Discovering Determinants of Food Intake by Application of Artificial Intelligence to Complex, High-Dimensional Data

Background: Many people in the United States are overweight or obese. Researchers want to learn why some people can overeat and not gain weight, whereas others who do not overeat still gain weight. Objective: To study factors related to food intake that can lead to weight gain over time. Eligibility: Healthy adults aged 18 to 60 years. Design: Participants will have 6 to 8 clinic visits over 2 years. The first 3 or 4 study visits will be 1 week apart. Procedures during visits may include the following: Collection of blood, hair, urine, and stool samples. Measurement of the waist, neck, thighs, and other parts of the body. Dual energy x-ray absorption (DXA) scan: Participants will lie still on a padded table while they are scanned to measure body fat. Physical activity monitor: Participants will wear a monitor on the wrist for 2 weeks. Cognitive tests: Participants will perform tasks to measure attention, memory, and brain function. Continuous glucose monitor. Participants will wear a device that measures their blood glucose for 1 week. Mixed meal test and stomach emptying test. Participants will drink a breakfast shake and swallow a dose of acetaminophen. Blood will be drawn over the next 4 hours. Resting metabolic rate: Participants will wear a clear hood over their head while they rest for 20 minutes. The hood will measure the gases they breathe. Breakfast and lunch test. Participants will eat a standard breakfast. They will be allowed to select from foods and eat as much as they like at lunch. They will be asked how hungry or full they are. Questionnaires. Participants will answer questions about their health, sleep, physical activity, and eating.

* INCLUSION CRITERIA: To be eligible to participate in this study, an individual must meet all the following criteria: 1. Stated willingness to comply with all study procedures and availability for the duration of the study 2. Age 18 to 60 3. In good general health as evidenced by medical history and physical exam EXCLUSION CRITERIA: An individual who meets any of the following criteria will be excluded from participation in this study: 1. Weight \>=204 kg (\>=450 pounds, maximum weight of the iDXA machine as per manufacturer s manual), or weight \= 6.5%, or history 6ii. Surgery for treatment of obesity 6iii. Endocrine disorders, such as Cushing s disease, pituitary disorders, or hypo- and hyperthyroidism (TSH \= 10 uIU/mL) 6iv. Pulmonary disorders including chronic obstructive pulmonary disease or other lung disease that which would limit ability to follow the protocol 6v. History of coronary artery disease, heart failure, arrhythmias, and peripheral artery disease that which would limit ability to follow the protocol 6vi. Liver disease, including cirrhosis, active hepatitis B or C based on history, and AST or ALT \>= 3x normal 6vii. Gastrointestinal disease including Crohn's disease, ulcerative colitis, celiac disease, or other malabsorptive disorders by history 6viii. Hematologic disorders including significant anemia (male hemoglobin \< 13.0 g/dL or female hemoglobin \< 11.0 g/dL) 6ix. Renal disease including abnormal kidney function (eGFR \= 2 skipped cycles and an interval of amenorrhea \>= 60 days and \= 8-point score on the Alcohol Use Disorders Identification Test (AUDIT) questionnaire interview 8\. Inability to provide informed consent 9\. Any disorder, unwillingness, or inability not specifically mentioned above may serve as criteria for exclusion at the discretion of the investigators, such as those that jeopardize the safety of the participant or others, or would interfere with completion of study procedures