Abstract
Objective:
This study examined the feasibility and comparison of two styles of yoga within the context of a behavioral weight loss intervention (SBWI).
Methods:
Fifty adults with obesity (BMI: 31.3±3.8 kg/m2) participated in this 6-month study that included a SBWI and a calorie and fat-reduced diet. Randomization was to restorative Hatha (SBWI+RES) or Vinyasa (SBWI+VIN) yoga. Yoga was prescribed to increase from 20 to 40 to 60 minutes per session across the intervention. Weight was assessed at baseline and 6-months. Perceptions of yoga were assessed at the completion of the intervention.
Results:
Adjusted weight loss was −3.4 (95% CI: −6.4, −0.5) kg in SBWI+RES and −3.8 (95% CI: −6.8, −0.9) kg in SBWI+VIN (p<0.001), with no difference between groups. 74.4% reported that they would continue participation in yoga after the SBWI. Session duration was a barrier as yoga increased from 20 to 40 to 60 minutes per day, with 0%, 7.5%, 48.8% reporting this barrier, respectively.
Conclusions:
Among adults with obesity, yoga participation, within the context of a SBWI appears to be feasible, with weight loss not differing by style of yoga. Progressing to 60 minutes per session appears to be a barrier to engagement in yoga in this population.
Keywords: obesity, physical activity, weight loss
Introduction
In the United States, prevalence data indicate that approximately 70 percent of adults are classified as overweight (Body Mass Index: ≥25 kg/m2) and approximately 35 percent classified as obese (BMI ≥30 kg/m2).(1, 2) Excess body weight is associated with numerous chronic health conditions that include cardiovascular disease, diabetes, cancer, musculoskeletal conditions, reduced health-related quality of life, and other negative health-related conditions.(3, 4) Weight loss has been shown to reduce the risk for many of these conditions, and if already present, weight loss can improve these conditions.(3)
The foundation of weight loss interventions is behavioral counseling that is coupled with reduced energy intake, in the form of a moderate calorie restricted diet, and increased energy expenditure, in the form of physical activity and structured exercise. In combination, these approaches can result in clinically significant weight loss within a 6-month intervention, and weight loss can be sustained long-term with continued engagement in an appropriate level of energy intake and participation in physical activity.(3)
Physical activity is an important lifestyle factor for weight loss and maintenance. When coupled with a dietary intervention, physical activity can increase initial weight loss by approximately 20 percent compared to weight loss achieved with the same dietary intervention alone.(5) Moreover, physical activity is associated with improved weight loss maintenance and attenuation of weight regain.(6) Most research on the role of physical activity for weight control has focused primarily on aerobic modes of physical activity such as brisk walking, with some additional research focused on weight training. However, other forms of physical activity (e.g., yoga) may be effective for weight loss that warrant further examination.
Yoga is a broad term used to describe mental, physical and spiritual disciplines, which originated in ancient India. Yoga may be beneficial for treating obesity because of its potential to decrease stress,(7, 8) mitigate pain,(9, 10, 11) enhance mood and diminish depression,(12, 13) enhance sleep,(14, 15) and increase energy expenditure.(16, 17) These benefits may provide some insight into the pathways by which yoga has been shown to be associated with lower weight and BMI.(18, 19, 20, 21) However, few studies have examined the feasibility and effect of including yoga within the context of a standard behavioral weight loss intervention (SBWI). Moreover, few studies have examined whether different styles of yoga, particularly within the context of a SBWI, may be more feasible and provide a similar effect on weight loss.
The aim of this study was to conduct both a feasibility study and to complete an initial comparison of two styles of yoga within the context of a 6-month SBWI. Yoga styles included: 1) restorative Hatha style of yoga that focuses mostly on poses (asanas) for relaxation and the holding of postures (SBWI+RES),(22) and 2) Vinyasa yoga that is a more rigorous style of yoga and involves the individual moving continuously through poses versus holding poses (SBWI+VIN).(22, 23) Outcomes of interest included engagement in yoga and physical activity, change in dietary intake, weight loss, cardiorespiratory fitness, and perceptions of yoga participation in adults with overweight or obesity.
Methods
Study Design
This study used a randomized design with assessments occurring at baseline and following a 6-month intervention period. Randomization was to either SBWI+RES or SBWI+VIN. Randomization was blocked on gender (male or female) and race (white or non-white) using sequential randomization conducted by the Principal Investigator with the assistance of the data manager.
Subjects
Fifty subjects were recruited to participate in this study starting in May 2018 with final data collection completed December 2018. Recruitment methods included research registries, mass mailings of a recruitment postcard, and electronic distribution of a recruitment flier. Interested participants were screened for initial eligibility by telephone, and those meeting initial eligibility criteria were invited to a study orientation session. This orientation session involved one of the investigators explaining the details of the study and allowing interested individuals to have their questions regarding study participation answered. Written informed consent was obtained prior to proceeding with any additional study procedures. This study was conducted at the University of Pittsburgh (Pittsburgh, PA) and procedures were approved by the University of Pittsburgh Human Research Protection Office and Institutional Review Board.
