Cheating on a Diet – Good or Bad?

In discussions about dieting, a topic that often comes up is “cheating”. Is it good or bad to cheat once in a while during a diet?

In order to answer this question appropriately, it is necessary to look at both the quantitative (how much) and qualitative (what) aspects of dieting, and the physiological and psychological responses they elicit.

Dieting – what are we really talking about?

In everyday speak, dieting usually implies both eating less calories (quantitative aspect), and eating or not eating “specific” foods (qualitative aspect). The dictionary definition of “diet” and “dieting” is “to eat and drink sparingly or according to prescribed rules” or “a controlled intake of foods, as for medical reasons or cosmetic weight loss”.

When considering the issue of “cheating” – which scientists call dieting consistency/inconsistency – and trying to answer the question whether it is a good or bad practice, it is important to distinguish these aspects of dieting.

Calorie restriction (food/drink quantity)
When reducing calories our bodies respond by lowering the basal metabolic rate (aka resting energy expenditure), and there is also a reduction is spontaneous physical activity. If the calorie restriction is severe, the body goes into starvation mode, which will further counteract any fat loss efforts. 1-2

Specific food restriction (food/drink quality)
A diet usually has an explicit (or implicit) list of foods that it recommends and foods that are no-nos. Eating specific foods or cutting out specific foods often has greater psychological consequences than calorie restriction per se. This is especially the case if you don’t like the foods that are part of your diet plan, or if you have a particularly strong preference for the forbidden stuff.

The different types of “cheating”
Now back to the issue of cheating. Looking at calorie restriction and specific food restriction separately, you see that that you can cheat in three different ways:
Eating more calories from the same “dieting foods” (quantitative cheating)

Eating “forbidden” foods, but still within your daily calorie allotment (qualitative cheating)

Eating “forbidden” foods and exceeding your daily calorie allotment (double whammy cheating!)

Dieting consistency is not yo-yo dieting!

Before we continue, I want to make clear that this discussion on diet cheating (dieting consistency) should not be confused with yo-yo dieting (aka weight cycling; when one is repeatedly losing and regaining weight). Yo-yo dieting definitely has detrimental effects, both physiologically and psychologically. 3, 4

Dieting consistency in this context is about maintaining the same diet regimen on weekends as on weekdays or about whether it is ok to have a one cheat meal during the weekend. For many people, diet and activity patterns differ substantially on weekends as compared to weekdays. If taken to the extreme, these kinds of cheat weekends can ruin the best diet weekdays.

Possible benefits and risk with cheating on a diet?
Allowing some diet flexibility on weekends, holidays, and vacations can reduce boredom, which is a known contributor to dieting lapses,5 and be more realistic from a long-term perspective. However, flexibility might also increase exposure to high-risk situations, which may contribute to loss of control. This is especially a concern for people with addictive personalities (you know it if you have a tendency to get hooked on things).6

What does research show?
While it is well documented that holidays are associated with fat gain,7-9 it wasn’t until recently that studies started to investigate the influence of weekend eating habits on short- and long-term body fat mass. The first study on weekend eating habits was done in National Weight Control Registry subjects who had successfully maintained a weight loss of at least 30 lb (13.6 kg) for 8 years.10 The purpose of the study was to examine if maintaining the same diet regimen across the entire week (including weekends) and entire year facilitates weight control, or if dieting more strictly on weekdays and/or non-holidays and relaxing the diet rules on weekends/holidays is better. It was found that subjects who reported greater dieting consistency across the weeks and year were more likely to maintain their weight within 5 lb (2.3 kg) during the subsequent year, whereas participants with lower dieting consistency scores were more likely to regain weight during the subsequent year.10 A more recent study, where subjects consumed on average 236 calories more on weekend days, confirmed that weekend dietary indulgences contribute to either cessation of fat loss or body fat gain.11 A particularly interesting finding is that as the duration of a consistent diet increases, a shift in the balance between the effort and pleasure of eating healthy dieting foods may occur, which makes it easier to stick to the diet and thereby improved the odds of keeping the flab off.12 This is supported by another study showing that repeated exposure to healthy (diet) foods over time elicits a preference for those foods. 13 In other words, a strong correlation exists between a person’s customary food intake (good or bad) and a preference for those foods. The key is to stick to the healthy (diet) foods long enough for this phenomenon to develop. From my own experience – I’m my own lab rat – I know this works.

Bottom Line?
Whether cheating on a diet is good or bad for you depends on your personal inclinations and the reasons for the cheating.

From a biological perspective, I believe quantitative cheating, when you eat more calories from the same healthy “dieting foods” can be a good thing, since it can prevent lowering your resting metabolic rate and drops in spontaneous physical activity, and enable you to exercise with much greater intensity.

When it comes to the other types of cheating, the consequences are more of a psychological origin. If you have an addictive personality, don’t even think about cheating. Remember, the best cure for any addiction is complete abstinence.

If you don’t have an addictive personality but have a lot of body fat to lose, it is ok for you to engage in quantitative or qualitative cheating on weekends. You have two options; either you can eat a cheat meal with “forbidden” foods but stay within your daily calorie allotment, or you can increase the serving size of your diet foods. From a health and performance perspective, it is smarter to eat more of the healthy stuff. If you chose a cheat meal, be mindful of the calories and only do this if you feel that it helps you stay on track for the rest of the week.

If you don’t have that much body fat to lose and are just dieting to get in a little better shape, you can indulge in a double whammy cheating meal on weekends, that is, eat a meal of “forbidden” foods AND exceed your daily calorie allotment. Just don’t go too much overboard; your body and mind will still take note of what you’re doing.

In any case, the reason for you to cheat on a diet – if you do – should be that it helps you to stick to in the long run. Not because other people coerce you into it or are trying to make you believe that you “have to” cheat on your diet to get stronger in the gym or lose body fat. That’s nonsense you often hear from folks who don’t have the willpower and discipline themselves to stick to healthy eating. Remember, there is no physiological need whatsoever to eat unhealthy stuff; there are no “pizza receptors” in the body. It has actually been shown that friends can have a larger impact on a person’s risk of gaining body fat (or failure to shed he flab) than genetic predisposition to fat gain.14 So don’t fall for peer-pressure and never engage in risky behaviors (foods or otherwise!) just because your friends do!

My advice to you is to be your own scientist and lab rat; try and see how you feel. Just be honest with yourself. If a cheat meal really helps you stick to your diet in the long run, go for it. But if you lose control you know cheating on a diet is not for you, and you better stick to your guns. However, a slip doesn’t have to mean failure; use the experience as a guide for your future dietary decisions and long-term fat loss success.

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About the Author: Monica Mollica

Monica Mollica holds a Master Degree in Nutrition from the University of Stockholm and Karolinska Institute, Sweden. She has also done PhD level course work at Baylor University, TX.

Monica is a medical writer and clinical website developer. She writes CME (Continuing Medical Education) materials for medical news organizations and medical communications for the pharmaceutical industry.

Being a fitness athlete herself, she is also sharing her hands-on experience by offering nutrition/health promotion consultations, and body transformation coaching.

Having lost her father in a sudden fatal heart attack at the age of 48 – caused by an unhealthy lifestyle – she is very passionate about health promotion and specializes in preventive medicine.

Monica is currently in the process of writing a book on testosterone, covering health-related issues for both men and women. You can visit her website at

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Disclaimer: This content is for informational purposes only and is not meant as medical advice, nor is it to diagnose or treat any medical condition. Please consult your physician before starting or changing your diet or exercise program. Any use of this information is at the sole discretion and responsibility of the user.