Diet 6 days a week, and on the seventh eat absolutely anything. What’s not to love about that? Apparently, a lot. The idea of a “cheat day,” or a chosen day off from strict dieting, stirs up some serious debate in the health world.

So we went to the root of the issue: Can choosing to cheat actually be healthy?

There are generally three beliefs about what constitutes “cheating” on your diet:

  • Focusing on a specific time frame: the idea that cheating means eating anything during a set period (one meal, one day, etc.)
  • Cheating on occasion: eating specific things you’d usually avoid for health reasons, like fructose to prevent a glucose spike, caffeine to boost energy, and so on
  • Intuitive eating: accepting that cheating is a natural part of dieting and therefore isn’t really “cheating” at all, says Lindsey Joe, RDN

What goes on in your body on a cheat day depends on what you’re eating, how much, and how often. Let’s break down the science.

For a few decades, researchers have known that restricting calories (as most people do when dieting) can cause leptin to dwindle. Pratley RE, et al. (1997). Plasma leptin responses to fasting in Pima Indians. DOI: 10.1152/ajpendo.1997.273.3.E644

Leptin is important because it balances your energy and signals to your brain when it’s time to stop eating (no fourth slice of pie, thanks). Jéquier E. (2002). Leptin signaling, adiposity, and energy balance. DOI: 10.1111/j.1749-6632.2002.tb04293.x

Those in the pro-cheating camp say a cheat day can resupply your body with some much-needed leptin and boost your metabolism. But research on the subject is still mixed.

A study back in 1986 suggested that overfeeding (the scientific phrase for eating too much, which matches some people’s idea of “cheating”) isn’t actually worth it, because it only boosts metabolism between 3 and 10 percent for no more than 24 hours. Katzeff HL, et al. (1986). Metabolic studies in human obesity during overnutrition and undernutrition: Thermogenic and hormonal responses to norepinephrine. DOI: 10.1016/0026-0495(86)90119-8

But a decade later, research showed that temporarily upping calorie intake could re-up leptin production by nearly 30 percent — three times as much as previously thought — for up to 24 hours. Dirlewanger M, et al. (2000). Effects of short-term carbohydrate or fat overfeeding on energy expenditure and plasma leptin concentrations in healthy female subjects. DOI: 10.1038/sj.ijo.0801395

While the jury is still out on the leptin debate, there is some new research to suggest that cheat days are not all that bad physically — and may actually be good for your diet plan.

A 2018 study divided obese men into two groups. The first group stuck to a strict meal plan, while the other took intermittent breaks from the diet. After 4 months, the intermittent dieters had dropped more weight — and they gained back fewer pounds post-trial. Byrne NM, et al. (2018). Intermittent energy restriction improves weight loss efficiency in obese men: The MATADOR study. DOI: 10.1038/ijo.2017.206

Sounds good to us, but you may still want to limit your cheat meals. A 2017 study on rats found that 3 cheat days a week had the same effect on gut bacteria as a steady diet of junk food. Kaakoush NO, et al. (2017). Alternating or continuous exposure to cafeteria diet leads to similar shifts in gut microbiota compared to chow diet. DOI: 10.1002/mnfr.201500815

It’s also vital for anyone with a health condition (like diabetes, high cholesterol, or high blood pressure) to plan cheat days carefully since even small deviations from your diet can have larger health effects.

There’s a special caveat for keto dieters. A 2019 study found that even one dose of simple carbs on a cheat day was enough to damage blood vessels. Arrivederci, pasta. Durrer C, et al. (2019). Short-term low-carbohydrate high-fat diet in healthy young males renders the endothelium susceptible to hyperglycemia-induced damage, an exploratory analysis. DOI: 10.3390/nu11030489

Overall, consider the balance of macronutrients in any food. Sweets may be fine, but look for those that are also high in essential nutrients like protein and fiber, explains nutrition researcher and sports nutrition expert Douglas Kalman, PhD.

There’s a whole other side to the cheat day equation: psychology. What does a cheat meal (or day) do to your brain?

Psychologists and nutritionists often believe that using a cheat meal or cheat day to satisfy a craving can help people stick to otherwise restrictive diets, Kalman explains.

Some research agrees. A 2016 study found that dieters who occasionally strayed from their meal plans felt better about the diet process and stayed motivated to lose weight. It’s worth noting, though, that participants still kept portions in check on cheat days. Coelho de Vale R, et al. (2016). The benefits of behaving badly on occasion: Successful regulation by planned hedonic deviations.

The key, according to Joe, is getting past the idea of assigning “good” and “bad” labels to foods. Rather than turning a minor slip-up into a major backslide, she says, cheaters should simply accept what they’ve eaten and continue with their diet as planned.

Science backs this up. In a 2014 study, people who associated chocolate cake with celebration lost more weight than those who felt guilty about eating it. Maybe it’s time to stop calling cheat days “cheating” and start calling them “enjoying” or “celebrating” food. Kuijer RG, et al. (2014). Chocolate cake. Guilt or celebration? Associations with healthy eating attitudes, perceived behavioural control, intentions and weight-loss. DOI: 10.1016/j.appet.2013.11.013

No-holds-barred bingeing, however, can be dangerous and may even set off a problematic psychological chain reaction.

Think about it: Designating only one day a week to shovel sweets into your mouth may lead to an “all or nothing” mentality, where you overeat not because you want to but because you know you won’t get to again for a whole week.

In fact, a 2018 study showed that the psychology around cheat meals may be similar to that of bingeing episodes, but more research is needed in this arena. Murray SB, et al. (2018). Cheat meals: A benign or ominous variant of binge eating behavior? DOI: 10.1016/j.appet.2018.08.026

So, if you want to eat without psychological repercussions, listen to your body. What are you really in the mood for? Focus on quenching one craving at a time rather than opting for a full meal (or day) of unhealthy foods.

This is called intuitive eating or being mindful about what you consume. A 2017 literature review showed that mindfulness-based eating approaches may prevent weight gain. Warren JM, et al. (2017). A structured literature review on the role of mindfulness, mindful eating and intuitive eating in changing eating behaviours: Effectiveness and associated potential mechanisms. DOI: 10.1017/S0954422417000154

Feel like cheating? Here’s a summary of what we’ve covered:

  • There are a lot of different ways to think about cheat days, from free-for-alls to a simple psychological paradigm shift.
  • A brief window of overeating may increase your body’s leptin production, which in turn boosts your metabolism, but the science on this is still mixed.
  • Newer research suggests that a cheat day here and there may actually aid weight loss, but how often and how much food you eat may be the key.
  • Pay attention to how cheating feels. Ask yourself: Are you eating because of a scarcity mindset, or are you genuinely enjoying the food?
  • Shift your language from “cheating” to “celebrating” to stay on track with your goals.

Remember that you’re a human (not a robot). We recommend that you do whatever works best for you — just be mindful of your body and your mindset in the process.

If today that looks like a bacon cheeseburger with sweet potato fries after a solid week of kale salads, bon appétit.

Photo by Caitlin Covington.