Appendix Table 1: Search terms. Unless otherwise stated, search terms are free text terms; exp=exploded MeSH term; tw=textword; pt=publication type; adj=adjacency; dollar sign ($), asterisk (*) and percentage sign (%) =unlimited truncation; question mark (?)=optional wildcard.

Database
Ovid MEDLINE / EMBASE / Cochrane Central Register of Controlled Trials / metaRegister of Controlled Trials
1. Metformin or Glucophage or Riomet or Fortamet or Glumetza or Obimet or Dianben or Diabex or Diaformin
2. exp Metformin/
3. 1 or 2
4. obes$ or obesity
5. Overweight or loss of overweight
6. BMI or Body mass index or Body-mass-index or Weight for height or Weight-for-height or Weight to height ratio or Weight-to-height ratio or Weight height ratio or Weight-height ratio
7. Weight gain or Weight loss or Weight management or Weight maintenance or Weight reduction or Weight decrease or Weight control
8. Waist circumference or Waist measurement
9. Body fat or Body fat percent$ or Percent$ body fat or Fat mass or Adiposity or Body composition
10. Skinfold thickness or skin fold thickness or skin-fold thickness
11. Hyperinsulin?emia or Insulin resistance or metabolic risk or metabolic syndrome
12. Dyslipid?emia or Hyperlipid?emia or Hypercholesterol?emia or Cholesterol or Total cholesterol or Low density lipoprotein cholesterol or LDL cholesterol or High density lipoprotein cholesterol or HDL cholesterol or Triglyceride$
13. Satiety or Hunger or Appetite or Binge eating
14. ponderal index
15. (adverse effect$ or adverse reaction$ or side effect$).tw.
16. exp Obesity/
17. body weight changes/ or overweight/
18. Adipose Tissue/
19. exp "Body Weights and Measures"/
20. exp Hyperinsulinism/
21. exp Dyslipidemias/
22. exp Appetite/
23. or/4-22
24. exp Child/
25. exp Adolescent/
26. juvenile
27. exp Infant/
28. child$
30. infan$
31. teen$
32. P?ediatric$
33. Pediatrics/
34. or/24-33
35. Randomi#ed controlled trial.pt.
36. exp Randomized Controlled Trial/
37. exp Random Allocation/
38. exp Double-Blind Method/
39. exp Single-Blind Method/
40. Clinical trial.pt.
41. exp Clinical Trial/
42. (clinical$ adj5 trial$).tw.
43. (single or double or treble or triple) adj5 (blind$ or mask$)
44. Placebos/
45. (placebo$ or random$).tw.
46. research design/
47. Comparative study/
48. exp evaluation studies/
49. Follow-up studies/
50. Prospective studies/
51. Intention-to-treat.tw.
52. Randomi#ed controlled trial
53. Randomi#ed adj5 controlled
54. or/35-53
55. 34 and 3 and 23 and 54
56. limit 55 to humans / 1. Metformin or Glucophage or Riomet or Fortamet or Glumetza or Obimet or Dianben or Diabex or Diaformin
2. Metformin/
3. 1 or 2
4. obese or obesity or overweight or adiposity or overeating
5. BMI or Body mass index or Body-mass-index or Weight for height or Weight-for-height or Weight to height ratio or Weight-to-height ratio or Weight height ratio or Weight-height ratio
7. Weight gain or Weight loss or Weight management or Weight maintenance or Weight reduction or Weight decrease or Weight control
8. Waist circumference or Waist measurement
9. (Body adj5 fat) or (Body adj5 fat adj5 percent$) or Percent$ body fat or Fat mass or Adiposity or Body composition
10. Skinfold thickness or (skin adj5 fold adj5 thickness) or skin-fold thickness)
11. waist adj5 hip adj5 ratio
12. Hyperinsulin?emia or insulin resistance or metabolic risk
13. Dyslipid?emia or Hyperlipid?emia or Hypercholesterol?emia or Cholesterol or Total cholesterol or Low density lipoprotein cholesterol or LDL cholesterol or High density lipoprotein cholesterol or HDL cholesterol or Triglyceride$
14. Satiety or Hunger or Appetite or (Binge adj5 eat$)
15. appetite/
16. adverse effect$ or adverse reaction$ or side effect$
17. obesity/
18. body mass/
19. body weight/
20. or/4-19
21. Clinical trial/
22. Randomized controlled trial/
23. Randomization/
24. Single blind procedure/
25. Double blind procedure/
26. Crossover procedure/
27. Placebo/
28. Randomi?ed controlled trial$.tw.
29. Rct.tw.
30. Random allocation.tw.
31. Randomly allocated.tw.
32. Allocated randomly.tw.
33. (allocated adj2 random).tw.
34. Single blind$.tw.
35. Double blind$.tw.
36. ((treble or triple) adj blind$).tw.
37. Placebo$.tw.
38. Prospective study/
39. or/21-38
40. child/
41. adolescent/
42. pediatrics/
43. child$
44. adolescen$
45. infan$
46. teen$
47. p?ediatric$
48. juvenile
49. or/40-48
50. 39 and 49 and 3 and 20
51. limit 50 to human / “metformin”,
AND
“child*, adolescen*, teen*”
AND
“obes*, overweight”
in Title, Abstract or Keywords / Metformin
AND
(child% OR adolescen%)
AND
(obes% OR overweight)

Appendix Table 2: Table of excluded studies

Study / Study description / Primary reason for exclusion
Burgert 2008(22) / 4-month randomized double-blind placebo-controlled trial in 28 obese, insulin-resistant adolescents / < 6 months follow-up
Freemark 2007(16) / 6-month randomized double-blind placebo-controlled trial in 29 obese adolescents / Non-unique data set(14)
Kay 2001(23) / 8-week randomized double-blind placebo-controlled trial in 24 hyperinsulinemic obese adolescents / < 6 months follow-up
Klein 2006(24) / 16-week randomized double-blind placebo-controlled trial in 39 subjects aged 10-17 years, whose weight increased by >10% during <1 year of atypical antipsychotic therapy / Participants had weight gain due to antipsychotic therapy
Wiegand 2008(25) / 6-month randomized double-blind placebo-controlled trial in 67 obese children and adolescents (conference abstract) / Insufficient information