Cheat Days While Dieting: Poison or Medicine? How to Use Them Smartly

When you've been sticking to a meal plan for a while, almost everyone eventually thinks, "I just want to eat freely for one single day." That's why many people set aside one 'cheat day' per week. But is this one day a poison that ruins your diet, or a medicine that helps you keep going for the long haul? To get straight to the point, the answer depends on 'how you use it.' The very same cheat day can be a strategy that breaks through a plateau for one person, and a trap that reduces a week's effort to zero for another.

Why was the concept of the cheat day created?

Dieting is fundamentally about creating a 'calorie deficit (intake < expenditure).' Since 1kg of body fat is equivalent to about 7,700kcal, eating about 500kcal less per day arithmetically results in losing about 0.45kg (3,500kcal) per week. But when the deficit drags on, our body perceives it as a 'food shortage' and tries to conserve energy. The cheat day started from the idea of briefly raising calories here to send the signal 'it's okay, we're not starving,' while also providing psychological breathing room so you can sustain the diet longer.

Benefit 1 — Leptin and Mental Recovery

When you restrict calories over a long period, the satiety hormone 'leptin' drops and the hunger hormone 'ghrelin' rises, leaving you constantly hungry with a stronger appetite. A day of consuming plenty of carbohydrates can temporarily boost leptin and help calm a runaway appetite. More important is the psychological effect. The pressure of 'nothing but chicken breast forever' tends to lead to binge eating or giving up on the diet, but having a planned reward day helps you stick to the other 6 days better.

The downside — A single day erases a whole week

The problem is calories. Suppose you've banked about 3,000kcal over 6 days at a 500kcal daily deficit. But on a cheat day, it's common to eat 2,500–3,500kcal more than usual once you add a whole fried chicken (about 1,800kcal) plus pizza, beer, and dessert. Then the entire week's deficit vanishes, and the scale stays the same or even goes up (a large part is water from carbs and sodium, so it drops within a few days, but the psychological shock is big). The very word 'cheating' carries the guilt of 'a trick or a foul,' which can also trigger a vicious cycle of self-blame after a binge → another binge.

Cheat day vs. refeed day: what's the difference?

That's why these days a 'refeed day' is recommended over 'cheating (anything, unlimited).' A refeed is a planned eating day where you intentionally increase calories—especially carbohydrates—by a set amount. For example, someone who usually eats 1,600kcal raises it only up to their maintenance calorie (TDEE) level of 2,000–2,200kcal, increasing the proportion of carbs within that. The key is that it's not unlimited bingeing but a 'recharge with a limit.'

You need to know your maintenance calories first

To use a cheat day as a strategy, you need to know your TDEE (Total Daily Energy Expenditure). First, calculate your basal metabolic rate (BMR) using the Mifflin-St Jeor equation. E.g., 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 (light activity is about 1.4) gives TDEE ≈ 1,850kcal. In other words, this person's 'line where eating won't add fat' is about 1,850kcal, and using this as a baseline even on a reward day can prevent things from spiraling.

5 principles for using cheat days wisely

• Keep the frequency to once a week or less, and try shrinking it from a 'day' to a 'single meal.' One reward meal is enough to feel satisfied.
• Set a limit. Not unlimited, but only up to 'maintenance calories ±0' or +300–500kcal above usual.
• Schedule it on a day with a lot of exercise. After strength training, the extra carbohydrates are used to refill muscle glycogen and are less likely to turn into fat.
• Keep protein as usual (about 1.2–1.6g per kg of body weight during a cutting phase). Skipping protein just because it's a cheat day increases the risk of muscle loss.
• Don't 'make up for it' by starving the next day. That only creates a vicious cycle of reward → fasting → bingeing; just return naturally to your usual meal plan.

Cheat days don't suit these people

The cheat day isn't a cure-all. For someone with a binge tendency who finds it hard to stop once they start eating, or someone who frequently uses 'it's a cheat day today' as an excuse and crumbles for several days a week, it's actually a poison. In such cases, rather than setting aside a separate reward day, it's more sustainable to include a small amount of one favorite food in your daily meals (e.g., a piece of dark chocolate, a handful of fruit) to reduce the 'diet of deprivation' itself.

The success or failure of a cheat day depends not on 'how much you eat' but on 'how much you eat within control.'

To sum up, a cheat day is neither poison nor medicine. If it starts with guilt and ends in bingeing, it becomes a poison that erases a week of effort; but if you know your maintenance calories and set a limit to use it as a 'planned recharge,' it becomes a medicine that manages both appetite and mindset at once. Rather than starving perfectly and then exploding, a diet that goes the distance with 80% discipline and 20% leeway ultimately wins.

* This article is reference material for general information purposes only and is not medical advice. If you have a chronic condition such as diabetes or thyroid disease, or are pregnant or breastfeeding, consult a doctor or nutrition specialist before changing your diet.