‘Keto-flu’: Flu-like symptoms reported within several days of starting ketogenic diet

By Flora Southey contact

- Last updated on GMT

 ©GettyImages/OlgaMiltsova
©GettyImages/OlgaMiltsova

Related tags: keto, ketogenic, Flu

A fresh study has revealed the flu-like symptoms experienced by newcomers to the ketogenic diet, which researchers say dwindle after four weeks.

The ketogenic – or ‘keto’ – diet is low-carbohydrate, moderate-protein, and high fat. The diet produces elevated levels of ketones in the blood, which can be used as an alternative fuel when sugar levels are low.

Ketones are produced in the liver from fat, which has contributed to the diet’s growing popularity amongst those wanting to lose weight.

From a medical perspective, the effectiveness of the diet has only been established for intractable epilepsy. Aside from weight-loss, a ketogenic diet is also often self-administered for cognitive and memory enhancement, type II diabetes, or cancer.

However, following ‘keto’ has been associated with flu-like symptoms within the first few weeks of the diet.

Now, a fresh study has analysed the pattern, severity, and time course of these symptoms, as reported in posts by users of online forums.

The so-called ‘keto-flu’

The ‘transient’ symptoms (or side-effects) of the ketogenic diet are frequently referred to as ‘keto flu’.

Common symptoms such as flu, fatigue, nausea, dizziness, decreased energy, feeling faint, and heartbeat alterations may lead people to cease the diet prematurely, or be misdiagnosed by medical professionals – which could lead to unnecessary medical interventions.

“The experiences of symptoms by many people strengthens the evidence for side-effects following the initiatives of a ketogenic diet,” ​according to co-author Dr Emmanuelle Bostock, from the University of Tasmania’s Menzies Institute for Medical Research.

“These consumers have the most immediate experience of effects and side-effects and many choose to report and share these in online forums.”

Together with colleagues in Australia, Bostock identified 43 online forums that refer to ‘keto flu’. The team gathered personal experiences of 101 people who described ‘keto flu’ symptoms, to determine their severity and time course.

“We focused on social media because of its widespread use for discussion on health topics, which makes it practical to harness the experience of people who have tired the treatment in question,” ​said Bostock.

“In the present study, we responsibly and respectfully used public domain online forum posts and analysed their content to produce new insights into side-effects of the ketogenic diet.” ​ 

Flu-like symptoms reported by 44.5% of online users

Overall, personal experience of keto flu was reported by approximately one-third of the online forum users. Symptoms were typically reported within several days of commencing the diet – peaking within the first week and dwindling after four weeks.

In particular, researchers noted reports of headaches (24.7%), difficulty concentrating (10.9%), and gastrointestinal discomfort (10.9%) in the early stages of following a keto diet.

Additional symptoms reported by individual users were flu (44.5%), fatigue (17.82%), nausea (15.8%), dizziness (14.8%), decreased energy (9.9%), feeling faint (7.92%), heartbeat alterations (5.9%), sore throat (5.9%), decreased appetite (4.9%), shaking (4.9%), and body aches (3.9%).

Such findings suggest that the physiological and perhaps psychological changes associated with the ketogenic diet ‘result in the manifestation of an induction and adaptation related syndrome’, noted the authors.

However, it is not clear whether this should be understood as an ‘illness state’ produced by nutritional and perhaps immune imbalance, or is ‘indicative of an adaptive bodily process’ triggered by the diet.

"Taken together, such reports can bring an illness or side effects into focus and can complement clinical observations and questionnaire-based research,"​ noted Bostock.

"We see potential for research of this nature to inform all aspects of health care on a continuous basis."

Source:Frontiers in Nutrition
‘Consumer reports of “keto flu” associated with the ketogenic diet’
Published 13 March 2020
DOI: https://doi.org/10.3389/fnut.2020.00020​ 
Authors: Emmanuelle C. S. Bostock, Kenneth C. Kirkby, Bruce V. Taylor and Jason A. Hawrelak

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