What is Keto Flu

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If you’ve given the keto diet a try, you’re probably familiar with the term “keto flu.” It refers to the set of symptoms that many people experience when they first start following this low-carb lifestyle. There are no real medical reasons why your body will experience these changes, but they can be unpleasant at times. Fortunately, there are some things you can do to help ease those symptoms and make sure your body adjusts as quickly as possible.

What is Keto Flu?

The keto flu refers to a collection of temporary symptoms that may occur when your body adapts to the ketogenic diet. As you transition from a diet high in carbohydrates to one that is low in carbs and high in healthy fats, your body undergoes significant metabolic changes. During this transition, some individuals may experience flu-like symptoms, hence the term “keto flu.” It is important to note that the keto flu is not an actual viral or bacterial infection, but rather a natural response to dietary changes.

Symptoms of the Keto Flu

The symptoms of the keto flu can vary from person to person, but they typically resemble those experienced during a traditional flu or a mild case of dehydration. Here are some common symptoms you may encounter during this phase:

  1. Fatigue: Feeling tired and lacking energy is a prevalent symptom of the keto flu. Your body is adjusting to a new source of fuel, and this adaptation process can temporarily drain your energy levels.
  2. Headache: Many individuals report experiencing headaches or migraines during the keto flu. These headaches may be caused by the initial withdrawal from carbohydrates and the shift in electrolyte balance.
  3. Brain Fog: It’s not uncommon to experience temporary mental fog or difficulty concentrating while going through the keto flu. This can be attributed to the adjustments in brain metabolism as your body adapts to utilizing ketones for energy.
  4. Nausea and Dizziness: Some individuals may feel queasy or dizzy during the keto flu. This could be a result of electrolyte imbalances and dehydration, which are common when reducing carbohydrate intake.
  5. Digestive Issues: Changes in dietary patterns can lead to digestive discomfort such as constipation, diarrhea, or bloating. These symptoms usually subside as your body adapts to the new eating plan.
  6. Sleep Disturbances: It’s not uncommon to experience disruptions in sleep patterns during the keto flu. This can include difficulty falling asleep, frequent awakenings, or vivid dreams. These issues are typically temporary and tend to resolve as your body adjusts to ketosis.

Duration of the Keto Flu

The duration of the keto flu varies from person to person. Some individuals may experience symptoms for a few days, while others may find the transition phase lasts up to a week or more. The intensity and duration of the symptoms can depend on several factors, including your individual metabolic flexibility, previous dietary habits, and overall health.

Strategies to Alleviate the Keto Flu

While the keto flu can be uncomfortable, there are several strategies you can employ to alleviate the symptoms and ease the transition into ketosis. Here are some helpful tips:

  1. Stay Hydrated: Proper hydration is crucial during the ketogenic diet transition. Make sure to drink plenty of water and consider adding electrolytes to your regimen to maintain a healthy balance.
  2. Increase Healthy Fats: Gradually increase your intake of healthy fats, such as avocados, nuts, seeds, and olive oil. This will provide your body with the necessary fuel and support the transition into ketosis.
  3. Consume Adequate Electrolytes: As your body adapts to a lower carbohydrate intake, it is essential to replenish electrolytes, including sodium, potassium, and magnesium. You can obtain these from foods such as leafy greens, bone broth, and avocados. Alternatively, you can consider using electrolyte supplements to ensure you maintain proper electrolyte balance.
  4. Include Fiber-rich Foods: Incorporating fiber-rich foods into your diet can help alleviate digestive issues associated with the keto flu. Opt for low-carb vegetables like broccoli, cauliflower, and spinach, as well as chia seeds and flaxseeds.
  5. Manage Stress and Get Adequate Rest: Stress and lack of sleep can exacerbate the symptoms of the keto flu. Practice stress management techniques like meditation or yoga, and prioritize getting enough sleep to support your body during this transitional phase.
  6. Exercise Moderately: Engaging in regular, moderate exercise can help your body adapt to the ketogenic diet more smoothly. Aim for activities like walking, cycling, or strength training, but be mindful of your energy levels and listen to your body’s cues.
  7. Gradual Carbohydrate Reduction: If you find the symptoms of the keto flu too intense, you can try a more gradual reduction of carbohydrates instead of a sudden shift. This approach allows your body to adapt more gradually and may minimize the severity of the keto flu.

Remember, the keto flu is a temporary phase that typically resolves as your body becomes fat-adapted. It’s important to consult with a healthcare professional or a registered dietitian before making any significant dietary changes, especially if you have underlying health conditions or take medications.

What Causes Keto Flu?

The keto flu is a result of the body switching over to ketosis. This process can take anywhere from three days to two weeks, depending on how fast your body converts fat into energy and how much fiber you eat. Keto flu symptoms include fatigue, headaches, and brain fog (which may make it difficult for you to remember things).

It’s important not to confuse these symptoms with the flu—keto flu does not cause chills or runny noses; instead, it’s characterized by low energy levels accompanied by a feeling of discomfort or pain in the abdomen area.

When does Keto Flu Start?

But this process doesn’t happen overnight; instead, it takes place over several days or even weeks. And as your body adapts to this metabolic state, it also has to adapt to using something other than glucose for fuel. This is what many people refer to as “the switch.”

The good news is that once you get through the initial transition period and can maintain ketosis regularly (at least two times per day), your body will become more efficient at burning fat instead of sugar and continue improving its ability over time—and eventually stop producing excess insulin altogether!

Some signs your body is making this switch are associated with what’s known as the “keto flu.” But unlike real flu symptoms, this mostly affects your mood and energy levels. Most people report feeling drowsy or lethargic on their first few days of the keto diet while they adjust to these changes.

Once you’ve adapted to the shift in your body’s metabolism, you’ll notice a few extra symptoms. They may be associated with what’s known as the “keto flu.” But unlike real flu symptoms, this mostly affects your mood and energy levels. Most people report feeling drowsy or lethargic on their first few days of the keto diet while they adjust to these changes.

These symptoms typically subside after about a week of eating keto—but if they persist beyond three days, see a doctor immediately! You could have something more serious going on such as dehydration or electrolyte imbalance; it’s always better safe than sorry when it comes to health matters like this one!


So what can you do if you feel like you’re in the keto flu? There’s no need to panic. As we’ve discussed, this is a normal effect of changing your diet. Once your body gets into ketosis, it’ll stop experiencing these symptoms and start feeling better.


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