From one perspective, a human being can be seen to be comprised of a soul and a body. Although the nature and the function of each of these faculties are mainly different, they do seem to affect each other. In particular, it seems that the way we manage and maintain our bodily needs has some direct or indirect effects on our soul. There is a well known recommendation from many pious religious figures that we should avoid eating excessively. The general advice is that in principle, we should only eat when we feel hungry and that, we should aim to not make ourselves completely full.
A full stomach hardly allows a mood required to generate a spiritual experience through worship and meditation. An excessively full stomach makes the person lazy and not keen to take benefit of any constructive opportunities. To give a more tangible example, it will certainly be more difficult to wake up for Tahajjud (night prayer) or morning prayer if we go to sleep in a state where we can hardly breath, due to the amount of food we have consumed.
This is not an advice to adopt the practices of those who go to extremes in controlling their desires. This is simply to say that if we make our stomach a graveyard for animals, we cannot then expect our soul to be able to easily soar close to the pinnacles of spirituality.
(Dr Abdullah Rahim)