Outcomes Research in Review

Can Mindfulness Components Added To A Diet-Exercise Program Improve Weight Loss Outcomes?

Daubenmier J, Moran PJ, Kristeller J, et al. Effects of a mindfulness-based weight loss intervention in adults with obesity: a randomized clinical trial. Obesity 2016;24:794–804.


 

References

Study Overview

Objective. To determine whether weight loss and cardiometabolic risk factors are improved when mindfulness training is added to a diet-exercise program.

Design. 2-arm randomized controlled trial.

Setting and participants . Study participants were recruited through fliers, newspaper advertisements, online postings, and referrals at University of California, San Francisco clinics, and were enrolled from July 2009 to February 2012. Inclusion criteria were body mass index (BMI) between 30 and 45.9, abdominal obesity (waist circumference > 102 cm for men and > 88 cm for women), and age 18 or older. Exclusion criteria were current involvement with diet program or diet mediation, diabetes mellitus, fasting glucose ≥ 126 mg/dL, or hemoglobin A1c (HbA1C) between 6.0% and 6.5% with abnormal oral glucose tolerance test. Participants were randomized in a 1:1 ratio to one of 2 weight loss program arms using a computer-generated randomization sequence.

Intervention. In both arms, participants received general diet and exercise guidelines prescribing healthy eating and frequent exercise delivered in 16 sessions lasting 2 to 2½ hours and one all-day session over 5.5 months. Participants in the mindfulness intervention additionally received mindfulness training for eating, physical activity, and stress management from mindfulness mediation instructors and a registered dietician. They also followed guidelines at home, which included practicing meditation for up to 30 minutes 6 days a week, mini-meditations, and eating mindfully. To control for the activities and attention inherent in the mindfulness arm (eg, social support, expectation of benefit, snacks provided during mindful eating exercises, at home practice), the control arm was an “active control” and included additional nutritional and physical activity information, snacks, strength training, home activities, conversations about society and weight loss, and low-dose progressive muscle relaxation and cognitive-behavioral training. Active control materials were delivered by one of 3 registered dieticians.

Main outcomes measures . The primary outcome was 18-month weight change. Participants’ weight, height, blood pressure, and weight circumference were measured at baseline and 3, 6, 12, and 18 months between 8 am and 10 am. Measurements were taken under fasting conditions and by arm-blinded staff. Blood samples were taken to assess secondary outcome changes in glucose, lipid, HbA1C, insulin, and C-reactive protein. Researchers also collected anonymous qualitative feedback from participants and supervisors to do a secondary analysis assessing differences in effectiveness and helpfulness of mindfulness teachings among instructors.

Main results . Of the potential participants that contacted the study team in response to recruitment efforts ( n = 1485), 216 were fully eligible based on criteria and a screening visit. Participants that consented to participate ( n = 194) were randomized. Participants across both groups were predominantly female, of European ethnic origin, and similar in age: mindfulness group, 47.2 years (13.0) and active control group, 47.8 years (12.4). At baseline, the mindfulness and active control arms had average BMIs of 35.4 (3.5) and 35.6 (3.8), respectively. Baseline characteristics, session attendance, and 18-month retention were similar for both arms. Participants in the mindfulness arm reported completing 70% (2.1 hours per week, SD = 1.2) of the recommended meditation time and eating 57% (SD = 29) of meals mindfully.

Weight loss outcomes between groups favored the mindfulness arms, but results were not significant. The largest difference of –1.9 kg (95% CI –4.5 to 0.8; P = 0.17) was at 12 months. The difference persisted at 18 months with –1.7 kg (95% CI –4.7 to 1.2 kg; P = 0.24). The mindfulness arm lost 4.2 kg (95% CI –6.2 to 2.2 kg) while the active control arm lost 2.4 kg (95% CI –4.5 to –0.3 kg).

Cardiometabolic outcomes at 12 months showed group differences in fasting glucose that favored the mindfulness arm, –3.1 mg/dL (95% CI 26.3 to 0.1; P = 0.06), while there was a significant group difference at 18 months, –4.1 mg/dL (95% CI –7.3 to –0.9; P = 0.01). Data at 18-months showed that normal glucose changed minimally in the mindfulness arm, –0.31 mg/dL (95% CI –2.5 to 1.9), but increased in the active control arm 3.8 mg/dL (95% CI 1.5 to 6.1). Other cardiometabolic outcomes (ie, triglyceride/HDL ratio and triglycerides) showed significance at 12 months, favoring the mindfulness arm, but not at 18 months. Although not all were statistically significant, 9 of 11 outcomes favored the mindfulness arm at 18 months.