Eligibility criteria included 18-60 years of age and BMI of 25 to <40 kg/m2. Individuals were deemed to be ineligible if they 1) self-reported moderate-to-vigorous exercise on >3 days per week or a total of >60 minutes per week over the past 3 months; 2) engaged in any style of yoga on an average of at least 1 day per week over the past 3 months; 3) reported weight loss of >3% or participating in a weight reduction diet in the past 3 months; 4) female and pregnant or breastfeeding, or reporting a planned pregnancy during the study period; 5) had a history of bariatric surgery; 6) reported a current medical condition or treatment for a medical condition that could affect body weight; 7) current congestive heart failure, angina, uncontrolled arrhythmia, symptoms indicative of an increased acute risk for a cardiovascular event, prior myocardial infarction, coronary artery bypass grafting or angioplasty, conditions requiring chronic anticoagulation; 8) (i.e. recent or recurrent DVT); 9) resting systolic blood pressure of >160 mmHg or resting diastolic blood pressure of >100 mmHg; 10) presence of an eating disorder that would contraindicate weight loss or physical activity; 11) history of alcohol or substance abuse; 12) currently treated for psychological issues (i.e., depression, bipolar disorder, etc.), taking psychotropic medications within the previous 12 months, or hospitalized for depression within the previous 5 years; or 13) reported plans to relocate to a location not accessible to the study site or having employment, personal, or travel commitments that prohibit attendance at scheduled intervention sessions or assessments.
Participants were paid an honorarium of $100 for completing the assessments following the 6-month intervention.
Intervention
The weight loss intervention included weekly group-based intervention sessions. These sessions were approximately 60 minutes in duration. This included 30 minutes dedicated to a discussion of behavioral strategies to enhance engagement in lifestyle factors to promote weight loss, and 30 minutes dedicated to a yoga session consistent with the randomized intervention assignment.
Diet:
Participants were prescribed an energy-restricted diet to facilitate weight loss. Dietary intake was prescribed between 1200 and 1800 kcal per day based on initial body weight. Meal plans were provided to assist in achieving the prescribed dietary goals. Participants were instructed to record their food intake in a diary that was returned weekly to the intervention staff for review.
Yoga Interventions:
There were common components included in both the SBWI+RES and SBWI+VIN yoga interventions. Both styles of yoga were prescribed for 5 days per week with duration progression from 20 minutes per day during weeks 1-8, to 40 minutes per day during weeks 9-16, and 60 minutes per day during weeks 17-24. One session per week was supervised and 4 were home-based. To facilitate engagement, there were foundation sessions to instruct on the poses (asanas) followed by progressive sessions to achieve the goal for each week. The poses allowed for modifications so that each participant could engage at their physical ability. To allow for standardization, custom videos were produced that were used during the supervised sessions, and the staff were also available at these sessions to assist participants with correct body positioning and appropriate modifications. These same videos were provided on tablets to participants to facilitate home-based yoga sessions. Participants were also provided with a yoga mat, block, and strap.
Yoga sessions were held separately for the SBWI+RES and SBWI+VIN interventions, and only the videos consistent with intervention randomization assignment were provided to individual participants for home use. The styles of yoga differed by intensity and how the poses were performed. SBWI+RES involved performing the poses in a manner that required a gradual transition from pose to pose, with each pose held for a short period prior to moving the next pose.(24) Conversely, SBWI+VIN involved performing the poses in a flow that moved from pose to pose as previously described.(25) The difference in yoga practices were designed to result in intensity of yoga to be greater in SBWI+VIN compared to SBWI+RES.
Outcome Measures
Outcomes at 6 months were conducted by staff who did not deliver the intervention.
Weight, Height, BMI:
Weight was measured at baseline and 6 months on a calibrated digital scale to the nearest 0.1 kg with participants clothed in a light-weight hospital gown. Height was measured at baseline using a stadiometer with shoes removed. Weight and height were used to compute BMI expressed as kg/m2.
Cardiorespiratory Fitness:
Cardiorespiratory fitness was assessed at baseline and 6 months using a submaximal graded exercise test on a treadmill with test termination occurring at 85% of age-predicted maximal heart rate [(220-age)*0.85] as previously reported.(26) Speed was held constant at 80.4 meters per minute, with grade starting at 0% and progressing in a stepped manner at 1% per minute. Oxygen consumption was measured continuously throughout the test using a calibrated metabolic cart.
Physical Activity:
Leisure-time physical activity was assessed using a questionnaire which assessed walking, climbing of stairs, and other forms of fitness, sport, or recreational activities as previously described.(27) This questionnaire was completed at baseline and following the 6-month intervention, and was scored to provide data on total physical activity per week (total kcal per week). In addition, the questionnaire was scored removing the climbing of stairs, with these data computed as kcal per week without flights and minutes per week without flights. Participants were also instructed to record their yoga participation in a diary that was returned to the investigators weekly.
