The “keto flu” can be unnerving if you don’t understand it.
Without prior knowledge, the symptoms can lead a new keto dieter to believe the diet isn’t working for them. Thankfully, that’s not the case at all!
The keto flu is a natural reaction to entering ketosis, it’s very temporary, and there are ways to remedy it. We’ve included all the details you need to know about the keto flu and what to do if you experience it.
In this article, you’ll learn:
- What is the keto flu?
- Symptoms of the keto flu
- Causes of the keto flu
- How to get rid of the keto flu
- How to prevent the keto flu
- Takeaway: How to remedy the keto flu now
Your body burns carbohydrates (glucose) for energy by default.
But when your carb intake is drastically reduced, like on the ketogenic diet, your body is depleted of stored glucose and instead turns to burning fatty acids for energy. This is the metabolic process of ketosis.
The keto flu is a natural reaction to our bodies are entering ketosis and switching to a state of glucose-burning to fat-burning.
Your body’s response to entering ketosis can often mimic symptoms of the flu, thus the name “keto flu.”
Most people experience the keto flu when they first start keto. Here are some of the most frequently reported manifestations of it:
- Stomach aches or pains
- Brain fog
- Dizziness or confusion
- Diarrhea or constipation
- Muscle cramping or soreness
- Lack of concentration or focus
- Trouble falling or staying asleep
- Sugar cravings
- Heart palpitations
Keto flu symptoms usually occur within the first day or two of starting a ketogenic diet, and the severity and length of symptoms vary per person. Some people may have no symptoms at all, while others could experience several for up to a week or two.
Either way, the symptoms shouldn’t last more than a couple weeks and should go away once your body is adapted to burning fat for fuel.
The keto flu is essentially the result of three things:
- Becoming fat-adapted or keto-adapted.
- Electrolyte loss and dehydration.
- Withdrawal from carbohydrates and sugary foods.
- Lack of Micronutrients
Our bodies have two primary sources of energy:
- Glycolysis: converting glucose into energy
- Beta-oxidation: converting fat into energy
Keto-adaptation means getting the body used to the process of beta-oxidation. This is easier for some bodies than others.
Metabolic flexibility refers to how well a person can adapt to using a different fuel source: switching from burning glucose to burning fats.
Those with less metabolic flexibility are more likely to experience keto flu symptoms as their body adjusts to using fat for energy.
Genetics also play a part. Some people are simply better able to handle the energy switch.
#2: Electrolyte Imbalance
When you make the radical switch of cutting out the high-carb processed foods you find in The Standard American Diet (SAD), your body will rapidly lose water.
This is because all the glycogen (stored glucose) you’ve been accumulating on a high carb diet is bound to water in your body (each gram of glycogen is stored with 2–3 g of water).
When you go keto, your cells use up all that glycogen, and the water holding it has to be flushed out.
All this water flushing out of your body will carry electrolytes with it, which causes dehydration and electrolyte imbalances.
This can cause flu-like symptoms until everything becomes balanced again.
#3: Carbohydrate Withdrawal
Some research has shown sugar affects the brain in a way similar to heroin or cocaine[*]. It’s pleasurable, and we get a nice shot of the “feel good” hormone, dopamine, when eating sugar.
Plus, the addictive nature of these foods doesn’t help[*].
When sugar is drastically reduced from starting a keto diet, we can experience withdrawal effects like mood swings, irritability, cravings for sugar, and other symptoms of the keto flu.
Someone who has come from eating a diet full of processed and refined carbs and sugars is more likely to also experience these withdrawal-like symptoms and have more trouble adapting to fat burning.
Now that we’ve covered the main reasons behind the keto flu, let’s talk about how to alleviate these issues.
#4: Lack of Micronutrients
One of the easiest traps ketogenic dieters can fall into is not getting enough micronutrients from their diet.
When you cut out vegetables, fruits, and grains, you need to eat adequate amounts of keto-friendly foods to get the micronutrients you were getting from those foods.
For example, if you stop eating carbs and start eating primarily eggs and cheese to stay keto, you’re at risk of creating nutrient deficiencies.
You need to eat a wide variety of nutrient-rich keto foods (such as organ meats) to make sure you stay healthy in your keto transition.
It’s also important to avoid foods on your keto diet that will make you unhealthy.
Supplementing with micronutrients can also help.
Although the keto flu is temporary, there are things you can do to reduce or even eliminate symptoms during the transition into ketosis.
If you suspect you’ve been hit with the keto flu already and it’s too late to prevent it, here’s what you can do to get rid of it:
#1: Stay Hydrated
The water loss that occurs at the beginning of a ketogenic diet needs to be replenished.
Make sure you’re drinking plenty of water throughout the day to help reduce symptoms like headaches, fatigue, or nausea that are often caused by dehydration.
