Obesity affects over one third of US adults (\>72 million, with BMI ≥30 kg/m2), and the proportion of US adults with BMI ≥40 kg/m2 has doubled in the last 20 years. Obesity is associated with increased mortality through its linkage to comorbidities including diabetes, hypertension, dyslipidemia, osteoarthritis, sleep apnea and psychosocial disturbances. Given its prevalence, impact on morbidity and mortality, and economic cost, limiting the spread of obesity and its consequences is one of the most important problems of our time. In this proposed study, investigators will recruit participants from a wide range of body mass index (BMI), ethnicity and Diabetes risk to collect data and blood, stool and adipose tissue samples in the San Francisco bay area.