What I discovered (to be true for me) during spiritual seeking is that I was leaving myself to find myself. This is psychological splitting. My situation seems to be the common one of being a physiologically healthy person with a "personality disorder" - in other words, maladjusted but curable.
To use Freud/Jung's description, the ego (the conscious rational mind) mediates between the id (the primal drives for survival and satisfaction) and the superego (the ideal self, the moral self, personal god). When the superego and the id are in conflict, the ego cannot reconcile them and suffers tremendously.
An integrated, psychologically healthy person will create and accept values in the superego that accept and satisfy the id. The ego will maintain balance between them.
I think that religion and spiritual disciplines can create integration, but most people don't "finish the job." They split off the superego (god, heaven, love) and id (mankind, earth, evil) to relieve conflict in the ego, but they do not attempt to then reconcile and internalize them.
Monotheistic religions (and modern civilization is based on a monotheistic world-view) as practiced seem to actually create further imbalance by making the superego totally good and the id totally bad. Obviously, a person will not be able to achieve integration in this system.
If a person was to advise others to withhold nourishment it would seem crazy, yet when it is recommended as a means to leave behind the "bad" id (mankind, earth, evil) and live with only the superego (god, heaven, love), it's incredibly attractive to anyone who is having psychological conflict that the ego cannot mediate.
The person who has learned that being hungry, powerful, vital, and effective is "bad" has learned that the id is bad. It's one thing to be hungry, to steal food, and to feel bad about having stolen; it's another thing entirely to feel that being hungry itself is bad.
The origins of the "bad id" are usually instilled in childhood, beginning in infancy, and are both cultural and personal. Other traumatic experiences can cause this as well. Further damage is done by reinforcing the badness through the superego, such as teaching that maltreatment is deserved.
Psychotherapy and spiritual disciplines are healing when they redefine both the id and the superego in a way that enables them to be the poles of one continuum so that the ego can mediate between them. Ritualistic killing of animals is a primitive means to do this: I kill this conscious being to satisfy the id but I do it with honor to satisfy the superego.
In the case of veganism, striving to die and shed the id while striving to survive are opposed and represent a personality split (this is of course the opinion of someone who believes that animal foods are necessary for health - it's what I found to be true for me).
Healing a personality disorder requires accepting things that are highly intolerable, such as the sensations surrounding child abuse or becoming conscious of past actions that bring incredible shame. Not easy to do, which is why personality disorders are so powerful and difficult to correct.
Once I'd accepted certain things I was able to realign my superego (values) and accept my id (you can't change your biological drives, only suppress them) I was able to abandon ascetic (restrictive) practices and care for myself properly by mediating between them with the rational egoic mind. I'm still working on it - and perhaps we should all always be working on it, because to adapt and create is to be alive.
Why society as a whole seems to be disordered I really don't know, but from my perspective there is a learned repugnance for nourishing food (denial of the id) in preference for non-foods or restrictive eating habits that appeal to the superego.
This is, of course, just my point of view and my own experience. There is nothing to be lost and much to be gained by each person making their own respectful and moderate exploration of "what it means to be alive."
I hope your inner turmoil is soon replaced by inner peace!