Cheat Days During a Diet: Helpful or Harmful? How to Use Them Wisely

When you stick to a meal plan consistently, almost everyone eventually thinks, "I just want to eat whatever I want for one day." That is why many people set aside one cheat day per week. But does that one day ruin your diet, or can it actually help you keep going longer? In short, the answer depends on how you use it. The same cheat day can become a strategy that helps one person break through a plateau, while for someone else it becomes a trap that wipes out a full week of effort.

Why did the idea of a cheat day emerge?

Dieting is basically about creating a calorie deficit, meaning intake is lower than expenditure. Since 1kg of body fat is roughly equivalent to 7,700kcal, eating about 500kcal less per day would, mathematically, lead to about 0.45kg of weight loss per week, or 3,500kcal. But when the deficit continues for a long time, the body recognizes it as a food shortage and tries to conserve energy. The idea behind a cheat day began as a way to briefly raise calories, send the body a signal that "it is okay, we are not starving," and at the same time give you psychological breathing room so you can sustain the diet longer.

Benefit 1 — Leptin and mental recovery

When calories are restricted for a long time, leptin, the satiety hormone, decreases while ghrelin, the hunger hormone, rises, making you feel constantly hungry and increasing appetite. A day with enough carbohydrates may temporarily raise leptin and help calm runaway cravings. More important is the psychological effect. The pressure of thinking you must eat only chicken breast forever can easily lead to binge eating or giving up on the diet, but having a planned reward day can help you stick to the other 6 days more consistently.

The downside — One day can erase a week’s worth of effort

The problem is calories. For example, suppose you have accumulated about a 3,000kcal deficit over 6 days by eating 500kcal below maintenance each day. But on a cheat day, if you add pizza, beer, and dessert to a whole chicken, about 1,800kcal, it is common to eat 2,500–3,500kcal more than usual. Then the entire weekly deficit disappears, and the scale stays the same or even goes up. Much of that is water from carbohydrates and sodium and may drop within a few days, but the mental shock can be significant. The word "cheating" itself carries guilt, as if you are breaking rules, which can also trigger a cycle of bingeing, self-blame, and more bingeing.

Cheat day vs. refeed day: What is the difference?

That is why these days, a refeed day is often recommended over cheating, meaning unlimited eating of anything. A refeed is a planned eating day when you intentionally increase calories, especially carbohydrates, by a set amount. For example, someone who usually eats 1,600kcal might raise intake only to their maintenance calorie level, or TDEE, of 2,000–2,200kcal for the day, with a higher proportion coming from carbohydrates. The key is that it is not unlimited bingeing, but a bounded recharge.

Know your maintenance calories first

To use a cheat day strategically, you need to know your TDEE, or total daily energy expenditure. First, calculate your BMR, or basal metabolic rate, using the Mifflin-St Jeor equation. For example, for a 30-year-old woman weighing 60kg and 165cm tall, BMR ≈ 10×60 + 6.25×165 − 5×30 − 161 ≈ 1,320kcal. Multiplying this by an activity factor, about 1.4 for light activity, gives a TDEE of about 1,850kcal. In other words, this person’s approximate "level at which eating does not lead to weight gain" is 1,850kcal, and using this as the baseline even on a reward day can help prevent overeating.

5 principles for using cheat days wisely

• Keep the frequency to no more than once a week, and try reducing it from a full day to a single meal. One reward meal can be enough to feel satisfied.
• Set a limit. Instead of unlimited eating, aim for maintenance calories ±0 or only +300–500kcal above usual intake.
• Place it on a day when you have exercised a lot. After strength training, increased carbohydrates are more likely to replenish muscle glycogen and less likely to be stored as fat.
• Keep protein intake the same as usual, about 1.2–1.6g per kg of body weight during a fat-loss phase. Skipping protein just because it is a cheat day increases the risk of muscle loss.
• Do not fast the next day to "make up for it." That only creates a reward → fasting → binge cycle. Simply return naturally to your usual eating pattern.

Who cheat days may not suit

Cheat days are not a cure-all. They can do more harm than good for people who tend to binge and find it hard to stop once they start eating, or for those who often use "today is a cheat day" as an excuse and fall off their plan several days a week. In such cases, it is more sustainable to skip separate reward days and instead include a small amount of one food you enjoy every day, such as a piece of dark chocolate or a handful of fruit, reducing the sense that dieting is all about enduring restriction.

In summary, a cheat day is neither inherently harmful nor helpful. If it starts with guilt and ends in bingeing, it becomes harmful by erasing a week of effort. But if you know your maintenance calories, set limits, and use it as a planned recharge, it can help you manage both appetite and mindset. In the long run, a diet built on 80% discipline and 20% flexibility beats one where you restrict perfectly until you explode.

※ This article is for general informational purposes only and is not medical advice. If you have an underlying condition such as diabetes or thyroid disease, or if you are pregnant or breastfeeding, consult a physician or nutrition professional before changing your diet.