Volunteers planned to undergo RYGB will be studied during two-9 days periods of identical and controlled diet and activity, separated by a 4-10-week washout period.
Study Period #1:
This first study period is 9 days/nights long and requires you to be closely supervised at our Clinical and Translational Research Center (CTRC). During this time you will receive the same diet and are expected to have the same activity level you will be prescribed in the immediate post-operative period.
Wash-out period:
During this study period you are expected to return to your usual diet and exercise level.
Study Period #2:
This last study period is also 9 days/nights long, includes the EXACT same diet you have received during the first study period, and in addition you will undergo the planned gastric by-pass surgery.
Procedures during the research:
Mixed Meal Challenge test will be done four times during the entire study: days 1 and 9 for each study period. This test allows the investigators to evaluate how much insulin your body is producing and how well this insulin is processed.
Measurement of resting energy expenditure will be done four times during the entire study. This test tell us how much energy your body is burning up in a resting state.
