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Keto Flu 101: Everything You Need To Know

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In Keto Flu 101 my goal is to answer the questions I get asked on a daily basis about the Keto Flu. Many people who are interested in going into ketosis are afraid that they will get the keto flu and are looking for ways to avoid getting it all together. While every person’s experience is different, knowledge is power, so prepare to arm yourself with as much information about the keto flu as possible before you start the diet, so you know what to expect.

Keto Flu 101 - Everything You Need To Know About Keto Flu

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Already started Keto? Don’t worry; this post will still give you the tools you need to prepare yourself as well. Look, this is the rest of your life we are talking about.  As my favorite author, C.S. Lewis said “Hardship often prepares an ordinary person for an extraordinary destiny.” and that is true even in the case of the keto flu!

Hardship often prepares an ordinary person for an extraordinary destiny

Keto Flu 101: Everything You Need To Know 

The “keto flu” is what we commonly call carbohydrate withdrawal symptoms. These symptoms usually occur in people who start a low carb diet that alters their hormones and causes and electrolyte imbalances. Don’t let this alarm you; this is a GREAT thing. In other words, it describes a cycle in the body adapting to a newly started low carb diet.  Think about the keyword here, which is withdrawal. The same way an addict withdrawal from any drug. Your body is so used to living off of carbs that both your body and your mind think you need these to survive.

On most diets you’ve tried in the past, your mind was probably much harder to fight than your body. Maybe you’ve never been on a diet that caused you to go through any form of withdrawal, and that’s where you’ll find the greatest source of power when it comes to Keto! With Keto, once your body goes through withdrawal, you’ll find that the temptations you used to face (thoughts of wanting to cheat, cravings, starving) those things will not be a problem for you.

This might not make any sense to you right now, but bear with me because this is about to be the most exciting thing you’ve done for your body in a long time!

Keto Flu Symptoms Keto Size Me

Keto Flu Symptoms:

No two people experience the keto flu, in the same way, so the symptoms can range from nothing to mild to a full-blown flu-like condition, and include

  • Lightheadedness
  • Nausea
  • Fatigue
  • Mental fog
  • Cramps
  • Headaches
  • Diarrhea
  • In some extreme cases, high blood pressure and arrhythmia

How Long Does Keto Flu Last?

The duration of keto flu varies for each person. While some may have slight and even unnoticeable symptoms for a day or two, others might have an over the top symptom for a week or more; it depends on how quickly your body adapts to a reduction in carbs. My recommendation if you are really worried about the keto flu is to start slowly weaning yourself off carbs before starting keto. My entire family has joined me on keto, then gone off for a period (over summer vacation), then started again. They experienced the best results with the keto flu when they started limiting carbs before going full keto; this gave their bodies time to adapt before rapidly entering keto. I believe this is especially important for children. I don’t like seeing my children go through the keto flu. 🙁

Once keto flu is over, you can expect a huge surge in energy levels, and once that sugar habit is fully kicked, you will likely feel better than ever.

My dad is probably the best example I have seen of this. He went from being a full-on couch potato to a working machine. He was off the couch doing projects around the house that my mom had been asking him to do for years! We couldn’t get him to sit still. His energy level was through the roof, and he even looked younger. It is amazing what a difference eating the right foods can make. Don’t take my word for it. Start the keto diet and see for yourself!

Note: Being patient as your body adapts is key, and know that it will pass, and if it does not you should seek the attention of a qualified medical professional. For most people any symptoms that occur end within two weeks’ time.

Keto Flu: A Misunderstood Condition

People who experience keto flu after going on a low carb diet are sometimes forced to believe that they are suffering due to the diet they are on, and carbs are good for the health after all DON’T buy into this carb lovers LIE!

This only proves how dependent you have been on carbs, as your body is trying to survive without carbs and sugary substances.

In truth, carb intake, and especially refined carbs that come from processed food, sugar, sugary foods, and drinks is at epidemic levels, and carb addiction is rampant in the United States and other parts of the world.

I’m not blaming YOU; those carbs are everywhere, congratulate yourself on making changes for the better with a low carb diet! I’m applauding you right now! 🙂

How To Reduce The Effects of the Keto Flu

Keto flu can be a total pain in the butt and everywhere else, it is also sometimes a necessary evil. However, there are some things that can be done to reduce the symptoms if they appear.

Electrolytes: Lack of electrolytes in the body is one of the leading causes of keto flu. Electrolytes are the minerals found in the body, and they affect its water content, acidity, of the blood and functionality of the muscles.

