I am fascinated by the brain. Learning how it works is amazing and makes me feel normal. Seth Godin wrote a book called Linchpin where he talks about the Amygdala as our "Lizard brain". It's role is our survival. This part of our brain wants to take charge whenever possible. Unlike other animals we have advanced brain capabilities that allow us to think and reason in order to do more than just survive, to make progress and thrive.
These two parts of our brains (this is a huge oversimplification by the way) do battle when it comes to eating. You've experienced it. As a member explained to me this week, "I was eating the ice cream and kept thinking, 'why am I doing this?'", it sometimes feels like we're at war with ourselves. The lizard brain is only concerned with the moment - comfort right now, who cares about later.
One way to quiet the lizard brain is to keep junk food out of your environment. You know from experience that if it's there you'll eventually eat it - all of it - until it's gone. When it's gone, the urgency subsides.
The conflict is between what feels good now (the lizard brain) and what we ought to do to get what we really want in the future. Think about it and find ways to tame your amygdala.