Abstract Obesity treatment can produce variable outcomes for different individuals. The aim of this analysis in adolescents with obesity was to investigate if baseline participant characteristics associated with BMI reduction from baseline to 56 weeks when treated with mid- or top-dose phentermine/topiramate (PHEN/TPM) compared to placebo. A secondary analysis of a randomized, double-blind, placebo-controlled, clinical trial evaluating PHEN/TPM in adolescents with obesity was conducted.