What Is Keto Flu? Symptoms, Causes, and How To Manage It

What Is Keto Flu? Symptoms, Causes, and How To Manage It

Have you recently started a ketogenic diet and begun experiencing flu-like symptoms? You may be experiencing what is known as the "keto flu." 

This strange (but common) side effect can occur in the first week of a low-carb, high-fat diet, leaving you tired, weak, and dizzy. While it's not the flu, this condition can make you feel unwell and may discourage new keto dieters from sticking to their diet plan.

With the right information and strategies, you can successfully manage keto flu symptoms and stick to your weight loss goals. Together, we’ll discuss everything you need to know about keto flu, including its symptoms, causes, and effective management tips.

What Is the Keto Flu?

Starting a new diet can be exciting, but it can come with challenges like the keto flu. This is a collection of symptoms people may experience in the first week of a low-carb, high-fat ketogenic diet.

In a standard diet, carbohydrates are the primary fuel source for the body, providing glucose for energy. While on a low-carb diet, the body transitions into a metabolic state of ketosis, which means it burns fat for fuel instead of carbohydrates. 

Ketosis occurs when carbohydrate intake is restricted, forcing the body to use stored fat as its energy source, leading to fat-burning and weight loss.

This change in energy source can tax the body and may come with side effects, such as flu-like symptoms. The keto flu is not an actual flu, but it can certainly make you feel like you have one!

But don't worry! It's a natural part of the transition into a state of ketosis, usually lasting only a few days to a week. Luckily, it is possible to manage the symptoms of the keto flu and make the transition into ketosis more comfortable.

What Causes the Keto Flu?

Now that we know what the keto flu is, it's a good idea to understand what causes it. When you start a low-carb, high-fat ketogenic diet, your body undergoes significant changes in its metabolic state.

During the initial phase of a keto diet, the body experiences a rapid reduction in carb intake, leading to a significant decrease in glycogen stores. Glycogen is the body's preferred fuel source, and when depleted, the body must adapt to using a different energy source.

Another factor that contributes to the keto flu is an electrolyte imbalance. As the body starts to burn fat for fuel, it produces ketones as byproducts of the fat-burning process. These ketones cause the kidneys to excrete more electrolytes, such as potassium and sodium, which can cause imbalances in these crucial minerals.

Additionally, the high-fat, low-carbohydrate nature of the keto diet can cause sugar cravings and other symptoms of withdrawal from a high-carbohydrate diet, which some people refer to as "carb flu."

What Are the Symptoms of the Keto Flu?

Brain fog is a common symptom of the keto flu, making it challenging to concentrate and remember things. You may also experience muscle cramps and other muscular pains due to electrolyte imbalances.

Constipation is another symptom that may arise due to a change in your diet's fiber content. Lastly, you may experience fluctuations in your energy levels, ranging from feelings of high energy to periods of fatigue. Fatigue is also a common symptom as the body adjusts to using fat instead of glucose as its primary fuel source.

If you experience severe or prolonged symptoms, consult your healthcare provider.

How Can You Manage Symptoms of Keto Flu?

When starting a ketogenic diet, a balanced electrolyte intake is essential to prevent the onset of the dreaded keto flu. Luckily, there are some keto flu remedies that can help alleviate symptoms. 

By taking a few simple steps to prepare, you can minimize how long keto flu lasts so that you can stay on track toward achieving your goals.

Drink Lots of Electrolytes

Electrolytes are essential minerals that help vital processes such as regulating fluid balance and nerve and muscle function. When following a ketogenic diet, your body loses a lot of electrolytes, mainly due to reduced insulin levels and fluid output. If you're not careful, this can lead to dehydration, exacerbating the keto flu symptoms.

One of the most effective ways to manage the keto flu symptoms is by ensuring that you're staying adequately hydrated and getting enough electrolytes. 

To prevent this, you may want to try drinking plenty of water throughout the day and taking electrolyte supplements that contain essential minerals like magnesium and potassium. Don't drink a lot of water without supplementing it with electrolytes ­–– plain water may just flush more electrolytes out of your body.