Dietary Intake:
Dietary intake was assessed at baseline and 6 months using the Diet History Questionnaire (version 3; DHQIII) developed by the National Cancer Institute. This was completed online with participants queried regarding the types, amounts, and frequency of consumption of foods consumed over the prior month. This information was used within the DHQIII software to provide an estimate of daily energy intake and percent of calories consumed as carbohydrates, fat, and protein.
Perception of Yoga
At the conclusion of the intervention, subjects completed a brief questionnaire to evaluate 1) the perceived physical effort of the yoga, 2) whether the perceived effort was influenced by the individual poses or the transition between poses, 3) whether the duration of the yoga session was a barrier, 4) whether the participant reports their desire to continue yoga once the study has concluded.
Data Analysis
Intent-to-treat analyses were performed with all randomized participants were included in the analyses regardless of data completeness at 6-months (Tables 2 and 3). Missing data were assumed to be missing at random. Separate mixed-effects models with two time points were fit to the outcomes of yoga participation, physical activity, dietary intake, and eating behaviors measured at baseline and 6 months (see Table 2). Inferences were focused on the main effects of treatment group assignment, time, and the interaction effect between these two. Randomization stratification factors that included sex and race/ethnicity (white or non-white) were included as covariates. We also conducted separate general linear models to examine the change from baseline to 6 months for outcomes of weight, BMI, and cardiorespiratory fitness (see Table 3). For each of these models, the baseline value and randomization stratification factors that included sex and race/ethnicity (white or non-white) were included as covariates.
Table 2.
Physical activity and diet by intervention condition.
| Least-Squares Mean (95% CI) | P value | |||||
|---|---|---|---|---|---|---|
| Variable | Intervention Condition |
Baseline | 6 months | Group | Time | Group x Time |
| Yoga Participation (weekly diaries) | ||||||
| Days per Week | SBWI+RES | ----- | 2.7 (1.9, 3.5) | 0.4682 | ----- | ----- |
| SBWI+VIN | ----- | 2.4 (1.6, 3.2) | ||||
| Minutes per Day | SBWI+RES | ----- | 35.6 (32.9, 38.4) | 0.0118 | ----- | ----- |
| SBWI+VIN | ----- | 31.8 (29.1, 34.5) | ||||
| Total Minutes | SBWI+RES | ----- | 2104.7 (1455.4, 2753.9) | 0.2403 | ----- | ----- |
| SBWI+VIN | ----- | 1695.3 (1061.0, 2329.7) | ||||
| RPE | SBWI+RES | ----- | 11.1 (9.3, 13.0) | 0.0681 | ----- | ----- |
| SBWI+VIN | ----- | 9.3 (7.5, 11.0) | ||||
| Yoga Participation (questionnaire) | ||||||
| Yoga (minutes per week) | SBWI+RES | 1.3 (0, 7.9)* | 106.1 (66.6, 145.7) | 0.3050 | <0.0001 | 0.4510 |
| SBWI+VIN | 0 (0, 4.3)* | 81.2 (41.6, 120.7) | ||||
| Yoga (days per week) | SBWI+RES | 0 (0, 0.1)* | 2.1 (1.3, 2.9) | 0.6164 | <0.0001 | 0.7229 |
| SBWI+VIN | 0 (0, 0.1)* | 1.9 (1.1, 2.7) | ||||
| Physical Activity | ||||||
| Total Physical Activity (kcal per week) | SBWI+RES | 585.0 (386.8, 783.2) | 1189.1 (856.9, 1521.3) | 0.2366 | <0.0001 | 0.0462 |
| SBWI+VIN | 596.1 (403.1, 789.1) | 830.9 (497.5, 1164.4) | ||||
| Total Physical Activity (kcal per week without flights) | SBWI+RES | 292.3 (109.6, 474.9) | 877.1 (568.0, 1186.1) | 0.1877 | <0.0001 | 0.0178 |
| SBWI+VIN | 322.3 (144.5, 500.1) | 489.1 (178.6, 799.6) | ||||
| Total Physical Activity (minutes per week without flights) | SBWI+RES | 51.7 (15.1, 88.2) | 192.1 (124.8, 259.5) | 0.1187 | <0.0001 | 0.0288 |
| SBWI+VIN | 56.9 (81.2, 92.6) | 101.6 (34.7, 168.6) | ||||
| Dietary Intake | ||||||
| Total Calories (kcal/day) | SBWI+RES | 1502.7 (1075.9. 1929.5) | 1091.8 (787.9, 1395.7) | 0.8527 | 0.0005 | 0.9784 |
| SBWI+VIN | 1471.3 (1084.4, 1858.2) | 1054.3 (750.1, 1358.5) | ||||
| % Calories, Carbohydrates | SBWI+RES | 48.6 (44.5, 52.8) | 50.6 (46.4, 54.8) | 0.2153 | 0.0284 | 0.2762 |
| SBWI+VIN | 49.0 (44.9, 53.1) | 54.8 (50.4, 59.2) | ||||
| % Calories, Protein | SBWI+RES | 16.254 (14.437, 18.072) | 17.5 (15.8, 19.3) | 0.3839 | 0.2962 | 0.1786 |
| SBWI+VIN | 16.223 (14.449, 17.996) | 16.1 (14.3, 17.8) | ||||
| % Calories, Fat | SBWI+RES | 36.0 (32.8, 39.2) | 31.9 (28.9, 35.0) | 0. 4509 | 0.0002 | 0.3351 |
| SBWI+VIN | 36.3 (32.8, 39.2) | 29.6 (26.6, 32.8) | ||||
| Eating Behavior Inventory | SBWI+RES | 54.5 (50.6, 58.3) | 64.8 (61.0, 68.6) | 0.5246 | <0.001 | 0.6051 |
| SBWI+VIN | 54.9 (51.2, 58.6) | 66.6 (62.7, 70.5) | ||||
SBWI+RES: Standard Behavioral Weight Loss Intervention plus Restorative style of Hatha Yoga
SBWI+VIN: Standard Behavioral Weight Loss Intervention plus Vinyasa Yoga
Adjusted for gender and race.
