Inclusion Criteria:

• BMI 18-25 kg/m^2.
• Age > 21 and < 50 years.
• Weight stable for 3 months prior to study entry.
• For females: study days will be scheduled during the follicular phase of their menstrual cycle (i.e., the first 13 days (about 2 weeks) of the cycle).
• Able to provide written informed consent prior to any study procedures and be willing and able to follow study procedures.
• Ability to perform light to moderate physical activity.

Exclusion Criteria:

• Any contraindication for MRI scanning.
• Any history of childhood (> 95th percentile) or adult obesity (BMI >30 kg/m^2).
• Claustrophobia.
• High intensity training or physical activity.
• Any contraindication for intragastric balloon insertion.
• Any allergies to the study meals.
• Any history of eating disorder.
• Any substance abuse disorder (including alcohol and tobacco).
• Any history of psychiatric disorders.
• Any cardiovascular, endocrine, pulmonary, neurological, or gastrointestinal comorbidities.
• Pregnancy or nursing.
• Any history of bariatric surgery or endoscopic bariatric procedure.
• Use of any medication or supplement that alters appetite.
• Patient has a known history of any condition or factor judged by the investigator to prevent participation in the study or which might hinder study adherence.

Eligibility last updated 10/6/21. Questions regarding updates should be directed to the study team contact.