Inclusion Criteria:

• Age 18-65 years old.
• Willing to provide consent.
• Gender:  men or women.
• BMI: 18.5-25 healthy subjects, or ≥ 30 with or without “hungry gut” phenotype.

Exclusion Criteria:

• Individuals who are unable to sign consent (e.g., mentally challenged, those declared legally incompetent).
• History of abdominal GI surgery other than appendectomy.
• Bleeding disorder.
• Positive history of chronic gastrointestinal diseases, or systemic disease that could affect gastrointestinal motility, or use of medications that may alter gastrointestinal motility, appetite or absorption, e.g., orlistat, phentermine.

Any acute or chronic condition or other disease that, in the opinion of the Investigator, would limit the subject’s ability to complete and/or participate in this clinical study.  Participant activities:

• If recruited for the investigation participants will be asked to refrain from donating blood;
• Refrain from participating in other research studies;
•  Avoid taking any additional over the counter or prescription medications or herbal supplements that have not been reviewed and approved by the physician or the study coordinator until the study has been completed.