Indicates that LSMEANs and 95% CI were truncated at 0.
Table 3.
Change in weight, BMI, and cardiorespiratory fitness by intervention condition.
| Mean (95% CI) | Least-Squares Mean (95% CI)* |
P value for comparison of change from baseline between SBWI+RES and SBWI+VIN |
|
|---|---|---|---|
| Baseline | Change from Baseline to 6 months | ||
| Weight, kg | |||
| SBWI+RES (N=25) | 87.3 (82.2, 92.4) | −3.4 (−6.4, −0.5) | 0.7883 |
| SBWI+VIN (N=25) | 88.4 (83.2, 93.5) | −3.8 (−6.8, −0.9) | |
| Weight change from baseline, % | |||
| SBWI+RES (N=25) | ----- | −3.8 (−7.0, −0.6) | 0.6585 |
| SBWI+VIN (N=25) | ----- | −4.5 (- 7.8, −1.3) | |
| Body mass index, kg/m2 | |||
| SBWI+RES (N=25) | 30.5 (29.0, 32.0) | −1.3 (−2.2, −0.3) | 0.8605 |
| SBWI+VIN (N=25) | 32.1 (30.6, 33.5) | −1.4 (−2.4, −0.4) | |
| Cardiorespiratory Fitness (ml/kg/min) | |||
| SBWI+RES (N=25) | 22.2 (20.3, 24.0) | 0.2 (−2.2, 2.6) | 0.7957 |
| SBWI+VIN (N=25) | 21.6 (19.8, 23.5) | −0.1 (−2.4, 2.1) | |
| Cardiorespiratory Fitness (termination time, minutes) | |||
| SBWI+RES (N=25) | 8.4 (7.2, 9.6) | 1.6 (0.5, 2.6) | 0.3802 |
| SBWI+VIN (N=25) | 8.0 (6.8, 9.2) | 1.1 (0.0, 2.1) | |
SBWI+RES: Standard Behavioral Weight Loss Intervention plus Restorative style of Hatha Yoga
SBWI+VIN: Standard Behavioral Weight Loss Intervention plus Vinyasa Yoga
Adjusted for baseline value, gender, and race.
Spearman correlation coefficients were used to examine the associations between weight loss and days and minutes of yoga participation. Perceptions of yoga participation are reported as the percent of study participants providing the response based on the number of participants completing the questionnaire.
Analyses were conducted using SAS version 9.4 (SAS Institute, Cary, NC). The type I error rate was fixed at 0.05.
Sample Size Determination
This was primarily designed as a feasibility study, which is the intent of the R34 program announcement (PAR-14-182) under which this study received funding support from the National Institutes of Health. Given this focus, the intent was to show feasibility to conduct the proposed recruitment, outcome assessments, and intervention. A power analysis was conducted to provide estimates with desirable precision to inform a larger randomized clinical trial. This power analysis demonstrated the need for 22 participants per intervention condition, and allowing for an estimated 10 percent attrition, this resulted in a total sample size of 50 participants, with 25 randomized to each intervention.
Results
This study screened 445 individuals to identify 50 participants who were randomized to SBWI+RES (N=25) or SBWI+VIN (N=25) (Figure 1). Descriptive characteristics are shown in Table 1. Retention of participants across the intervention was 86% (Figure 1, 92% in SBWI+RES, 80% in SBWI+VIN). There were no serious adverse events reported in this study.
Figure 1.
Consort diagram.
