Don't Panic !! It's only Christmas dinner !
You're not a bad person or an unhealthy one if you do happen to over eat today. Remember, this is just ONE day out of 365 days in the year. If you're eating right most of the time, over eating once in a while will not harm your long term efforts at good health or weight loss.
I'll admit it. I'm recovering from yesterday's food coma. I won't even list all the food and goodies I ate. I'm not worried that I'll gain weight. I don't eat like this every single day. I couldn't. My poor stomach couldn't take it ! LOL !!
The point ? If you over eat today, don't beat yourself up. Try to be mindful, but if you're not too mindful, you just do your best to eat more normally tomorrow.