In this study, there is 1 year of active subject participation and long-term follow-up data collected at year 5. Since study objectives were met with active subject data, the study team will not be collecting long-term data at year 5.

This study evaluates if measuring resting metabolic rate (the number of calories the body burns at rest) before surgery can help predict successful weight loss after surgery.

This is a prospective study enrolling patients from the Baylor Weight Loss Surgery Center who have met all of the requirements to proceed with primary bariatric surgery. Patients will undergo pre-operative and post-operative metabolic testing (6 months, and 1 year after surgery) using a portable calorimeter with eventual follow up of medical record at 5 years. Data from up to 50 patients will be collected. The main objectives are to examine if the pre-operative resting metabolic rate can accurately predict successful weight loss after bariatric surgery and if it can be used to guide the selection of the type of bariatric surgery that would be most successful for the patient.

Inclusion Criteria:

• All patients scheduled for a primary bariatric surgery
• 18 years of age to no upper limit