success. In addition, because of the lack of control or comparison groups, it is unclear whether this is a general therapeutic attention finding. The interventions tested in this study differed in that they focused individually on the two different components of the stress-eating experience (overall stress versus the stresseating thoughts and behaviors) and also combined the components. Thus, we had three comparison groups, each with the same leader, enabling us to rule out attention and general intervention effects. Lastly, to our knowledge, this is the first intervention to use an exposure-based treatment component as part of the cognitive-behavioral treatment of stress-eating, a component that we believe enhances applicability to real-world stress eating. The main limitations of this pilot study were related to small sample size, participant drop out, and the almost entirely female composition of the sample, all of which should be addressed in future studies to improve
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statistical power and generalizability. In addition, closer examination of participants’ daily food choices, caloric and macronutrient intake, waist circumference, and biological indicators of stress (e.g. cortisol levels) would be useful in order to assess the dietary and physiological impact of the different interventions. This would contribute to a further understanding of the mechanisms of change in the treatment of stress-eating. However, our findings suggest that an approach that addresses both perceived stress through mindfulness and maladaptive eating behaviors through exposure based cognitive behavioral treatment has the potential to show the greatest impact on an eating and weight difficulty that is reported by nearly half of the population. Role of funding sources Funding for this study was provided by the Roberts Fund. The Roberts Fund had no role in the study design, collection, analysis or interpretation of the data, writing the manuscript, or the decision to submit the paper for publication. Contributors Authors 1 and 2 designed the study and wrote the protocol. Authors 1, 2, 3, 4, and 5 conducted literature searches and provided summaries of previous research studies. Author 2 conducted the statistical analysis. Author 1 wrote the first draft of the manuscript and all authors contributed to and have approved the final manuscript. Conflict of interest All authors declare that they have no conflicts of interest.
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