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<6.5%
- Able to provide his/her own consent
- Able to understand the protocol, as shown by scoring a 6 out of 6 on a consent quiz
EXCLUSION CRITERIA:
An individual who meets any of the following criteria will be excluded from participation in this study:
- Because type-2 diabetic subjects have blunted taste responses, subjects with diagnosis of type II diabetes will be excluded.
- Hypoglycemic drug intake.
- Weight change of more than 15 pounds in the 6 months prior to screening
- Positive pregnancy test, currently pregnant or breastfeeding.
- Currently using any of the following medications: steroidal or nonsteroidal antiinflammatory medications, medications known to inhibit taste response (GLP1 agonists), antiepileptic or antidepressant agents, glucocorticoids, or antibiotics.
- Received a diagnosis by a medical professional of morbid obesity, liver or renal disease.
- Individuals with current heavy drinking. Women who drink 4 drinks or more in one occasion and 7 drinks in a week. Men who drink 5 drinks or more in one occasion and more than 14 drinks a week.
- Use of tobacco products or illicit drugs (as determined by urine drug screen and/or history/physical exam) in the last 30 days.
- Currently have an uncontrolled medical disorder (i.e., gastrointestinal, endocrine, cardiac, psychiatric).
- Any self-reported history of chronic rhinitis, eating disorder (including binge eating), chronic upper respiratory infection, chronic allergic rhinitis, or nasal polyps in the last 6 months of screening, or current daily use of nasal sprays.
- Abnormal complete blood count (CBC): White Blood Cell Count < 4 or > 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.