*SBWI+RES: Standard behavioral weight loss intervention + Restorative Style of Yoga
**SBWI+VIN: Standard behavioral weight loss intervention + Vinyasa Style of Yoga
Table 1.
Baseline characteristics of participants by intervention condition.
| Total (N=50) |
SBWI+RES (N=25) |
SBWI+VIN (N=25) |
|
|---|---|---|---|
| *Age, years | 45.8±9.5 | 45.0±9.6 | 46.5±9.7 |
| *Weight, kg | 87.8±12.9 | 87.3±12.3 | 88.4±13.7 |
| *Body mass index, kg/m2 | 31.3±3.8 | 30.5±3.7 | 32.1±3.8 |
| Gender | |||
| Male [N (%)] | 8 (16.0) | 4 (16.0) | 4 (16.0) |
| Female [N (%)] | 42 (84.0) | 21 (84.0) | 21 (84.0) |
| Race | |||
| White [N (%)] | 41 (82.0) | 21 (84.0) | 20 (80.0) |
| Non-White [N (%)] | 9 (18.0) | 4 (16.0) | 5 (20.0) |
| Hispanic/Latino | |||
| Yes [N (%)] | 2 (4.0) | 1 (4.0) | 1 (4.0) |
| No [N (%)] | 48 (96.0) | 24 (96.0) | 24 (96.0) |
Mean ± Standard Deviation
SBWI+RES: Standard Behavioral Weight Loss Intervention plus Restorative style of Hatha Yoga
SBWI+VIN: Standard Behavioral Weight Loss Intervention plus Vinyasa Yoga
Yoga and Total Physical Activity
Yoga engagement was assessed using data from the self-reported weekly diaries (Table 2.) Days per week of yoga participation was 2.7 (95% CI: 1.9, 3.5) in SBWI+RES and 2.4 (95% CI: 1.6, 3.2) in SBWI+VIN (p=0.4682). Total minutes of yoga across the intervention was 2104.7 (95% CI: 1455.4, 2753.9) in SBWI+RES and 1695.3 (95% CI: 1061.0, 2329.7) in SBWI+VIN (p=0.2403), which corresponds to 35.6 (95% CI: 32.9, 38.4) minutes per day in SBWI+RES and 31.8 (95% CI: 29.1, 34.5) minutes per day in SBWI+VIN (p=0.0118) for days that yoga was performed. Self-reported rating of perceived exertion (RPE), which is a perception of yoga intensity, across all of the yoga sessions was 11.1 (95% CI: 9.3, 13.0) in SBWI+RES and 9.3 (95% CI: 7.5, 11.0 in SBWI+VIN (p=0.0681).
Yoga was also assessed on the physical activity questionnaire completed at baseline and 6 months (Table 2). Both minutes of yoga per week and days per week of yoga increased from baseline to 6 months (p<0.0001). There was no significant difference between SBWI+RES and SBWI+VIN for the change in either minutes or days of yoga per week from baseline to 6 months.
Total physical activity data assessed by questionnaire are presented in Table 2. Total kcal per week (kcal/week) significantly increased from baseline to 6 months (p<0.0001), with SBWI+RES increasing from 585.0 (95% CI: 386.8, 78.2) kcal per week to 1189.1 (95% CI: 856.9, 1521.3) kcal per week and SBWI+VIN increasing from 596.1 (95% CI: 403.1, 789.1) kcal/week to 830.9 (95% CI: 497.5, 1164.4) kcal/week (p-value for Group X Time = 0.0462). A similar pattern was observed for kcal/week without flights of stairs climbed (p-value for Time <0.0001; p-value for Group X Time = 0.0178) and minutes per week (p-value for Time <0.0001; p-value for Group X Time = 0.0288).
Dietary Intake and Eating Behaviors
Dietary intake data are provided in Table 2. There was a significant decrease in total kcal/day from baseline to 6 months (p=0.0005), with no significant difference for the pattern of change in total kcal/day between SBWI+RES and SBWI+VIN (p-value for Group X Time = 0.9784). Percent of calories consumed as carbohydrates increased (p=0.0284) and percent of calories consumed as fat decreased (p=0.0002) from baseline to 6 months, with the pattern of change not differing between SBWI+RES and SBWI+VIN. There was no significant change in the percent of calories consumed as protein from baseline to 6 months. Moreover, the score on the Eating Behavior Inventory questionnaire increased from baseline to 6 months (p<0.0001), with no significant difference in the pattern of change between SBWI+RES and SBWI+VIN (p-value for Group X Time = 0.6051).
Weight and BMI
Weight decreased in both SBWI+RES and SBWI+VIN (Time p < 0.0001), with no difference for the change in weight between intervention conditions (Group X Time p=0.8116) (Table 3). Weight change adjusted for baseline weight, gender, and race was −3.4 (95% CI: −6.4, −0.5) kg for SBWI+RES and −3.8 (95% CI: −6.8, −.09) kg for SBWI+VIN. A similar pattern was observed for analysis of percent weight change and BMI (Table 3).
