Primal Brain vs Prefrontal cortex

I am listening to the teachings on the urge jar… I have discovered a question I am asking myself and not really knowing how to navigate it. I haven’t done a model on it as its quite overwhelming so I am typing and breathing!

What causes our primal brain to want a reward…I have unconsciousness thoughts here as I struggle with not wanting to eat the chocolate I am putting into my mouth….

I lost 58 lbs in 2007 and up until 5 years ago I ate clean and healthy. A life situation that blew me away causes me to say to myself a little chocolate will be okay. I only put on 10 lbs because I could control it and now all I want to do is eat that which the primal brain wants. I am not giving in however, I am still doing all the training I was and now have a few other health challenges that have caused me to learn about myself that I am only 800 calories a day, no appetite and won’t eat more food because I can’t find the thought which feels like answer to my dilemma.

I am not asking for health advise here, I am finding an equal level of stimulus on both these functions of the brain. I want to find the thought!