This study will recruit 40 obese Hispanic youth (12 - 18 years of age who are greater than or equal to Tanner stage 4) from hospitals, clinics, and community centers. Participants will be randomly assigned to 16 weeks of probiotics (3 packets/day of VSL#3) or matched placebo. The purpose of this study is to demonstrate through a proof-of-concept trial that probiotics have the potential to alter the gut microbiome and gut hormones.