Background:
Researchers use mixed meal tolerance tests (MMTTs) to look at how people s bodies respond to eating a meal. However, researchers do not agree on how to decide the number of calories to give in each meal. Some use fixed meals, which are the same size for everyone, and some use adjusted meals, based on the size of the person s body. Researchers want to know which MMTT is best to use for future research.
Objective:
To learn how fixed vs adjusted meals affect blood glucose levels in healthy people.
Eligibility:
Healthy people aged 18 years or older.
Design:
Participants will have 3 or 4 clinic visits of up to 8 hours in 8 weeks.
Participants will have baseline tests:
Their height, weight, and waist size will be measured.
They will have an oral glucose tolerance test: A needle attached to a tube (IV) will be inserted into a vein in the arm. They will have a sugary drink. Blood samples will be taken from the tube at intervals up to 3 hours after the drink.
They will have a body scan.
Participants will have 2 MMTT visits. One will include a fixed meal and one will include an adjusted meal. They will have tests at both visits:
Resting metabolic rate: A clear hood will be placed over the participant s head while they rest for 20 minutes. This will measure the oxygen they breathe in and out.
MMTT. Participants will have 5 minutes to drink a liquid meal. Blood samples will be taken at intervals for the next 4 hours....
Provision of signed and dated informed consent form.
Agreement to adhere to Lifestyle Considerations throughout study duration.
Males and females; Age >= 18years
Healthy, as determined by medical history, physical examination, and laboratory tests.
Current use of medications, dietary supplements, or alternative therapies known to alter energy metabolism.
Fasting plasma glucose >= 126 mg/dL
Type I or Type II Diabetes Mellitus by self-report.
Hematologic disorders including significant anemia (male hemoglobin < 13.0 g/dL or female hemoglobin < 11.0 g/dL)
Crossover
Fixed Mixed Meal Test
Other interventiona FIXED dose meal that will be 900 kcal of a liquid meal
Adjusted Mixed Meal Test
Other interventiona body weight ADJUSTED dose liquid meal. (30% of total daily energy requirements)
To determine whether an adjusted energy dose MMTTor 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.
Glucose AUC associated with MMTT conditions (fixed vs. adjusted).
Body Composition
Change in energy expenditure associated with MMTT conditions (fixed vs. adjusted).
Resting Metabolic Rate
Change in energy expenditure associated with MMTT conditions (fixed vs. adjusted).
Lipids
Change in energy expenditure associated with MMTT conditions (fixed vs. adjusted).
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