Literature suggests that obesity affects gait by possibly affecting muscles responsible for locomotion and thus altering the patterns of muscular loading and unloading. 30 teenagers (13-19 yo) were recruited from local schools and weight loss programs; 10 of them had normal BMI, 10 were overweight, and 10 were obese. They first walked at the slow pace and then ran at a faster pace on a treadmill with two force plates embedded under the belt. Various spatial, temporal, and force parameters were measured for each trial. The study found that weight acceptance peak force and push-off peak force, when normalized by body weight, was significantly lower in obese teenagers. In addition, stance time was increased, and step length was decreased in obese teenagers. These changes suggest that muscular loading and unloading in obese teenagers is, in fact, altered and results in adaptations that obese individuals take to reduce the energy expenditure during locomotion.