Low carb diets feature lower insulin levels that can signal the kidneys to discard excess water, making you drink more, and this results in flushing out electrolytes, where sodium, potassium and magnesium deficiencies can occur. You will have to replenish them by using supplements and with food.

Up The Salt:  Normally, the average diet is overloaded with salt, but a ketogenic diet eliminates refined and processed food and focuses on eating whole real food, so when you start keto you will naturally reduce salt intake, which reduces water retention. Since a low carb diet is naturally diuretic, there is no need to worry about water retention so feel free to put the salt back on the table!

5 grams of salt daily is ideal for keto flu and to replenish electrolytes; you can also get it from drinking 2 cups of broth or adding soy sauce and other sauces that have potassium to your meals. I love chicken broth, and when I first started keto, I would usually drink a bowl a day.

Bone broth works well, and only requires the simmering of chicken, beef, lamb or any meat bones in water for about a day, or even canned broth or stocks from the store works well too, just make sure to read the labels for added ingredients or preservatives that you do not need. Drippings from cooked meat have a high concentration of potassium, so use them to make sauces.

Magnesium Take 300mg a day to help with keto flu. I continued magnesium and still take it today. I will write more about this in a separate post.

Have other questions about the Keto Diet? Check out Keto 101

Please contact a doctor if the symptoms become too severe to handle alone.

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Saturday 2nd of September 2017

Can you experience symptoms within the 1st 24hrs?


Friday 1st of December 2017

I'm on day one of keto and I already feel foggy and have a headache. Hoping it passes quickly!


Friday 8th of September 2017

If you usually eat a ton of carbs it would be possible. Similar to people who take in lots of caffeine and have a headache within 24 hours of abstaining.


Friday 25th of August 2017

It's interesting how everyone is different- I went five weeks and didn't experience any of the "keto flu" symptoms until this week, week 5. Over the past 5 weeks, I've kept my daily carbs under 20, my fat intake at approximately 78% and my protein at about 21%. All of the sudden during week 5, I'm fatigued, my muscles are sore and tight, and I've experienced muscle cramps. Adding sodium via beef broth has really helped. I'm also supplementing with magnesium & potassium. My appetite is also through the roof and I've gained back 5 of the 14 lbs (literally overnight) I've lost despite the fact that I've followed my plan 100%. I know this is only temporary and I'll be back to losing once my body deals with all the newness I'm throwing its way.


Monday 7th of August 2017

Can water retention be a sign of keto flu? I've been trying to do a low carb/ keto diet for 3 weeks and the past few days I have been holding a lot of water. I don't have a menstrual cycle so I know that isn't the reason and I've been drinking lots of water. I don't know if I should stop the diet or not?


Wednesday 29th of March 2017

I have successfully kept my net carbs below 25 g for most of an 8 day period; some of those days were right at 20g. I felt great... energy in the afternoon when I didn't usually have any.

On day 9, however, I am having symptoms of the "flu" - headache, fatigue, mental fog, nausea in the morning... what gives? I thought if I were to have the flu, it would be right away. Is this normal?

I am on day 10 right now, and don't plan to give up. I am counting my macro's using MyFitnessPal - eat whole foods and keeping my water and electrolytes up.

I guess my main question is, can the flu hit after you've been on this lifestyle of eating after 8 days?


Tuesday 5th of December 2017

I was feeling great until day 9 and 10... low mood, tired, weak.


Tuesday 11th of July 2017

I have the exact same thing happening, been on about ten days and feeling great then just wham, get hit with massive fatigue. Did you get past it?




Thursday 22nd of June 2017

Exactly my experience. No symptoms initially then on day 6 I was totally zapped of energy. I couldn't even raise my arms to wash my hair in the shower! Then on day 8, I got the headaches, mental fog...still no energy. I am on day 9 now. Still no energy, still with the headaches and mental fog. I am hoping I'm hoping it's my bodies last ditch attempt into tricking me to eat carbs so I am sticking it out. I hope it passes soon as feel dreadful..


Tuesday 13th of June 2017

You may not have entered, or should i say, transitioned into Ketosis as soon as you thought. Possibly a misjudgement on carb intake etc. Im not sure. But thats my guess. Did you get through it? how are you feeling now?


Monday 22nd of May 2017

That is interesting. I am experiencing the same effects myself. I am on my ninth day and I feel like the worst flu in the world is in my bones. It is really scary for me to think that my mind and my body have become so reliant on carbs to this point. If I am detoxing, I feel like a real heroin addict. This sucks! Any ideas on how I can relieve some of these symptoms? I pray to God that the payoff is worth it, because right now it doesn't feel worth it. How long did your symptoms last? Thanks for posting. I really appreciate it.

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