All variables were normally distributed. At baseline, the mean age of the participants was 16.52 years (SD = 2.35; range = 11–21) and the mean length of eating disorder illness was 14.3 months (SD = 16.7; range = 0–45 months, with one outlier at 92 months). Over-exercising (daily participation in at least 2 organized sports, plus self initiated exercises, 5–7 days per week) was documented in 48% (n = 24) of the participants prior to the start of the study. According to chart review, 45% of participants (n = 23) had been hospitalized for their eating disorder prior to the start of the study. The majority of the sample was female (n = 46 [92%]), non-Hispanic (n = 47 [94%]), and white (n = 43 [86%]). Twenty nine participants (55%) had Anorexia Nervosa, nine (17%) had Bulimia, and fifteen (28%) had EDNOS.
In addition to study participation, many participants endorsed simultaneous treatment in other therapies and medication usage. Exploratory post-hoc analyses were conducted on participants endorsing the three forms of other treatment with sufficient sample size: Individual psychotherapy (n = 16), art therapy (n = 14), and SSRIs (n = 12). Independent t-tests comparing individuals using each of these treatments with those not using that particular treatment (e.g., those using art therapy vs. those not using art therapy) yielded no significant differences, indicating that none of these treatments had significant effects on outcome measures. Chi square tests of independence confirmed that individuals using these other forms of treatment were equally distributed across the yoga and no yoga groups, thus, there was no confounding of treatment type in the study.
As the FP measure had not been previously validated, correlations between Global EDE scores and the FP measure were examined. FP was significantly positively correlated with Global EDE scores in all but two of 96 instances; both exceptions were positive and marginally significant (ps < .1). These findings provide some evidence for concurrent validity of the measure.
presents the means and standard deviations of the EDE scores for both treatment groups at each assessment point. To test the hypothesis that eating disorder psychopathology would improve over time if the participant received yoga treatment, a 2 (Group- No Yoga vs. Yoga) × 3 (Time- Week 0, 9, 12) mixed model analysis of variance (ANOVA) was performed on participants’ EDE global scores. The results showed support for the hypothesis, with a significant interaction of Group by Time, F(2, 35) = 3.26, p = .05, η2 = .16. Planned comparisons revealed that the two groups’ scores declined between Weeks 0 and 9, but the yoga group’s scores continued to trend downward through follow-up at Week 12, t(21) = 1.74, p =.09. The no yoga group’s scores went in the opposite direction at the follow-up, significantly increasing between Weeks 9 and 12, t(15) = 2.67, p =.02. The overall main effects of Group and Time were non-significant (ps = .59 and .12, respectively). See .
Eating Disorder Examination Scores by Group and Time
Global EDE Scores by Group and Time
The participants’ four EDE subscale scores were then examined individually, to determine what subscales were contributing to the significant interaction of Group and Time in the Global score. A series of 2 (Group) × 3 (Time) mixed model ANOVAs showed no significant effects; the interactions closest to approach significance were for Weight Concern scores, F(2, 35) = 2.79, p = .08, η2 = .14, and Shape Concern scores, F(2, 35) = 2.07, p = .14, η2 = .11. Both of these subscales followed the pattern seen in the Global scores. See for means and standard deviations.
Scores on the BDI and STAI were examined as dependent variables in another series of 2 (Group) × 3 (Time) mixed model ANOVAs. The pattern of results on these measures was highly similar. There were significant main effects of time, such that over the study participants decreased in depression, F(2, 31) = 5.29, p = .01, η2 = .26, state anxiety, F(2, 35) = 4.28, p = .02, η2 = .2, and trait anxiety, F(2, 35) = 10.92, p = < .001, η2 = .38. There were no main effects of group and no significant interactions on these outcome measures (all ps > .3); essentially, participants improved over time in both groups. See for descriptive statistics.
Depression, Anxiety, and BMI scores by Group and Time
For BMI, data were analyzed by group and time and also by diagnosis in a 2 (Group) × 3 (Time) × 3 (Diagnosis) mixed model ANOVA, as treatment goals for weight outcomes differ by diagnosis. Both the no yoga and yoga groups improved over time, but not significantly so, F(2,62) = 1.28, p = .28. There was a significant main effect of group, such that the yoga group had somewhat higher overall BMI at all time points than the no yoga group, F(1,31) = 4.83, p = .04, η2 = .14. There was a significant main effect of diagnosis, such that the BN and EDNOS participants had significantly higher BMIs than the AN group at all time points, F(1,31) = 9.90, p < .001, η2 = .39. There were no other significant main effects or interactions, indicating that the yoga treatment did not adversely affect BMI over time. This was true for all three diagnostic categories. See for the yoga group’s data, and for descriptive statistics on BMI in both groups. BMI increased or stayed the same in 62.2% of the sample at the 12 week followup. In the remainder of the sample, only 17.7% had BMI losses of greater than .5 points.
BMI of Yoga Group by Diagnosis and Time
Participants were assessed on food preoccupation before and after each of 16 yoga sessions. For this analysis, data for the yoga group and the no yoga group (who completed yoga after the study was over) were combined. Participants in both groups completed the same measures before and after yoga sessions and there were no significant differences between groups in any of the session means to indicate they should be considered separately. Paired t-tests revealed highly significant differences (ps < .01) from pre-test to post-test in all 16 sessions, such that participants indicated less food preoccupation after doing yoga. Seven sessions had pre-post differences in the medium effect size range according to Cohen’s criteria (.4 < d < .8), and the other nine sessions had large effect sizes (d > .8).