The concept of “cheat days” has been around from the day dieting was invented. Most dietitians and health coaches see a cheat day as a helpful tool to aid their clients “blow off steam” in an otherwise restrictive diet. The assumption is that the psychological boost of the cheat day is far greater than the damage done by a few extra calories.
However, this logic is flawed for several reasons.
1. Daily Suffering. In order to maintain prolonged weight loss, a dieter’s everyday eating pattern should not be deemed so miserable as to regularly warrant a day off.
2. Calorie Math. Most people are terrible at estimating the caloric content of foods they eat. Taking a day off can easily lead to an excess intake of 3000-4000 calories (see below). To lose a pound of weight, you need to create a deficit of 3500 calories. That’s 500 calories a day, for a one pound weekly weight-loss. Let’s say you were doing great for 6 days and managed to remove 3000 calories from your diet (6 days times 500). Today is your cheat day and all bets are off. You eat without counting and create a surplus of 3000 calories. Boom! Your overall weekly calorie deficit is 0 calories. No weight loss.