Weight loss in SBWI+RES was significantly associated with total days of yoga participation (r=0.5103, p=0.0129) and total minutes of yoga participation (r=0.4889, p=0.0179) across the 6-month intervention period. Similar results were observed in SBWI+VIN with both total days of yoga participation (r=0.5527, p=0.0115) and total minutes of yoga participation (r=0.5819, p=0.0071) across the 6 month intervention period associated with weight loss.
Cardiorespiratory Fitness
There was a non-significant change in cardiorespiratory fitness, measured as oxygen consumption (ml/kg/min) across the intervention with no difference between the intervention conditions (Group X Time p=0.7957). However, when assessed using termination time for the graded exercise test, there was a significant increase across the intervention period, with no difference between the intervention conditions (Group: p=0.3802) (Table 3).
Perceptions of the Yoga Intervention
Perceptions of the yoga intervention are shown in Table 4. The majority of participants in SBWI+RES perceived the yoga to be similar to the intensity of a brisk walk (43.5%), whereas the majority of participants in SBWI+VIN perceived the intensity of yoga to be more than a brisk walk (65.0%). For SBWI+RES, 87.0% reported that the perceived effort was mostly a result of holding the yoga poses, with 65% of participants in SBWI+VIN reporting that that perceived effort was mostly influenced by transition between yoga poses. In response to whether the duration of the yoga sessions was a barrier to participation, overall 92.8%, 55.0%, and 12.2% of participants indicated that sessions of 20, 40, and 60 minutes were mostly/definitely not a barrier to their participation. Regarding future participation in yoga following this 6-month intervention, 65.2% in SBWI+RES and 85.0% in SBWI+VIN reported that they definitely planned on continuing participation in yoga.
Table 4.
Perceptions of yoga participation.
| Parameter/ Question | Responses | SBWI+RES (N=23) |
SBWI+VIN (N=20) |
|---|---|---|---|
| Perceived effort exerted to perform the yoga | The effort was about the same effort that I would exert when taking a brisk walk. | 43.5% | 25.0% |
| The effort was more effort than I would exert when taking a brisk walk. | 26.1% | 65.0% | |
| The effort was less effort than I would exert when taking a brisk walk. | 30.4% | 10.0% | |
| Perception of factor(s) that influenced the effort exerted when performing yoga | The effort was mostly influenced by transitioning from yoga pose to yoga pose. | 0% | 5.0% |
| The effort was mostly influenced by holding the various yoga poses. | 87% | 30.0% | |
| The effort was equally influenced by transitioning from yoga pose to yoga pose, and by holding the various yoga poses. | 13% | 65.0% | |
| Performing yoga for 20 minutes per day was a barrier. | This duration of Yoga definitely was not a significant barrier to my Yoga participation. | 86.4% | 85.0% |
| This duration of Yoga mostly was not a significant barrier to my Yoga participation. | 4.5% | 10.0% | |
| This duration of Yoga sometimes was and sometimes was not a barrier to my Yoga Participation. | 9.1% | 5.0% | |
| This duration of Yoga mostly was a significant barrier to my Yoga participation. | 0% | 0% | |
| This duration of Yoga definitely was a significant barrier to my Yoga participation. | 0% | 0% | |
| Performing yoga for 40 minutes per day was a barrier. | This duration of Yoga definitely was not a significant barrier to my Yoga participation. | 33.3% | 15.8% |
| This duration of Yoga mostly was not a significant barrier to my Yoga participation. | 33.3% | 26.3% | |
| This duration of Yoga sometimes was and sometimes was not a barrier to my Yoga Participation. | 23.8% | 52.6% | |
| This duration of Yoga mostly was a significant barrier to my Yoga participation. | 9.5% | 5.3% | |
| This duration of Yoga definitely was a significant barrier to my Yoga participation. | 0% | 0% | |
| Performing yoga for 60 minutes per day was a barrier. | This duration of Yoga definitely was not a significant barrier to my Yoga participation. | 13.0% | 0% |
| This duration of Yoga mostly was not a significant barrier to my Yoga participation. | 4.3% | 5.6% | |
| This duration of Yoga sometimes was and sometimes was not a barrier to my Yoga Participation. | 34.8% | 44.4% | |
| This duration of Yoga mostly was a significant barrier to my Yoga participation. | 17.4% | 16.7% | |
| This duration of Yoga definitely was a significant barrier to my Yoga participation. | 30.4% | 33.3% | |
| Future participation in yoga once this study has ended. | I definitely plan on continuing my participation in yoga. | 65.2% | 85.0% |
| I may continue my participation in yoga. | 30.4% | 0% | |
| I am unsure if I will continue my participation in yoga. | 4.3% | 15.0% | |
| I may not continue my participation in yoga. | 0% | 0% | |
| I definitely do not plan on continuing my participation in yoga. | 0% | 0% |
Discussion
This study is one of the few to report on the inclusion of yoga within the context of a SBWI in adults with overweight or obesity. Results support that adults with overweight or obesity, who were not currently participating in yoga were able to initiate and engage in either style of yoga within the context of this SBWI, and that engagement in yoga was associated with greater weight loss across the 6 month intervention. However, weight loss did not differ between participants randomized to SBWI+RES versus SBWI+VIN.
