Well, I feel for you. As an example....if you add high quality petrol to your car and it runs like a champ....then you start putting Coca Cola in it.....there will be a problem. Your body is used to eating cleaner, and now you're torturing it. If you are able to stop at 1--so the much better for your system.
I have been trying to subscribe to the "fact" that a calorie is a calorie is a calorie. I've googled it, read about it, reviewed the scientific studies--and they do state that no matter the diet's composition, it boils down to the superior calorie, regardless. However, there's a difference between losing weight on 1300 daily calories no matter what sources they come from, and a body getting used to eating very healthfully, then loading it with junky sugar. The body will protest.
Being type 2 diabetic, I know a few cookies and a bunch of candy is going to make me feel. Sick. I don't need any reminders....
You're feeling the repercussions of the choices you made, but it is doubtful those choices will show up on the scale if you stayed within your calorie range -- at least that is what all of the studies have stated.
Do yourself a HUGE favor.
Remember how the junk is making you feel. That in itself may be enough to assist you in deciding to NOT eat it.
Years ago, I noticed a correlation between eating chocolate covered cherries and how it made me feel. So, as a treat, about every 6 months to a year when I was at this particular NJ Mall, I would purchase a half dozen and eat them over the course of a day. It didn't matter if I ate 1 or 6--the result was I was sluggish, gassy, sick to my stomach, got a headache, etc. It seemed worth it to me for once or twice out of the year to indulge in something so delicious. I had no idea that I was pre-diabetic at the time. Looking back to that, and over indulgences of sweets at holiday parties, it all makes sense. I don't like feeling that way. I don't want to feel that way. I know my limits!
If you liken that sick feeling to the source of the food, maybe that will help you to stop it. Good luck and happy holidays to you.