‘Cheat’ days while on a Ketogenic Diet (KD)

The Ketogenic diet is a low carbohydrate, high fat normal protein diet. It is a therapeutic diet that has been used since the 1920s for treating uncontrolled epilepsy. Recently it is being tried in other medical conditions like cancers, Alzheimer’s disease, autism, and progressive MS. So can you ‘cheat’ for just one or a few days while on KD?

The festive season is here and the temptation to cheat just once while on the KD is immense. Following any diet is not easy and requires dedication and self-control. However, no one is perfect and many look for that one ‘cheat’ day. It could be a party, marriage function or festive day where they can free themselves from the strict rigors of the KD.

The person on a ketogenic diet cannot have a cheat day, especially those on KD for therapeutic purposes.

Ketogenic diet is a rigid/ restricted diet routine where the person has to follow a trained keto dietician’s instruction properly. There are different types of Ketogenic diets, namely: –

  • Classical KD
  • MCT KD
  • Modified Atkins’ diet (MAD)
  • Low glycemic index therapy (LGIT)
  • High PUFA KD

Ketogenic diet being a therapeutic diet is like a medication. Every medicine is given in a particular dosage in a particular strength and has to be followed as per recommendations of doctor for proper efficacy. Thus, KDs are designed and calculated individually by a trained keto dietician and neurologist team. In the classical KD each meal comprises the same calorie, fat, protein and carbohydrate content. So if you skip any of the meals or change the ingredients of the planned recipes it will affect the ketosis. Even the other KDs have a very limited leniency. Therefore, the way you take your medicines in the prescribed dosage and on time you should take your KDs.

Cheat days can lead to an acute fall in ketones and result in break-through seizure in those with epilepsy. A rapid change in blood sugar level can rarely lead to swelling in your brain (cerebral oedema). This complication appears to be more common in children, especially those with newly diagnosed diabetes.

Nowadays it is also used in weight loss programs. But the diet given in weight loss is more akin to an Atkins’ Diet which is also a low carbohydrate but has no quantification of the protein and fat content. Thus, it is different from the KDs and is more liberal.

Cheat days could actually be beneficial in a KD weight loss program but not for the KDs used for therapeutic purposes.

According to a new study from Australian researchers, taking cheat days, or breaks, while dieting may actually help aid weight loss. According to Nuala Byrne, the head of the University of Tasmania’s School of Health Sciences, Greater weight and fat loss was achieved with Intermittent Energy Restriction (IER). In this study, the superior weight loss seen in the INT group is in contrast with the majority of similar studies that have reported no advantage of intermittent over continuous ER. In one of the interviews, Byrne also points out that not just any break in dieting will be successful.  Seimon RV mentioned that the term ‘intermittent energy restriction’ has become almost synonymous with the term ‘intermittent fasting’, which consists of alternating 1- to 7-day periods of complete or partial food restriction (true or modified fasting), and ad libitum food consumption. Trepanowski JF et al, in a recent 12-month clinical trial and several other recent reviews have concluded that existing models of intermittent ER (largely versions of intermittent fasting), could be considered equivalent, but not superior, alternatives for weight loss. Basically these study concluded that obese subjects who tried alternate day dieting did not lose more weight that those who dieted continuously. 

So it is still controversial whether cheat days helps weight loss or not.



  1. NM Byrne et al.Intermittent energy restriction improves weight loss efficiency in obese men: the MATADOR study. International Journal of Obesity (2017), 1–10
  2. Seimon RV, Roekenes JA, Zibellini J, Zhu B, Gibson AA, Hills AP et al. Do intermittent diets provide physiological benefits over continuous diets for weight loss? A systematic review of clinical trials. Mol Cell Endocrinol 2015; 418 (Pt 2): 153–172.
  3. Trepanowski JF, Kroeger CM, Barnosky A, Klempel MC, Bhutani S, Hoddy KK et al. Effect of alternate-day fasting on weight loss, weight maintenance, and cardioprotection among metabolically healthy obese adults: a randomized clinical trial. JAMA Int Med 2017; 177: 930–938.
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