The ketogenic diet has gained popularity as a method for weight loss and potential health improvements. However, some individuals experience unpleasant side effects when starting this diet, often referred to as the "keto flu" or "carb flu." This article delves into what the keto flu is, its causes, and strategies to alleviate its symptoms.
Understanding the Keto Flu
"Keto flu" is a term used to describe common side effects experienced during the initial stages of a ketogenic diet. These symptoms arise as the body adapts to a new diet that is very low in carbohydrates, high in fat, and moderate in protein. The keto flu is not actually the flu, and it is not caused by being in a state of nutritional ketosis. Rather, the ”flu-like” symptoms that some individuals experience when starting the ketogenic diet is due to the body’s response to carb restriction.
When you begin to restrict carbs from the diet, the kidneys (the body’s filtration system) switch from retaining sodium (aka salt) to rapidly excreting it, along with excess water in the body. During the clearance of extra sodium and water from the body, many people experience rapid weight loss. While it may be exciting to see the scale move in a downward direction, know that this is not true weight loss from fat, but instead from the water loss. Therefore, it is important that you replace some of the sodium and water that you are excreting because if these are not replaced, it is likely that you will experience symptoms of keto flu.
What Causes Keto Flu?
The ketogenic diet forces the body to undergo significant changes, including withdrawal from sugar and carbohydrates. Transitioning into ketosis, a metabolic state where ketone bodies are produced for fuel instead of glucose, can initially cause side effects as the body adjusts. This is because the body has likely been primarily using glucose for fuel throughout a person's life.
Reducing carb intake forces your body to burn ketones for energy instead of glucose. Ketones are byproducts of fat breakdown and become the primary fuel source when following a ketogenic diet. Switching to a very low carb diet is a major change, and your body may need time to adapt to this new way of eating.
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Keto Flu Symptoms
Signs of the keto flu may appear within the first few days of reducing carb intake. Symptoms can vary in severity from person to person. While some individuals may transition to a ketogenic diet without any side effects, others report symptoms such as:
- Nausea
- Vomiting
- Constipation
- Diarrhea
- Headache
- Irritability
- Weakness
- Muscle cramps
- Dizziness
- Brain fog
- Stomach or intestinal pain
- Muscle soreness
- Difficulty sleeping
- Food cravingsFatigue-especially around exerciseLightheadedness
These symptoms typically last a few days or, in rare cases, up to several weeks.
Strategies to Prevent and Minimize Keto Flu Symptoms
Fortunately, there are several ways to reduce keto flu symptoms and help your body adapt to the transition period.
1. Adopt Alkaline Diet Principles and Focus on Nutrient Density
The ultimate goal of following the keto diet should be to feel better and get healthier. In order to do this, you need to adopt alkaline diet principles, which help to reduce inflammation, restore your nutrient stores and balance your body’s pH level.
- Fresh vegetables: Emphasize green vegetables and include raw foods to boost enzyme intake.
- Alkaline water: Opt for water with a pH of 9 to 11.
- Green drinks: Incorporate green drinks into your diet.
- Limit or avoid caffeine: Reduce or eliminate caffeine consumption.
- Avoid inflammatory foods: Stay away from processed foods filled with additives and synthetic ingredients. Limit unhealthy "low-carb foods" that are difficult to digest.
2. Ensure Adequate Fat Intake
Staying in ketosis requires obtaining approximately 80 percent of your daily calories from fat sources. Healthy keto-friendly fats include:
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- Coconut oil
- Real olive oil
- MCT oil
- Grass-fed butter
- Ghee
- Fattier cuts of meat
If you deviate significantly from these guidelines, you may not enter or stay in ketosis, leading to symptoms like low energy and brain fog. Track your macronutrient ratio to make necessary adjustments. Consume more fat if you feel hungry or weak, and avoid being in a chronic calorie deficit.
3. Stay Hydrated
Dehydration can worsen keto flu symptoms. Drink a glass of water every 1-2 hours and consume hydrating foods like vegetables, bone broth smoothies, or green juices. Staying hydrated helps with headaches and boosts your energy levels. One way to help yourself remember to drink water is to set a reminder on your phone, or always keep a full glass of water within reach. Most people don’t know how much water to drink every day, but it’s easy to determine - just take your current body weight and divide it by two. That’ll give you the minimum ounces of water to drink every day.
4. Replace Electrolytes
Electrolytes like magnesium, potassium, and sodium can be lost at a higher rate during ketosis due to increased urination and the kidneys flushing out sodium. To prevent muscle aches and other side effects, consider:
- Taking a magnesium supplement before bed.
- Increasing salt intake (e.g., adding bouillon cubes to water to make a quick broth).
An extremely low carb keto diet means you end up cutting out some of the richest natural resources of electrolytes, such as starchy fruits and vegetables.Salting food to taste and including potassium-rich, keto-friendly foods like green leafy vegetables and avocados is an excellent way to ensure a healthy balance of electrolytes. These foods are also high in magnesium, which may help reduce muscle cramps, sleep issues, and headaches.
