© 2014 by Taylor & Francis Group, LLC. Central to body weight regulation is the delicate balance between energy intake and energy expenditure, typically referred to as energy balance. The interest in physical activity (PA) as an important lifestyle behavior in part stems from the understanding that PA is a means to increase energy expenditure. PA behavior is in fact the largest modifiable component of energy expenditure and is assumed to be one of the major behavioral determinants affecting the dramatic increase in obesity over the past decades. According to definitions by the World Health Organization and Centers for Disease Control and Prevention (CDC), PA refers to all bodily movement produced by the contraction of skeletal muscle that substantially increases energy expenditure. Specifically, leisure- time physical activity (LTPA) is referred to as all physically active hobbies, exercises, and sports performed in one’s leisure time.