Physical activity level is a measure of the relative amount of energy an individual consumes performing physical activities and maintaining essential body functions. Individuals can be classified to low, moderate and high levels of activity, based on the amount of time they spend walking briskly (or performing an equivalent physical activity) on a daily basis. Individuals with low physical activity levels expend most of their energy maintaining essential functions, while those with high physical activity levels expend the majority of their energy performing physical activities.

For more information see How the Body Burns Calories