This is a short term study of the effects of bariatric surgery on body composition, gait parameters during walking, lower extremity joint pain and quality of life (QOL) in morbidly obese patients who are already scheduled for a bariatric surgical procedure.

This is a prospective, exploratory, short term study of the effects of bariatric surgery on body composition, gait parameters during walking, lower extremity joint pain and quality of life (QOL) in morbidly obese patients. All patients who enroll have already agreed to undergo the bariatric procedure with their respective surgeon; the study team will simply follow specific outcome measures in addition to their normal clinical care at two time points after the surgery (week 4 and month 3).

Inclusion Criteria:

• no urgent need for bariatric procedure
• 21-65 years of age
• body mass index (BMI) 35 kg/m2 or greater, defined as morbid obesity
• waist circumference of < 66 inches
• able to walk independently

Exclusion Criteria:

• < 21 or > 65 years of age
• pregnancy; psychiatric conditions; binge eating patterns; Prader-Willi syndrome; drug dependency; dementia or other neurodegenerative diseases that would preclude appropriate cognitive or physical ability to perform study protocol
• uncontrolled diabetes (not using meds)
• waist circumference of > 66 inches
• orthopedic conditions that prevent ambulation (severe painful osteoarthritis of the hip or knee)
• patient is wheelchair bound

All subjects will be patients already scheduled to undergo bariatric surgery for weight loss.