Table 1 Basic characteristics of the included studies (n = 22)

01

Misra, M, 2020 [27]

Cohort study

7

SG

Over 12 months

24, F/M

17.80 ± 0.40

①②④

N

–

24, F/M

17.10 ± 0.50

02

Miriam A, 2020 [28]

Prospective study

8

SG

At 12 months

26, F/M

18.00 ± 2.10

③^b⑥

N

–

26, F/M

17.00 ± 2.30

03

Madhusmita M, 2020 [26]

Cohort study

6

SG

Over 12 months

22, F/M

18.30 ± 2.35

①②③⑤

N

–

21, F/M

17.00 ± 2.35

04

Laurel L, 2019 [29]

Prospective study

8

RYGB

At 12 months

24, F/M

49.60 ± 1.40

③

DSE

–

27, F/M

47.40 ± 1.50

05

Masayuki Iki, 2019 [30]

Cohort study

8

G

52.8 ± 13.2 (months)

132, M

74.6 ± 5.5

③

N

51.6 ± 12 (months)

1853, M

72.9 ± 5.2

06

M R. Crawford, 2017 [31]

RCT

N

RYGB

At 12 months

10, F/M

50 ± 7

④^a

12–80.4 ± 15.6 months

At 80.4 ± 15.6 months

SG

At 12 months

2, F/M

12–80.4 ± 15.6 months

At 80.4 ± 15.6 months

IMT

At 12 months

4, F/M

12–80.4 ± 15.6 months

At 80.4 ± 15.6 months

07

A H. Maghrabi, 2015 [33]

RCT

N

RYGB

At 12 months

18, F/M

48 ± 4

④^a

At 24 months

SG

At 12 months

19, F/M

At 24 months

IMT

At 12 months

17, F/M

At 24 months

08

Menegati, G C, 2015 [32]

Cohort study

7

RYGB

6–64 months

25, M

38.90 ± 7.39

①③

DSE

–

33, M

38.90 ± 7.39

09

T. L. Costa, 2014 [35]

Cohort study

7

BS

33.3 ± 15.8 months

56, F/M

36.4 ± 8.5

①③

N

–

27, F/M

36.9 ± 9.6

10

Renata, 2010 [37]

Cohort study

7

BS

–

15, M

35.07 ± 7.36

①③

N

–

14, M

34.71 ± 8.09

11

Juan P, 2009 [38]

Cohort study

6

RYGB

12–60 months

26, M

58.00 ± 3.90

①③

N

–

26, M

57.50 ± 4.70

12

Gómez, J. M, 2019 [39]

Cohort study

7

RYGB

Over 12 months

41, M

46 ± 9.2

⑤

N

–

25, M

48 ± 7.6

13

de la Maza, M. P, 2008 [40]

Cohort study

7

RYGB

over 18 months

33, M

44.42 ± 8.87

①③

N

–

29, M

41.76 ± 8.87

14

Pereira, F. A, 2007 [41]

Cohort study

8

RYGB

9.8 ± 1.9 months

16, M

37.80 ± 6.80

①③⑥

N

–

11, M

37.20 ± 10.25

N

–

12, M

32.40 ± 0.03

15

Goode, L. R, 2004 [42]

Cohort study

8

RYGB

48 ± 12 months

23, M

41.00 ± 5.00

①③

RYGB

48 ± 12 months

21, M

54.00 ± 7.00

N

–

23, M

43.00 ± 6.00

N

–

21 + 21, M

55.00 ± 7.00

16

Coates, P. S, 2004 [43]

Cohort study

8

LRGB

10.8 ± 2.6 months

25, F/M

51.00 ± 8.00

⑥

N

–

30, F/M

49.00 ± 10.00

17

Guney, 2003 [44]

Cohort study

8

VBG

At 12 months

16, F/M

34.18 ± 7.72

①②③

N

–

65, F/M

42.00 ± 5.42

18, F/M

58.2 ± 18.2 (F)

①③

18

Heiskanen, J. T, 2001 [45]

Retrospective study

7

G

71 ± 20 months

61.6 ± 10.1 (M)

46, F/M

57.5 ± 14.0 (F)

N

–

59.4 ± 4.6 (M)

19

Inoue, K, 1992 [47]

Retrospective study

7

G

24–60 months

34, M

50–69

③

G

72–120 months

11, M

N

–

115, M

20

Hintze, L. J, 2014 [34]

Retrospective study

7

BS

≤ 16 months

20, M

36.85 ± 26.5

①③⑤

17–36 months

12, M

45.8 ± 10.18

over 37 months

8, M

51.75 ± 12.15

N

–

21, M

43.40 ± 15.70

21

Yu, E. W, 2013 [36]

Prospective study

8

BS

At 12 months

30, F/M

47 ± 14

②^a④^a

N

–

19, F/M

46 ± 16

22

Ott, M. T, 1992 [46]

Retrospective study

7

RYGB

120 months

26, F

45

①

N

–

7, F

46