Variability In Mixed Meal Tests: Fixed Versus Adjusted to Energy Needs Caloric Dose

Study Description: This study will be an outpatient study completed in 3-4 separate visits. We will compare two methods of dosing (fixed and adjusted) a mixed meal tolerance test (MMTT) to determine which results in greater physiological variability in hormone response. Ultimately, the goal is to determine which method of dosing is more appropriate in a research setting. Objectives: Primary Objective: To determine whether an adjusted energy dose MMTT or a fixed dosed meal will result in greater variability in glucose area under the curve (AUC) within the same participants across a range of BMIs. Secondary Objectives: To determine whether baseline body composition, blood parameters (lipids, hormones, etc), and resting metabolic rate are associated with MMTT responses and whether this association is moderated by MMTT condition (fixed vs. adjusted). Endpoints: Primary Endpoint: Glucose area under the curve (AUC) Secondary Endpoints: Area under the curve (AUC), incremental area under the curve (iAUC), value and timing of the absolute maximum (peak), value and timing of the inflection point after the absolute maximum value, value and timing of the maximum rate of incline, value and timing of the maximum rate of decline, total number of critical points with body composition, blood parameters, and resting metabolic rate as predictors.