Additional Study Information: We are seeking adult volunteers with body mass index in the obesity range (30-45 kg/m2) to come in for a single study visit where they answer some health questions and have a small volume of blood drawn (25 cc/1.7 tbsp). We will measure levels of the blood sugar-lowering hormone insulin as well as glucose (sugar), certain fats, and other molecules related to metabolism. Participants may be invited to enroll in other studies we are conducting of the role of high insulin levels in liver fat production, but participating in this study does not create any obligation to join those other studies. Participants will be compensated $50 plus reimbursement of round-trip bus or subway fare (where applicable).