What happens on ONE day doesn't really make much difference over-all. If it did, a LOT of us who have reached out goals would be right back where we started, or at least, well down that track again.
I am one who in weight-loss mode practiced eating whatever I wanted one day in a two week period. Sometimes those calories were more than double my normal daily allowance. What I did most of the time was eat toward the lower end, so that with the over-eat day taken into account, I was still eating in weight-loss mode. Of course, sometimes that one-day-in-two-week period was extended, and sometimes it came a wee bit sooner. Since I reached my goal, I still mostly eat in weight-loss mode, but now give myself permission to eat whatever I want one day in a week. Again, sometimes it may be more than a week before I 'over-eat'. I have been at my goal for nearly 3 years.
It sounds to me like you are confused about calories/fats/etc. overall.
Below is are some links that may be helpful: www.sparkpeople.com/resource/motivation_ar