Network meta- analysis revealed that in adolescents , intervention with 2000 mg/day metformin ranked better than other interventions ; however , 1000 mg/day metformin for 3 months may be most suitable for adolescents .
For adults , metformin at doses of 3000 and 1000 mg/day ranked the highest , other than minimeal and lifestyle interventions ; moreover , intervention with 3000 mg/day for 6 months and 1000 mg/day for 0.5 months may be suitable for adults .
Conclusion When considering the efficacy of interventions for losing weight , metformin offers clear advantages for overweight and obese population
Purpose Our aim was to assess the efficacy of metformin for weight loss in overweight and obese people through a systematic review and network meta- analysis and to identify the most suitable dosage and intervention period for using metformin  in adolescents and adults .
Beneficial effects of metformin in normoglycemic morbidly obese adolescents.
Hyperinsulinemia and insulin resistance are common features of obesity in humans and experimental animals . It has been demonstrated that metformin , an antihyperglycemic agent , decreases hyperinsulinemia and insulin resistance leading to decreased adiposity in obese and non-insulin-dependent diabetes mellitus ( NIDDM ) adults . To evaluate the antiobesity effect of metformin , we conducted a r and omized double-blind placebo controlled trial in 24 hyperinsulinemic nondiabetic obese adolescents ( body mass index [ BMI ] > 30 kg/m(2 ) ) . All subjects were placed on a low-calorie ( 1,500 kcal for women and 1,800 kcal for men ) meal plan . After an initial 1-week lead-in period , 12 subjects ( mean + /- SE for age and BMI , 15.6 + /- 0.4 and 41.2 + /- 1.8 , respectively ) received metformin ( 850 mg twice daily ) for 8 weeks , and 12 subjects ( mean + /- SE for age and BMI , 15.7 + /- 0.5 and 40.8 + /- 1.4 , respectively ) received placebo . Compared to the placebo group , the metformin group had greater weight loss ( 6.5 % + /- 0.8 % v 3.8 + /- 0.4 % , P < .01 ) , greater decrease in body fat ( P < .001 ) , greater increase in fat-free mass to body fat ratio ( P < .005 ) , and greater attenuation of area under the curve ( AUC ) insulin response to an oral glucose tolerance test ( P < .001 ) . This was associated with enhanced insulin sensitivity , as determined by the fasting plasma glucose : insulin , 2-hour glucose : insulin , and AUC glucose : AUC insulin ratios , in the metformin group compared to controls ( P < .01 ) . This corresponded to a significant reduction in plasma leptin ( P < .005 ) , cholesterol , triglycerides , and free fatty acid ( FFA ) levels ( P < .05 ) only in the metformin-treated subjects . Combined metformin treatment and low-calorie diet had a significant antiobesity effect in hyperinsulinemic obese adolescents compared to a low-calorie diet alone
Network meta- analysis revealed that in adolescents , intervention with 2000 mg/day metformin ranked better than other interventions ; however , 1000 mg/day metformin for 3 months may be most suitable for adolescents .
For adults , metformin at doses of 3000 and 1000 mg/day ranked the highest , other than minimeal and lifestyle interventions ; moreover , intervention with 3000 mg/day for 6 months and 1000 mg/day for 0.5 months may be suitable for adults .
Conclusion When considering the efficacy of interventions for losing weight , metformin offers clear advantages for overweight and obese population
Purpose Our aim was to assess the efficacy of metformin for weight loss in overweight and obese people through a systematic review and network meta- analysis and to identify the most suitable dosage and intervention period for using metformin  in adolescents and adults .