I’ve read that when you restrict your caloric intake by about 500 below maintenance, your metabolism can adjust to fewer calories and hold onto fat. The thyroid hormones play a major part.
In underfed individuals, there is a decrease in T3 and T4, which contributes to the downregulation of your metabolism. - so if you eat fewer calories, your body will attempt to balance energy expenditure by holding onto fat. A cheat day or strategic overfeed can help increase these hormones. A Sunday Food Funday where you eat “anything that doesn’t get up a tree quick enough” can literally help you get leaner in the long run. - It’s counter-intuitive, but gives a welcome break to the regiment of watching what you eat all the time.
We all have a go-to meal that does more for our soul than the best diet in the world would. Sometimes we need to go there. It's what makes us human.