The Lamen
The keto flu is a sign of adaptation — showing that your body is switching over from carbs to fats as its primary source of energy. This transitory period, however, can cause some temporary flu-like symptoms.
Illustration: The Lamen
Benefits of the ketogenic diet start to set in only after a period of dizziness, headaches, and nausea — known as the “keto flu.” The condition describes a herd of symptoms that some people experience early into the keto diet.
Common symptoms of keto flu include:
These symptoms can often be confused with influenza or the flu. Typically occurring 2-3 days following the initiation of the ketogenic diet, the keto flu can last anywhere from a few days to several weeks.
A ketogenic diet maintains the body in a state of nutritional ketosis, characterized by the presence of acetone, acetoacetate, and beta-hydroxybutyrate molecules, collectively called ketone bodies — formed by the breakdown of fats.
Often a phase of adaptation, keto flu can be caused due to:
Symptoms of keto flu may cause many people to prematurely give up the ketogenic diet, or even be misdiagnosed. Your body builds more mitochondria and ketone-producing enzymes during this transitory phase. Meanwhile, your gut adapts to digest fats more efficiently.
Staying hydrated, supplementing with electrolytes, moderate-intensity exercise, and reducing caffeine intake are all known to help with the symptoms of keto flu.
The Keto Diet podcast host and author of the best-selling book of the same name, Leanne Vogel, highlights some common mistakes that may cause these side effects:
Sticking to the diet for long enough typically makes the undesirable side effects go away. However, if your symptoms persist, you might consider switching to the Mediterranean or DASH diet — each supported by evidence of prolonging life and reducing the risk of chronic health conditions.