Drinking bone broth can also help keep you hydrated and replenish electrolytes, helping to manage keto flu symptoms. Dr. Kellyann's Bone Broth Liquids and Powdered Bone Broths are excellent options, as they contain sodium and potassium, which are essential for maintaining hydration and electrolyte balance. Plus, they’re a delicious way to start and end your day!

Dr. Kellyann's Collagen Cocoa is not only a delicious way to satisfy your sweet tooth, but it's also a source of calcium. Calcium is an essential nutrient and electrolyte critical to bone health, muscle function, and nerve transmission.

By getting enough water and keeping up with your electrolyte intake, you can reduce the severity of the keto flu and help it pass more quickly. 

Increase Your Fat Intake

Adding plenty of healthy fats can help you feel satisfied and energized while preventing cravings for carbs and sugar. Dr. Kellyann's keto-friendly collection of products offers easy ways to add fat and other essential nutrients to your meal plan.

One of the easiest ways to include fats in your diet is by incorporating them into smoothies. For instance, avocados are excellent sources of fiber, healthy fats, and essential nutrients like potassium, magnesium, and vitamins C and E. 

Toss an avocado in with Dr. Kellyann's Collagen Smoothies to make a delicious, high-fat breakfast or snack.

Another excellent addition to your smoothies is coconut oil or MCT oil. These are great sources of easily digestible fatty acids and can also help support your energy levels.

Fat bombs are also popular high-fat snacks among those following a ketogenic diet — and for a good reason. They are an easy way to increase your fat intake and satisfy your hunger while managing your carb intake. Dr. Kellyann's Coconut Mocha Collagen Bombs are an excellent example of a delicious and healthy fat bomb recipe that can help you meet your macronutrient goals.

Take a Rest Day

Taking a rest day can also be helpful when managing the symptoms of keto flu. The body needs time to adjust to the new fuel source, so rest can help it transition efficiently and support overall wellness.

It's important to note that rest doesn't necessarily mean being sedentary all day. Light activity, such as gentle stretching or a walk around the neighborhood, can be helpful. However, avoiding intense workouts during the first week of starting a ketogenic diet is generally best.

If you're used to working out regularly, taking a rest day may feel counterproductive. Listen to your body and give it the rest it needs to adjust to the new diet.

Start Off Slow

When starting the keto diet, take it slow and don't jump into it full force. The body needs time to adjust to the new diet, and rushing into it can lead to keto flu symptoms. Here are some tips to help you start slow:

  1. Gradually reduce your carb intake: Start by slowly lowering your carb intake for a few days or weeks. Going slow can allow your body to gradually adjust to the new fuel source.
  2. Gradually increase your fat intake: Add healthy fats to your diet as you reduce your carb intake. This can help your body get used to the new fuel source and prevent the keto flu.
  3. Start with a moderate exercise routine: Don't jump into an intense exercise routine right away. Start with a moderate exercise routine, such as a daily walk or light yoga, and gradually increase the intensity.

Starting slow can not only help prevent the keto flu but can also help ensure long-term success on the keto diet.

The Bottom Line

The keto flu is a temporary side effect of the body adapting to a new fuel source, and it typically subsides within a week or two. Staying hydrated, increasing electrolyte intake, gradually increasing fat intake, taking rest days, and starting slow can help you manage the keto flu or avoid it entirely.

By being prepared and taking these steps, you can minimize the impact of the keto flu and make your transition to the keto diet as smooth as possible. Trust your instincts and seek medical advice from your healthcare provider if you're experiencing severe symptoms or have any concerns.

If you’re ready to start your keto journey, let Dr. Kellyann help. With a vast library of keto recipes and a wide selection of easy, keto-friendly products, we can help you satisfy your cravings while still supporting your health.


Consumer Reports of "Keto Flu" Associated With the Ketogenic Diet | National Library of Medicine

What is keto flu? | Harvard Health

Are you over-hydrated? | Gundersen Health System