Maybe your first step will be to aim for being less rigid during the day? Not necessarily with your cereal ‘binge-food’, maybe just any kind of food?
My guess is this pattern of restriction in the day and overeating at night is driven by weight loss as the priority. If this makes sense to you, I hope you’re taking a good look at all the material in Week 1.
It’s not at all uncommon, by the way.