Recent studies suggest that probiotic supplementation has the potential to restore gut microbiota homeostasis and reduce fatty liver. No studies have examined the effects of probiotic supplementation on the gut microbiome in obese Hispanic youth who are increased risk of type 2 diabetes and fatty liver. Therefore, the investigator proposes a double-blind randomized trial of probiotic supplementation in obese Hispanic youth in order to determine if probiotic supplementation results in alterations to the gut micro biome. 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. As a secondary aim the investigator will examine wether any changes in the gut microbiome are related to changes in liver fat, fibrosis, glycemia, or body weight. The study team 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. The studies primary outcome is alterations in the composition of the gut microbiome which will be examined through fecal and blood bacterial profiling (16S DNA targeted metagenomics), markers of gut permeability/bacterial translocation, and gut derived hormones involved with appetite regulation (GLP-1, peptide YY, ghrelin). Secondary outcomes include liver fat and liver fibrosis (MR elastography), total body fat (DEXA), visceral fat (MRI). Participants will be randomly assigned to 16 weeks of probiotics (3 packets/day of VSL#3) or matched placebo. The main effects of the intervention will be evaluated in a general linear model, with change in outcomes as the dependent variable and active intervention group as the independent variable. Covariates will include sex, BMI percentile, the baseline value of the outcome variable, as well as baseline factors found to differ among groups. Post hoc pairwise comparisons of the two groups will adjust for multiple comparisons using a Tukey correction.