My professional training is in thought processes; particularly brain functions and behavioral effects before, during and after a life altering personal or collective event.
Apologies in advance for the long winded response but, I think you may find it helpful.
Cannibalism though is an issue though not an initial focus. Here is why.
FIRST you will have to survive "the takers" especially in a city setting, you will have a more significant portion of the population who are of the mindset of being provided for.
The washing machine breaks, call a repair service. The lawn needs mowing, hire a service. Don't have time to cook, eat out. Ran out of milk, oops! No big deal, a supply is just up the block.
Planning ahead, learning to do for yourself is much less of a necessity than it is an inconvenience.
Fast forward to TEOTWAWKI (the end of the world as we know it).
At first. most people will be confused and desperate for information as to what is happening. If that is not available, rumors will rule the day. And, like a child's game of telephone, morph into nonsensical chaos. This will unnerve people who will then begin to panic.
Groups tend to feed off of each other and mimic observed behaviors. Three people appear to be running away from something, others join one by one until you have a huge group running for their lives, most of whom, have no idea what they are running from. They just assumed the others did.
They will start to empty shelves spending what ever cash they have. Then, as they realize that the issue is not quickly resolving and the supplies are going to be insufficient, turn next to the government, looking for salvation. When that is not forthcoming, they will begin to loot stores and warehouses taking their "fair share" while they can.
The time frame for this to happen is estimated to be about 72 hours. There will be sporadic violence prior to this but, as long as law enforcement is functioning, the sewage is not backing up and there is water in the taps, it will not be en-masse for a short time.
Once the looted resources have dwindled down again (an additional 24-48 hours) and no remedy or explanation is forthcoming, you will start to see individuals start taking from other individuals. Break ins, muggings etc.
After this point, you will start to see more organized raids taking place. The gang elements found throughout this nation, even in the rural areas but far more populous in cities, will coalesce and organize. They will realize quickly that the ones who hold the resources (food), hold the power. This will fester and grow and when the local government collapses because the police and politicians have decided they must care for their own families, these gangs will be the new government, which people desperate to feed their families will gladly pledge their allegiance. to.
This stage will continue for weeks and months as pets and livestock are taken and slaughtered for consumption. There may be some small groups of individuals that turn to eating human flesh early on, but they will not be organized for some time because of the social stigma attached to it.
Your main concern will be surviving the organized gang elements which will be heavily armed and ruthless, just as they are now. If you survive that long, you will be a hardened warrior and a group of cannibals will be little more than a nuisance.
