,regionOfInterest=(1042,736)&hash=058e6b5e3028d64bac76d7f855c42a1446e44a2e65b00b8c7d1dbc2c57196230)
A “cheat day” is intended to stimulate a slow diet metabolism. However, science shows that the benefits are minimal and the risks are high.
One day a week when all diet rules are abolished: pizza, ice cream and chocolate without limit. The so-called “cheat day” is a popular concept in the fitness and diet community. The promises sound tempting: A massive calorie surplus should stimulate the metabolism that has been slowed down by the diet, regulate the “fat storage hormones” and at the same time offer a mental break from the strict diet. But what actually happens in the body when there is such a calorie excess?
Tim Hollstein works as a senior physician and metabolic researcher at the University Hospital Schleswig-Holstein in Kiel. There he researches the secrets of human metabolism. He is part of our EXPERTS Circle. The content represents his personal opinion based on his individual expertise.
Scientific background
Table of Contents
If the body receives less energy than it consumes over a longer period of time (calorie restriction), it reacts with an evolutionary sensible protective measure: metabolic adaptation. The basal metabolic rate falls more than would be expected due to the loss of body mass alone. The body switches into energy saving mode to ensure survival in a supposed period of hunger. A central player in this process is the hormone leptin, which is produced in fat cells. Leptin signals satiety to the brain and regulates energy consumption. During a diet, leptin levels decrease, leading to increased hunger and reduced energy expenditure. The rationale behind a cheat day is the assumption that a short-term, massive calorie surplus – especially from carbohydrates – will cause leptin levels to rise again and signal to the body that the “famine” is over.
What does cheat day really bring?
However, the scientific data on the physiological effects of cheat days is rather sobering. Short-term overeating actually leads to an increase in leptin levels and a slight increase in energy expenditure – in science we call this “food-induced thermogenesis”. However, this effect is temporary and has little clinical relevance to long-term weight loss. The fact is: Short-term massive overeating increases energy consumption by a maximum of around 3 to 10 percent for a period of 24 hours. This minimal increase in no way compensates for the perhaps 1000 to 2000 additional calories consumed on an uncontrolled cheat day.
But “cheat days” can make sense if you eat in a controlled manner on these days and don’t exceed your calorie goal. This was shown in the MATADOR study (Minimising Adaptive Thermogenesis And Deactivating Obesity Rebound), in which two-week diet phases alternated with two-week “cheat weeks” (without calorie surplus!). This structured approach actually led to a smaller drop in basal metabolic rate and more efficient weight loss compared to continuous dieting. However, an uncontrolled, one-day cheat day does not achieve this effect. A recent review also shows that cheat meals can reduce the feeling of hunger in the short term, but do not cause a significant weakening of metabolic adaptation. Furthermore, the concept poses significant psychological risks. Categorizing foods into “allowed” and “forbidden” and eating uncontrollably on a given day resemble the patterns of binge eating disorder. It can lead to an unhealthy relationship with food, feelings of guilt and a yo-yo effect.
Every metabolic type reacts differently to “cheat days”
The reaction to overeating is also very individual. In our research at the National Institutes of Health (NIH), we were able to show that people have different “metabolic types.” People with frugal metabolisms greatly reduce their energy consumption when they restrict calories and hardly increase it when they overeat. “Waste types,” on the other hand, adjust their metabolism less strongly. A cheat day is particularly counterproductive for a “thrifty person” because the excess calories are almost entirely stored as fat without significantly increasing the metabolism. Instead of uncontrolled cheat days, the concept of “diet breaks” or “refeeds” is more scientifically based. Here, the calorie intake is specifically increased to the maintenance level (eucaloric) for a few days to weeks, often with a focus on carbohydrates in order to replenish the glycogen stores in the muscles (see MATADOR study). However, this happens in a controlled manner and without a massive calorie surplus.
Controlled diet breaks make more sense than cheat days
An uncontrolled cheat day doesn’t make sense from a metabolic physiological point of view. The minimal increase in energy expenditure does not justify the massive calorie surplus that can wipe out an entire week’s worth of diet success. If you want to give your body and mind a break, you should take structured, controlled diet breaks at a maintenance level instead of falling into extreme binges.
