Mechanisms Underlying Individual Variations of Taste and Smell in Obesity

Background: Changes to the sense of taste or smell can change eating behavior. This may contribute to obesity. Researchers want to see how taste and smell perceptions that affect food choices may differ between people with obesity and without obesity. Objective: To understand the role that senses of taste and smell play in food intake. Eligibility: Adults ages 18-65 with obesity and without obesity Design: Participants will be screened with a medical history and physical exam. They will have a neurological and sensory exam. They will give blood and urine samples. They will be checked for previous SARS-CoV-2 infection. They will complete questionnaires about their eating habits, alcohol use, and smoking history. Participants will have 2 study visits. Participants will give stool, urine, blood, hair, nasal, and saliva samples. These samples will be used for gene testing. Participants will have their weight, height, and hip and waist circumference measured. They will have an imaging scan that measures body composition. Participants will complete questionnaires about their health, eating habits, and food preferences. Participants will have taste tests and smell tests. They will have sensory tests to assess their response to stimuli. Participants will have a dietary assessment. They will complete a food diary and a diet history questionnaire. Participants will get a meal to eat. Data will be collected about their experience. Participants will complete a sleep diary and wear a watch to measure their activity....

* INCLUSION CRITERIA: In order to be eligible to participate in this study, an individual must meet all of the following criteria: * Males and females between 18 to 65 years of age. Due to documented knowledge that taste and smell changes with age, we will limit the cohort within this age range. * BMI between 18.5 and 29.9 kg/m\^2 for healthy controls or between 30 and 39.9 kg/m\^2 for obese subjects at screening * Fasted plasma glucose levels between 68-126 mg/dl or per Clinical Center ranges, and hemoglobin A1C\ 10 K/uL, Red Blood Cell Count \< 4 or \> 7 M/uL, Hemoglobin \< 12 g/dL for females or \< 13 g/dL for males or any clinical signs/symptoms that indicate iron deficiency anemia per clinician's judgment at screening \[National Heart, Lung and Blood Institute (NHLBI) definition (Anemia - Iron-Deficiency Anemia, Diagnosis; NHLBI, NIH)\]. * Bariatric surgery within the last 12 months of screening. * History of cancer (e.g., head and neck cancer) and/or history of cancer treatment (e.g., radiotherapy to the head and neck area or chemotherapy). * Altered cranial nerves identified by neurological evaluation during physical exam (screening visit). * Currently experiencing temporary change/loss of taste and/or smell. * Persistent loss of taste and/or smell due to COVID-19 or other reasons. * Unable to read and understand English. Since all self-report measures are in English only, participants need to be able to read and understand the English language. * NIAAA employees/staff or subordinates/relatives/co-workers of NIAAA employees/staff or study investigators.