The results of this study are important due to the current lack of data to support yoga across the spectrum of health-related outcomes, which includes obesity. The 2018 Physical Activity Guidelines Advisory Committee found that there was insufficient evidence available to determine the relationship between yoga and indicators of health risk progression, which included BMI.(28) Therefore, the need to conduct systematic and coordinated randomized controlled trials on the health effects of yoga was recommended, and this current study focused on obesity. An additional review emphasized the need for more rigorous research and well‐designed trials to evaluate yoga’s long-term impacts.(29) The current study used a randomized design with measures completed at both pre- and post-intervention, which may contribute to a higher degree of scientific rigor compared to other studies of yoga and obesity.
While this study resulted in significant weight loss, the weight loss appears to be less than what is typically observed in other SBWIs that were 6 months in duration.(30, 31) It is unclear why the weight loss in this study that combined a SBWI with yoga was less than what is typically observed. Hypotheses that may warrant examination are whether the energy expenditure from yoga blunted the weight loss compared to other forms of physical activity that are typically included in a SBWI, whether the yoga resulted in either an intentional or unintentional compensatory dietary response, or whether there was an unknown impact on biological or psychosocial factors that impacted the weight loss response. These hypotheses, and others, warrant further investigation. Moreover, the results of this study warrant replication in future investigations.
This was a feasibility study aimed to examine the ability of adults with obesity to engage in yoga, while also partaking in a SBWI. This study also examined whether various styles of yoga differed among measures of weight loss and cardiorespiratory fitness, however, no differences were observed between these conditions. These results are somewhat surprising given the current data in the literature, while limited, appear to support that energy expenditure is greater in Vinyasa yoga compared to restorative style of yoga. A restorative style of hatha yoga has been shown to result in energy expenditure of approximately 2.5 METS (metabolic equivalency task),(24) whereas Vinyasa yoga is approximately 4.0 METS of energy expenditure.(25) Others have reported that the faster tempo of the yoga practice, which may be similar to Vinyasa, results in a greater energy expenditure compared to slower tempos of yoga.(32) Given the potential for a higher intensity with Vinyasa, this would infer a potential greater energy expenditure resulting in greater weight loss and the higher intensity might also result in greater improvements in cardiorespiratory fitness. However, these findings do not support this assumption. This may be a result of the 6 month duration of this study or an inadequate amount of yoga being performed to elicit differences between SBWI+RES and SBWI+VIN.
An interesting finding from this study is that there is a discrepancy between perceived intensity of the styles of yoga depending on how this was assessed. For example, data collected at the end of the intervention indicates that Vinyasa was perceived to be of a higher intensity, with Vinyasa perceived as an intensity more than a brisk walk while the restorative style of yoga was perceived to be similar to the intensity of a brisk walk (Table 4). However, the RPE that was self-reported at the completion of each yoga session did not reflect a significant difference between these styles of yoga. The reason for this difference in perceptual response to effort exerted during different styles of yoga is unclear and may warrant further investigation.
Given that this study was designed as a feasibility study, the perceptual data obtained at the end of the intervention may provide important insights to consider for future implementation of yoga within a SBWI (Table 4). Time was a barrier to yoga participation, particularly as the length of the prescribed yoga sessions increased. This may suggest that yoga sessions that are approximately 60 minutes in duration pose a barrier to participation among adults with overweight or obesity. Durations of yoga sessions ranging between 20 to 40 minutes appear to be preferred over 60 minute sessions. Self-reported data in this study appear to support this, with the mean duration of each yoga session being approximately 30 minutes. Moreover, despite yoga being prescribed to be performed on 5 days per week, the mean frequency of yoga in this study was approximately 2-3 days per week. These findings may suggest the need to further investigate the optimal duration and frequency of yoga that maximizes engagement while also being effective for enhancing health-related outcomes.
This study found that 65.0% of participants in SBWI+RES and 85.0% in SBWI+VIN planned on continuing participation in yoga following the 6-month intervention. This may suggest that Vinyasa yoga is preferred to among adults with overweight or obesity. However, this study also found that retention in SBWI+RES was 92% whereas retention in SBWI+VIN was 80%, which may provide additional insight into the preferred style of yoga among adults with obesity. To our knowledge, there are no other studies that have reported on the comparison of these styles of yoga within the context of a SBWI. Therefore, it is unclear if these findings are unique to this study or whether these would be consistent across other studies with a similar design.