Significant interactions ( P < 0.05) were found between arm and enrollment rounds categorized by mindfulness instructor on weight, BMI, fasting glucose, homeostatic homeostasis model assessment of insulin resistance (defined as [glucose x insulin/{40 × 33.25}]), and HbA1c, with a marginally significant effect for waist circumference ( P = 0.08). Qualitative feedback on mindfulness instructors showed that in the group with a lowly rated instructor, participants lost less weight at 18 months (–2.0 kg [95% CI –4.7 to 0.7]), compared to participants in groups with highly rated instructors (–6.3 kg [95% CI –9.1 to –3.6]; P = 0.02). Similar trends followed for reductions in BMI and waist circumference.

Conclusions. With regard to weight loss outcomes, a mindfulness-enhanced diet-exercise program and an active control arm did not show substantial differences. Some evidence, however, suggests modest benefit of added mindfulness components, which may lead to long-term maintenance of fasting glucose levels and improved atherogenic lipid profiles.

Commentary

Mindfulness, or nonjudgmental focus on the present moment, has been utilized by many interventions targeted at self-regulated behavior [1]. Mindfulness interventions aim to promote healthy behavior changes by encouraging careful monitoring of behavior reactivity. Weight loss and weight loss maintenance have been of particular interest with this approach because mindfulness-based interventions may promote long-term maintenance of weight loss [2]. This maintenance is achieved through a focus on modifying health behaviors, rather than a focus on weight loss alone [3]. Mindfulness has been incorporated into weight loss interventions through yoga practices [4] and mindfulness meditation [5].

Several studies have explored the relationship between mindfulness and weight loss in various populations, highlighting mindfulness’s role in weight loss and behavior change. Most notably, mindfulness interventions have shown improvements in fasting glucose levels [6], psychological distress [7], self-efficacy, weight loss, eating behaviors, and physical activity [8–10]. Despite being well designed, this study by Daubenmier et al did not find significant changes in weight loss. However, secondary outcomes related to weight, metabolic, syndrome, and cardiovascular risk showed modest improvements with mindfulness. These results may correlate to previous findings showing that lifestyle changes many not result in weight loss but can reverse or reduce disorders related to obesity [11].

The study was strengthened by randomization, intention-to-treat analysis, objective measures by arm-blinded staff, standardized measuring conditions, balanced participant allocation to each arm, 1-year follow-up, and qualitative feedback on instructors to assess whether weight loss may be instructor-dependent. In addition, the authors made an effort to mask their intention to test the effects of a mindfulness-enhanced intervention. They designed a rigorous active control intervention arm by controlling for attention, social support, expectations of benefit, diet-exercise guidelines, and elements of a mindfulness approach to stress management. An additional strength included a cost-analysis of adding mindfulness components. The generalizability of the results may be limited as the study population were predominantly white females and most had a bachelor’s degree. The study sample was also disproportionately menopausal women, a group that especially struggles with weight loss. This demographic factor may be responsible for the lack of significant weight loss. Other limitations of this study include participant dropout and variability between instructor styles, although the latter was explored in a secondary analysis of weight loss differences between instructors.

The researchers discussed how the active control intervention arm may have contributed to the lack of significant weight loss difference between groups. The researchers also highlighted that participants randomized to the mindfulness arm that were not interested in mindfulness practices may have benefitted less than those who were interested. This combined with the modest diet and exercise components of the intervention may also explain the lack of significance in results. It may also explain why some outcomes were significant at earlier months but attenuated by 18 months. Future studies should assess incorporating more intense exercise and diet approaches, as well as continuous contact throughout the 18-month time period.

Applications for Clinical Practice

This study demonstrated that mindfulness components added to a diet-exercise program can be helpful in promoting metabolic changes but not necessarily weight loss. Since metabolic changes can be protective against morbidities (eg, type 2 diabetes), mindfulness can be a powerful and cost-effective approach within clinical practice. Mindfulness practices can also be easily implemented in various settings and with diverse populations. Future studies should explore adding mindfulness components to more intensive weight loss interventions. Providers and health care settings should consider incorporating mindfulness practices into weight management counseling and programs.

—Michelle J. Williamson and Katrina F. Mateo, MPH

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