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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.

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.

Inclusion Criteria:

Inclusion Criteria:

• Obese (BMI percentile ≥95th for age and gender)
• Hispanic males and females who are 12-18 years of age and are ≥Tanner Stage 4.

Exclusion Criteria:

Participants will be excluded from the study if any of the following apply:

1. diagnosis of any disease that is known to influence insulin action and secretion (including type 1 and 2 diabetes);
2. current or past involvement in any weight loss, exercise, or sports program in the six months prior to participation
3. use of medication known to influence body composition or fat distribution (e.g. Cushing syndrome), insulin resistance, gut function, or lipid profiles;
4. history of renal / liver disease or any disease affecting liver fibrosis and steatosis;
5. diagnosis/current treatment for celiac, inflammatory bowel disease, Crohn's disease or other major GI issues;
6. those who are immune compromised;
7. pregnancy;
8. current smoking (more than 1 cigarette in the past week), >200 cigarettes in lifetime, or use of other recreational drugs;
9. alcohol consumption;
10. other siblings in the study;
11. physician diagnosis of major illness or eating disorder;
12. physical/cognitive handicaps preventing participation;
13. and recent antibiotic treatment (within the previous 30 days).