Introduction: Obesity poses a significant increase in morbidity and mortality 
and thus five anti-obesity drugs have been approved currently by US FDA. Several 
phase 3 trials have shown a significant improvement in cardio-metabolic profile 
including significant weight reduction with these agents compared to 
placebo.Areas covered: We systematically searched the database of PubMed, 
Embase, The Cochrane Library and The ClinicalTrials.gov up to 30 September 2019 
and retrieved all the randomized controlled trials (RCTs) that were conducted 
with these five drugs for ≥1 year and explicitly reported their efficacy versus 
placebo. Subsequently, we have conducted the meta-analysis to primarily study 
the effect of these anti-obesity drugs on weight reduction. We additionally 
reviewed the effect of these drugs on other cardio-metabolic parameters 
including key adverse events.Expert opinion: This meta-analysis finds a 
significant reduction in body weight with orlistat (N = 10,435; ∆ -3.07 Kg, 95% 
CI, -3.76 to -2.37), phentermine plus topiramate (N = 2985; ∆ -9.77 Kg; 95% CI, 
-11.73 to -7.81), lorcaserin (N = 16,856; ∆ -3.08 Kg; 95% CI, -3.49 to -2.66), 
naltrexone plus bupropion (N = 3239; ∆ -4.39 Kg; 95% CI, -5.05 to -3.72) and 
liraglutide (N = 4978; ∆ -5.25 Kg; 95% CI, -6.17 to -4.32), compared to placebo 
(all p < 0.00001).