Question

How does energy get wasted by sitting without working

Answer 1

Energy is getting wasted by sitting without working.Work and energy are relative terms.
practically speaking work is done only when the force applied moves the body.But in the case of sitting there is no movement.so work is zero but still energy is being wasted.It is spent on a cellular level. Muscles are made with filaments which can slide relative to one another, these filaments are connected by molecules called myosin, which use up energy to move along the filaments but detach at time intervals to let them slide. When you keep your body in position, myosins hold the filaments in position, but when one of them detaches other myosins have to make up for the slight relaxation locally. Chemical energy stored within your body is released by the cell as both work and heat.
Ultimately, the work done by the cells is actually done on other cells, which eventually dissipates into heat due to friction and non-elasticity. So all the energy you spend is invested in keeping the muscle tension and eventually dissipated as heat.