Table 1 Comparisons of variables of interest at T1 and T2

TAS

58.4 (12.5), 29–81

51.9 (13.3), 24–76

t(36) = 4.3, p < .001, [3.4 9.6]*

d = 0.70

DIF

22.6 (6.7), 7–34

18.9 (7.3), 7–32

t(36) = 4.8, p < .001, [2.1 5.2]*

d = 0.79

DDF

16.1 (5.0), 5–25

14.2 (4.4), 6–24

t(36) = 3.2, p = 0.002, [0.6 3.0]*

d = 0.52

EOT

19.8 (4.1), 12–27

18.7 (4.8), 9–27

t(36) = 1.9, p = 0.035, [− 0.1 2.1]

d = 0.31

DERS

53.6 (15.2), 22–82

46.5 (15.7), 20–78

t(36) = 3.6, p < .001, [3.1 11.0]*

d = 0.59

Strategies

9.6 (3.5), 3–15

8.5 (4.0), 3–15

t(36) = 2.6, p = 0.006, [0.3 2.1]

d = 0.43

Non-acceptance

9.8 (3.5), 3–15

8.3 (3.4), 3–15

t(36) = 3.5, p < .001, [0.7 2.5]*

d = 0.58

Impulse

7.6 (3.6), 3–15

6.4 (3.3), 3–14

t(36) = 2.9, p = 0.003, [0.4 2.1]

d = 0.48

Goals

11.2 (3.4), 3–15

9.8 (3.3), 3–15

t(36) = 2.6, p = 0.007, [0.3 2.6]

d = 0.43

Awareness

7.1 (2.6), 3–13

6.7 (2.6), 3–13

t(36) = 1.0, p = 0.162, [− 0.4 1.1]

d = 0.16

Clarity

8.1 (3.0), 3–15

6.9 (2.7), 3–12

t(36) = 3.2, p = 0.002, [0.4 2.0]*

d = 0.52

EBQ

23.3 (5.9), 12–38

20.6 (7.2), 9–39

t(36) = 3.6, p < .001, [1.1 4.2]*

d = 0.59

Controllability

25.9 (7.7), 8–40

21.4 (8.4), 8–42

t(36) = 4.3, p < .001, [2.4 6.6]*

d = 0.71

Usefulness

20.6 (5.9), 9–36

19.8 (8.2), 8–44

t(36) = 1.08, p = 0.153, [− 0.8 2.4]

d = 0.17

PHQ-9

12.8 (7.2), 0–27

9.4 (7.0), 0–27

t(36) = 4.2, p < .001, [1.7 5.0]*

d = 0.69

GAD-7

10.8 (6.1), 0–21

6.9 (5.1), 0–21

t(36) = 5.8, p < .001, [2.5 5.2]*

d = 0.95

ED-15

3.6 (1.3), 0–6

2.7 (1.4), 0–6

t(36) = 5.3, p < .001, [0.6 1.3]*

d = 0.87

Weight concern

3.7 (1.6), 0–6

2.7 (1.6), 0–6

t(36) = 5.21, p < .001, [0.6 1.5]*

d = 0.86

Eating concern

3.5 (1.2), 0–6

2.8 (1.3), 0–6

t(36) = 4.3, p < .001, [0.4 1.1]*

d = 0.70

Bingeing

2.5 (2.7) 0–10

2.0 (2.9) 0–14

z = − 2.1, p = 0.033

r = − 0.35

Vomiting

1.4 (4.0) 0–20

1.1 (3.6) 0–5

z = − 1.3, p = 0.190

r = − 0.21

Laxative

0.5 (1.4) 0–7

0.4 (1.1) 0–7

z = − 1.4, p = 0.157

r = − 0.23

Dieting

3.3 (2.5) 0–7

2.5 (2.3) 0–7

z = − 2.0, p = 0.049

r = − 0.33

Exercise

2.0 (2.1) 0–14

1.7 (1.8) 0–6

z = − 1.1, p = 0.275

r = − 0.18