Appropriate study power will be achieved with 35 participants in the weight loss group and 35 participants in the weight maintenance control group (see Data Analysis and Statistical Considerations). We will recruit and enroll obese (BMI ≥29 - ≤40) men and women, age 18 to 45, with no previous history of lower extremity injury, no evidence of symptoms OA, no knee misalignment (neutral alignment between 178° and 182°), or other injury that would prevent them from performing the walking task required by this study. All inclusion criteria specific to knee injury, OA, and alignment will be verified by MRI scan. All participants in this study will be informed of the risks involved. Upon expressing interest in study participation, participants will be asked questions to determine whether they are free of lower extremity injury and their height and weight will also be recorded to determine their BMI. Potential participants will be pre-screened by phone using a phone script with a list of questions. Once it is determined they meet all study inclusion criteria, they will be invited to attend a consent meeting.
