This human body established by God is like a factory established by an industrialist. The profit of the factory is divided in to three parts:
1) A part for the salaries of the workers,
2) Another part used to purchase the raw materials for the factory, and
3) The last remaining part to be submitted to the owner of the factory as profit.
Similarly, the energy released by the digestion of food should be also partitioned into
1) Energy consumed by the biological systems (workers) of the body like heart, lungs, kidneys, brain etc.,
2) Energy in the form of work done by the body to earn the food (raw material) necessary for conversion in to energy, and
3) The remaining last part of energy to be submitted to the owner of this body (God) in His service.
The factory needs some gap of rest so that constant work of machines results in deterioration of the efficiency. Hence, rest is needed for this body in regular intervals which should never be disturbed.
You may change the workers in shifts to run the factory continuously not minding the deterioration of the machines. In the body, you can’t do so because the biological systems can’t be changed in shifts.
You (soul) are the manager of this body-factory and you have no right to spend the profit of the factory in unnecessary ways and reduce the profit of the owner. The owner will not be pleased with you in such case. You submit the profit to the owner without any unnecessary wastage so that the owner (God) of this body-factory is extremely pleased with you and you are uplifted.