- Keep water near you to drink regularly throughout the day.
- Always drink when you feel thirsty.
- Often thirst is a sign of dehydration already, so try to get ahead of it.
#2: Replenish Electrolytes
As mentioned above, electrolyte imbalances can cause keto flu symptoms. Here are some of the best ways to mitigate this:
- Increase your salt intake. This will help counteract the water loss that happens when starting a keto diet and replenish sodium.Get your sodium from Himalayan Pink Sea Salt instead of regular table salt.
- Supplement with magnesium.
- Eat keto foods high in potassium like leafy green veggies, salmon, nuts, avocados, or mushrooms.
- Eat keto foods high in calcium like leafy greens, sardines and salmon.
- Drink bone broth. Bone broth is not only incredible for your skin, but it provides electrolytes like sodium and potassium while also being hydrating.
- Take an electrolyte supplement. If you need instant relief, taking an electrolyte supplement will help replenish yours faster than foods can. See our Vitamin and Mineral Supplement guide for more.
Exercise performance may temporarily suffer while your body is adapting to higher fat and low carb intake.
At the same time, getting light exercise 2-3 times per week can help make your body more efficient at switching between carbs and fats for energy (also known as metabolic flexibility)[*], which helps to decrease keto flu symptoms more quickly.
#4: Increase Fats
Your body is no longer getting its energy from carbohydrates and sugars, so it needs plenty of fat for fuel. Make sure the calories from carbs are replaced by eating plenty of keto-friendly fats.
Supplement with MCT oil powder to help further increase ketone levels for fuel.
If the keto flu is persisting longer than a week, re-evaluate your macros. You might still be eating too many carbs and not enough healthy fats.
Sometimes, people think they’re transitioning into ketosis when in reality hidden carbs can be holding them back.
#5: Take Exogenous Ketones
Remember that one of the reasons you may have the keto flu is your body is trying to become keto-adapted — which means creating and using ketones for energy.
Exogenous ketones are ketone salts you can ingest.
They provide your body with additional ketones to help it become more fat-adapted and enter ketosis more quickly. This can be really helpful in preventing or even eliminating keto flu symptoms.
How To Prevent The Keto Flu: 3 Steps
If you’re just starting the keto diet and want to prevent the keto flu altogether, it can be easily avoided if you follow these steps:
#1: Follow A Nutritious Ketogenic Diet
One of the main reasons beginner keto-ers start to feel unwell on keto is a lack of proper micronutrients in their diet.
The ketogenic diet is not just about macronutrients. You could technically hit your macros by eating nothing but cottage cheese, but that would lead to nutrient deficiencies and, eventually, the keto flu.
The key to transitioning to keto with few to no side effects is starting with a healthy ketogenic diet that covers all your nutritional needs.
You can follow this 7-day meal plan to get used to eating keto.
It’s also important you avoid unhealthy foods that raise your blood sugar, insulin levels, and kick you out of ketosis.
#2: Get Plenty of Sleep
Getting at least seven hours of sleep a night is important for anyone, and even more so for the keto dieter.
Your metabolism is getting used to switching fuel sources, so getting plenty of sleep can help reduce stress and fatigue.
If you struggle to get enough sleep per night, try incorporating a power nap or two into your day.
#3: Take Adequate Supplements
The easiest way to avoid side effects when you first start keto is to take the right supplements from the start.
Your keto diet should be based on healthy whole foods, but supplements can help fill in any nutritional gaps and make your life easier.
Here are the supplements you should take for different goals:
- Enter ketosis faster: Exogenous Ketone Base
- Balance electrolytes: Electrolyte supplement
- Get more micronutrients: Micronutrient Greens supplement
- Support ketone production: MCT Oil Powder
Takeaway: How To Get Rid Of The Keto Flu Now
The ketogenic diet is a great tool for improving your health,weight loss and feeling your best, but the keto flu can get in your way if you don’t know how to get over it.
If you already fell victim to this common hurdle, do this right now:
- Drink more water
- Take electrolytes
- Drink bone broth
- Increase your intake of high-quality fats
- Do light exercise if you can
- Take exogenous ketones to enter ketosis
If you haven’t gotten the keto flu and want to avoid it all together, prioritize this:
- Make sure you’re eating a healthy ketogenic diet
- Avoid foods that will kick you out of ketosis
- Rest enough as your body adapts to this metabolic change
- Take supplements strategically to support your keto diet and avoid the keto flu
Be Patient and Take Care of Yourself
Use the healthy tips above to help reduce symptoms and possibly even avoid the keto flu all together. Also keep in mind that the keto flu induction phase is just the beginning, and if you experience it, symptoms will subside — just give them time.
Once the hard part is over, you’ll be reaping the benefits of keto and thanking yourself for staying strong.