Is it true that a cheat meal speeds up your metabolism and helps you lose weight?

There is a widespread belief that you should break your diet from time to time by allowing yourself sweets or fast food - this approach will not only relieve psychological stress, but also supposedly help you lose more weight. We found out whether this position is supported by scientific data.

The fact that cheat meals are useful for speeding up metabolism is stated in articles on websitesdedicated to bodybuilding and selling sports nutrition. Some fitness trainers they tell about this in their blogs, although others evaluate recommendations from colleagues skeptical. It is known that many celebrities are committed to the cheat meal concept. Thus, actor Dwayne (The Rock) Johnson, in his own words recognition, every Sunday allows himself burgers, cookies and sweets. Model Cindy Crawford prefers ice cream, chocolate and cocktails as a cheat meal, and the actor Ryan Reynolds - pizza.

A cheat meal (from the English cheat - “to deceive” and meal - “meal, dish”) is usually called a regular meal consisting of favorite but prohibited foods (for example, sweets, starchy foods, fast food or alcohol). Although sometimes even with a cheat meal it is possible to meet the planned number of calories, this practice usually leads to overeating. A concept that is similar in meaning is a loading day (aka cheat day) in the break between fasting days.

Research on the effect of cheat meals on metabolism was carried out back in the 1980s (although on very modest samples). Thus, observation of six healthy young men showed acceleration of metabolism by only 10%, which lasted only one day. Scientists attributed the metabolic changes primarily to weight gain that occurred due to eating too much on a fasting day. Another study (sample included six normal-weight and six overweight volunteers) demonstratedthat a single overeating (1000 additional kilocalories per day) increased metabolism by 6.6% in people with normal weight, had almost no effect on this process in those who were overweight, and slowed down the rate of metabolic processes by 9.1% in people with obesity. 

The phenomenon of changes in metabolic rate in response to changes in the energy value of food eaten called adaptive thermogenesis. It has been scientifically proven that if fewer calories enter the body, metabolic processes slow down after some time. This is why in the first days and weeks of the diet, weight comes off quickly, and then progress becomes less obvious. If the body receives an unusually large amount of calories at one time, metabolic activity, following the theory about the benefits of cheat meals, should increase.

In 2010, Dutch scientists held meta-analysis of studies on changes in metabolism during overeating. They examined 16 publications that analyzed the experiences of 185 volunteers. In five experiments, metabolism actually accelerated after overeating, but another 11 studies showed that the rate of metabolic processes, if increased, was extremely small. Summarizing the data obtained, the scientists suggested that in such cases the main reason for the acceleration of metabolism is not overeating itself, but an increase in body weight due to heavy food intake, that is, the body literally requires more energy to meet the needs of the “enlarged” body. In their opinion, a cheat meal is simply not effective in terms of weight loss - as soon as the weight returns to what it was before, the metabolism will also return to its previous level.

In a 2012 paper, scientists from the University of Washington let down results of a one-year observation of a group of 48 volunteers aged 50–60 years with normal body weight. Study participants were divided into three groups: one who exercised regularly, one who followed a diet with limited daily energy intake, and one who led a generally healthy lifestyle but did not practice either of these two weight control methods. After studying the diaries in which volunteers described their diet and physical activity, the scientists noted that the majority in all three groups ate especially a lot on Saturdays, including unhealthy foods (fatty and sweet). At the same time, those who did not have a cheat day on weekends achieved more significant weight loss than those who allowed themselves a cheat day. According to the researchers, on average, going beyond the diet on the weekend led to a gain of 0.077 kg by Monday morning. Although the figure seems insignificant, regular overeating on Saturday and Sunday over the course of a year can lead to weight gain of up to 4 kg.

In 2023, researchers from the University of New South Wales (Australia) studied the effect of cheat meals on rats. As part of the experiment, 48 individuals were divided into four equal groups: rats from the first group ate a healthy complete food, and rodents from the other three, in different orders, either ate the same food or switched to a diet high in sugar.

Breaks on unhealthy food, scientists found, led to the fact that bacteria associated with obesity actively multiplied in the intestines of rodents and strains of “good” microorganisms associated with weight control were inhibited. Moreover, no matter how often the diet was changed, all rats from the corresponding groups increased the risk of obesity. Moreover, in cognitive tests, rats that occasionally ate unhealthy foods performed worse than animals that ate a healthy diet. Alternating healthy and unhealthy diets according to a 5:2 or 4:3 scheme worsened rats have spatial memory.

In 2021, scientists from Rush University (USA) found that among people following a Mediterranean diet, cheat meals lead to faster cognitive aging. Over the course of nearly a decade, researchers analyzed the food diaries of 5,001 people over the age of 65. Those who did not deviate from the Mediterranean diet were 5.8 years “younger” in terms of cognitive function than those who indulged in unhealthy food regularly.

In 2022, Canadian researchers studied dietary habits of 2,717 people aged 16 to 30 who said they followed a diet. The researchers found that the practice of cheat meals is more common among men (60.9%) than among women (53.7%). According to scientists, men are more likely to try to gain muscle mass through diet and resort to cheat meals as a means of speeding up their metabolism. It turned out that busy days increase the risk of developing eating disorders. Women cheat meal practitioners were more likely to experience anorexia, fasting, bulimia, orthorexia, and binge eating disorder, while men were more likely to experience fasting, binge eating disorder, and exercise addiction.

At the same time, cheat meals can also provide important psychological relief. Experiment 2016 showed: Subjects who consumed 1,300 kcal for six days and could eat up to 2,700 kcal on the seventh were more motivated to maintain their diet compared to those who constantly limited themselves to 1,500 kcal. 

Nutritionist Kate Patton advises Do not focus on dividing food into “good” and “bad” and do not allocate a separate day or meal for unhealthy foods and dishes. In her opinion, a smarter approach is to structure your daily diet so that it consists of 80-90% healthy food, and the rest consists of treats. 

So, while a cheat meal may help some people on a strict diet maintain their motivation, it does not provide any other significant benefit. An acceleration of metabolism after overeating is observed in the vast minority of experiments; moreover, the metabolic rate increases slightly and quickly becomes the same. At the same time, loading days negate the results achieved by following a healthy diet and can lead to eating disorders.

Cover image: GPT 4O

Mostly not true

What do our verdicts mean?