Simply put, a refeed day is a planned increase in calories for one day on a weekly or biweekly basis. It's intended to give your body a temporary respite from calorie restriction.

Should you refeed on a rest day?

Have your refeed on a rest day

So a Sunday afternoon nap is often the order of the day, thus enhancing the restorative and recuperative qualities of a properly planned refeed.

Is a refeed day a cheat day?

Reefed Day vs Cheat Day

A refeed day is designed to replenish your leptin levels after a period of calorie suppression due to dieting. Cheat days are typically a day where all dietary guidelines are removed and you can eat anything you'd like.