Gastric Emptying in Healthy Volunteers and GLP-1 Agonist Users

This observational study aims to determine the gastric emptying kinetics assessed by ultrasound in healthy volunteers after a standard breakfast and the state of the stomach after a clear liquid diet for 18 /24 hours in patients on GLP-1 agonist. The main questions it seeks to answer are:

* Is the kinetic after a standard breakfast that includes ( avocado and eggs: high fat) as fast as a standard meal that does not involve this food? * Is a clear liquid diet of 18 to 24 hours enough to be an empty-stomach, assessed by Ultrasound in patients on GLP1 agonist?

Participants will be asked to do:

-A baseline Gastric US will be performed for healthy volunteers, and then they will have a standardized breakfast. An hourly or bihourly assessment will be done by the US.