5. Increase Fiber Intake
Include keto-friendly fiber foods in your diet, especially vegetables, to prevent constipation and diarrhea. Vegetables add volume to meals, provide essential vitamins and minerals, and are full of antioxidants and fiber. Seeds and nuts (almonds, walnuts, cashews, pistachios, and brazil nuts in moderation) are also good sources of fiber and trace minerals. Almond meal/almond flour can be used in place of regular flour.
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6. Incorporate B Vitamins
Consume 1-2 tablespoons of nutritional yeast daily to easily increase your B vitamin intake.
7. Adjust Exercise Routine
Reduce your exercise load initially until you feel better. Stick with lighter forms of exercise like walking outdoors, yoga, or light cycling during the beginning phase of the keto diet. Hold off on high-intensity exercise until you no longer feel fatigued, weak, and dizzy.
8. Get Adequate Sleep
Fatigue and irritability are common complaints during the adaptation period. Lack of sleep can worsen keto flu symptoms. Improve sleep quality by:
- Reducing caffeine intake, especially in the afternoon and evening.
- Creating a dark sleep environment by eliminating ambient light from electronic devices.
- Taking a relaxing bath with Epsom salt or lavender essential oil.
- Waking up at the same time every day to normalize sleep patterns.If you’re having a hard time falling asleep or sleeping through the night, try taking an Epsom salt bath, as it will help soothe and relax your muscles as well as improve electrolyte absorption. You can also add on a keto-friendly herbal tea with a blend of herbs that calm your nervous system to help promote a deeper sleep.
9. Avoid Strenuous Exercise
While exercise is important for staying healthy, strenuous exercise should be avoided when experiencing keto-flu symptoms. Fatigue, muscle cramps, and stomach discomfort are common in the first week of following a ketogenic diet, so it may be a good idea to give your body a rest.
Activities like intense biking, running, weightlifting, and strenuous workouts may have to be put on the back burner while your system adapts to new fuel sources. While these types of exercise should be avoided if you are experiencing the keto flu, light activities like walking, yoga, or leisurely biking may improve symptoms.
10. Gradually Reduce Carbs
Transitioning to a very low carb diet can cause you to crave foods that are restricted on the ketogenic diet, such as cookies, bread, pasta, and bagels. Those who are having trouble adapting to the ketogenic diet may have to eliminate carbohydrates gradually rather than all at once. Slowly cutting back on carbs while increasing fat and protein in your diet may help make the transition smoother and decrease keto-flu symptoms.
11. Ease into the Diet
When making harsh diet changes, it’s always helpful to ease into it. The best approach would be to start with a typical low-carb diet and give your body time to adjust.
12. Ensure Adequate Calorie Intake
When on the keto diet, intake of healthy fats is crucial, as low calories can lead to keto flu symptoms. Do not reduce your calorie intake too much, and try not to go low-carb AND low-fat. Ramping up your fat consumption can help speed up the transition of burning fat instead of glucose for fuel.
13. Increase Salt Intake
The easiest way to minimize/avoid keto flu is to increase your salt intake by 1-2 grams/day-rest assured, while you are in nutritional ketosis you will not store this extra sodium in the body. An easy way to increase your salt intake is by drinking 1-2 cups of bouillon a day because each cube contains about 1 gram of sodium. Although drinking bouillon or broth might sound a little strange, it can actually be quite delicious. If you add a little butter and/or heavy cream to it you can create a savory ‘tea’ that is also a great source of fat, salt, and additional water! Even better, make your own ‘bone broth’ from leftover roast chicken, beef bones, or ox tails. It can be made in batches of 8-16 cups at a time and stored in the fridge or frozen for later use.
Factors Influencing Keto Flu Severity
People adapt to ketogenic diets differently. While some may experience weeks of keto-flu symptoms, others may adjust to the new diet with no adverse side effects. The symptoms people experience are tied to how their bodies adjust to a new fuel source. Those who typically consume lots of carbs, especially refined carbs like pasta, sugary cereal, and soda, may have a more difficult time when beginning the ketogenic diet.
The reason some people adapt to ketogenic diets easier than others is unknown, but genetics, electrolyte loss, dehydration, and carbohydrate withdrawal are believed to be the driving forces behind the keto flu.
Duration of Keto Flu Symptoms
The uncomfortable symptoms of the keto flu are usually temporary. For some people, symptoms resolve after only a few days. However, others may have a more difficult time adapting to this high fat, low carb diet. For these individuals, symptoms may last up to a month. Typically, these symptoms will gradually decrease as your body gets used to converting ketones into energy.
When to Seek Medical Advice
While keto-flu symptoms are commonly reported by those shifting to a ketogenic diet, if you are feeling particularly unwell and experiencing symptoms like fever, prolonged diarrhea, or vomiting, it’s best to contact your doctor to rule out other causes.
Contraindications
Although the ketogenic diet may be helpful for many people, it’s not suitable for everyone. For example, the ketogenic diet may not be appropriate for pregnant or nursing people, children, and teens unless it’s being used therapeutically under medical supervision. Also, those with diabetes, kidney disease, liver disease, or pancreatic conditions who are interested in following a ketogenic meal plan should consult their doctor to determine if this diet is safe and suitable for their specific needs. Lastly, this diet may not be appropriate for individuals who are hypersensitive to dietary cholesterol, who account for around one-quarter of the world’s population.