Abstract: In one embodiment, the present disclosure provides a computer implemented method of determining energy expenditure associated with a user's movement. A plurality of video images of a subject are obtained. From the plurality of video images, a first location is determined of a first joint of the subject at a first time. From the plurality of video images, a second location is determined of the first joint of the subject at a second time. The movement of the first joint of the subject between the first and second location is associated with an energy associated with the movement.