Participants in the early group are individuals that have established agreements with their clinical providers to begin treatment with semaglutide or tirzepatide as part of their ongoing weight management strategy.

These participants will complete a meal challenge before they start the medication and 6 weeks after starting medication.

Participants in the late group are individuals that have lost >12% of their body weight on either semaglutide or tirzepatide and are still taking the medication.

These participants will complete a meal challenge before they discontinue medication and 3 weeks after discontinuing the medication.

The meal challenge scheduled for 4-6 days after the patient's last injection. The study team will insert an indwelling venous catheter into the participant's forearm for serial blood draws. Immediately prior to the meal, participants will consume 1500 mg of acetaminophen (off-label) to facilitate the analysis of gastric emptying. The participant will then begin the meal challenge by eating the test meal, a breakfast casserole, containing 33% of their current resting energy expenditure needs estimated by Mifflin-ST Jeor equation with a composition of 50% carbohydrate, 30% fat and 20% protein. Participants must completely consume the test meal within 25 minutes of initiating the meal. Participants will fill out behavioral questionnaires after consuming the test meal. After the 2-hour blood draw period, participants will be dismissed. Blood will be drawn prior to the meal and at 5, 10, 15, 30, 60, 90, and 120 minutes after initiating the meal.

Number of participants recruited for the study.

Number or participants able to tolerate and complete the test meal.

Percentage of participants enrolled that complete the protocol