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 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.
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.