This study is not without limitations that need consideration. This study was designed as a feasibility study, and therefore was not powered to detect potential changes in weight loss or other outcomes between SBWI+RES and SBWI+VIN. Thus, adequately powered studies are needed to fully examine the health benefits of these interventions for adults with obesity. This study was 6 months in duration, and therefore it is unclear if the results reflect what would be observed in a study of longer duration, particularly in understanding the effects on weight loss and weight loss maintenance. This study included measures to understand perceptions of the yoga intervention and measures of health outcomes, but did not include measures of additional pathways by which yoga may impact body weight. This study was also limited to the comparison of two styles of yoga combined within a SBWI. Whether there is a difference between yoga and other forms of physical activity, or yoga combined with other forms of physical activity, on weight loss, fitness, or other outcomes unclear.
This study demonstrated that integrating yoga into a SBWI for adults with overweight or obesity was feasible, and both the SBWI+RES and SBWI+VIN resulted in significant weight loss across the intervention. Findings support that the majority of participants would continue to participate in yoga following the completion of the SBWI. These findings also appear to support the potential inclusion of either SBWI+RES or SBWI+VIN for the treatment of obesity. Whether inclusion of yoga within a SBWI enhances weight loss beyond what is achieved with SBWI combined with other forms of physical activity, such as brisk walking, is unclear.
What is already known about this subject?
Physical activity is an important lifestyle factor for weight loss and weight loss maintenance.
Few studies have examined the feasibility and effect of including yoga within the context of a standard behavioral weight loss intervention.
What are the new findings in your manuscript?
Including yoga was feasible within the context of a standard behavioral weight loss intervention for adults with overweight or obesity.
Vinyasa yoga, compared to a restorative form of Hatha yoga, was more often identified as the style of yoga that was similar in intensity to brisk walking.
Significant weight loss was achieved within the standard behavioral weight loss intervention, with no difference between those prescribed Vinyasa yoga compared to a restorative style of Hatha yoga.
How might your results change the direction of research or the focus of clinical practice?
Inclusion of yoga, as an alternative form of physical activity, is feasible for adults with overweight or obesity and may be included within a standard behavioral weight loss intervention.
Additional research is needed to compare yoga to other forms of physical activity for its long-term effects on weight loss and related health outcomes.
Results need replication in an appropriately powered randomized clinical trial to examine the efficacy and effectiveness of yoga for long-term weight loss and other health benefits among adults with overweight or obesity.
Acknowledgements
We recognize the contribution of the staff and students at the Healthy Lifestyle Institute and the Physical Activity and Weight Management Research Center at the University of Pittsburgh, and the Clinical and Translational Science Institute (CTSI) at the University of Pittsburgh.
Data sharing for this study may be available after publication of the main outcomes, and only made available for requests that meet the approved process contained within the informed consent and other policies at the University of Pittsburgh. These data will not be provided in a public use dataset, but rather may require approval through a material transfer agreement, and only de-identified data will be made available. Investigators interested in data from this study should contact Dr. Jakicic (jjakicic@pitt.edu), who is the principal investigator, for data sharing policies and procedures after publication.
Funding: Support provided by grants R34 AT009361 and UL1 TR001857 from the National Institutes of Health.
Footnotes
Clinical Trial Registration: clinicaltrials.gov NCT03459937
Disclosure: Dr. Jakicic is on the Scientific Advisory Boards for WW International, Inc. and Naturally Slim, and on the Advisory Board for Spark360. Dr. Rogers is a consultant for Naturally Slim. Dr. Sherman is a Lululemon Ambassador.
Contributor Information
John M. Jakicic, Healthy Lifestyle Institute, Physical Activity and Weight Management Research Center, University of Pittsburgh, Pittsburgh, PA USA.
Kelliann K. Davis, Department of Health and Human Development, University of Pittsburgh, Pittsburgh, PA USA.
Renee J. Rogers, Healthy Lifestyle Institute, Physical Activity and Weight Management Research Center, University of Pittsburgh, Pittsburgh, PA USA.
Sally A. Sherman, Department of Health and Human Development, University of Pittsburgh, Pittsburgh, PA USA.
Susan Barr, Healthy Lifestyle Institute, Physical Activity and Weight Management Research Center, University of Pittsburgh, Pittsburgh, PA USA.
Marissa L. Marcin, Healthy Lifestyle Institute, Physical Activity and Weight Management Research Center, University of Pittsburgh, Pittsburgh, PA USA.
Katherine A. Collins, Duke University Medical Center, Duke Molecular Physiology Institute, Durham, NC USA.
Audrey M. Collins, Healthy Lifestyle Institute, Physical Activity and Weight Management Research Center, University of Pittsburgh, Pittsburgh, PA USA.
Nalingna Yuan, Healthy Lifestyle Institute, Physical Activity and Weight Management Research Center, University of Pittsburgh, Pittsburgh, PA USA.
Wei Lang, Center on Aging and Mobility, University Hospital Zurich and University of Zurich, Zurich, Switzerland.
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