"What is the Keto Flu?" + 7 easy cures!

the keto flu

“Wait why am I doing this diet again?

All that talk about unlimited energy and mental focus… what a bunch of B.S.! I just feel exhausted, dizzy, and irritable. Ugh I’m gonna go lay down.”

Ever felt like that during your first week on keto? If so, it wasn’t all in your head. It was the keto flu. And it’s a big challenge for people starting out on the diet.

But the good news.. It’s temporary – we’re talking only a week for most people – and can be cured with a few easy steps. Today you’ll learn how to conquer the Keto Flu with 7 simple cures.

What is the Keto Flu?

what is the keto flu

The Keto Flu is your body’s response to switching from running off glucose to fueling with ketones. Glucose comes from carbs. Ketones come from fat.

Glucose is your body’s preferred fuel – remember you’ve spent your entire life burning these sugars to keep going. Keto is a shock to the system. And it’s normal to feel a bit funky during the transition.

Keto flu symptoms are a lot like what drug addicts experience from withdrawal. It no coincidence – studies have shown sugar is more addicting than some hard drugs. Viewed this way.. we’re all addicts. And keto’s our therapy.

Keto Flu symptoms include:

  • Dizziness
  • Fatigue
  • Irritability
  • Brain fog
  • Nausea
  • Sugar cravings
  • Stomach pain
  • Trouble sleeping
  • Insomnia

Don’t worry, it’s unlikely you will experience all of these symptoms. You may only experience 1 or 2. The length and severity of symptoms vary from person to person.

Who gets the Keto Flu?

Who gets the Keto Flu

Most – but not all – experience some degree of the keto flu. How much depends on your “metabolic flexibility,” or how easily your body can switch to run off different fuel sources. This depends on individual factors like genetics and lifestyle.

Those who live healthy, active lifestyles will usually have higher metabolic flexibility. Those who fuel off processed carbohydrates and sugars are in for a rude awakening...

How long does the Keto Flu last?

how long does the keto flu last

Keto Flu symptoms generally begin 24 to 48 hours after starting the diet. They last one week on average. In rare cases, they can last up to a month. One person even reported 6 months, but that’s really rare.

Why does the Keto Flu happen?

what causes the keto flu

Training your body to run off a new fuel source is no small feat. Remember, you’ve lived your who life on glucose. The switch requires major changes to your cells and hormones. You are actually changing your body chemistry.

Here are the Top 3 Reasons the Keto Flu happens:

1) Water and Electrolytes Leave the Body

You may have heard of insulin. It’s a hormone – and it’s primary job is to tell the kidneys when there is excess energy to be stored. Insulin is to blame when calories get turned into fat.

Eating carbohydrates raise insulin levels. When carb are cut out, insulin levels lower. This is part of the magic of the ketogenic diet. Lower insulin is responsible for the steady energy levels and weight loss you hear so much about.

It’s also part of the problem. You may not know it, but insulin has another job. It tells the kidneys to store sodium and water. When insulin levels lower, sodium and water quickly leave your body.

This process can flush up to 10 pounds of water out of your body in just the first 5 days of keto. This is why half of the initial weight loss on keto is water weight. Sorry to be the bearer of bad news!

Glycogen is the other culprit. Glycogen is the body’s stored version of glucose and depletes in the first 24 hours of carb-restriction. Each gram of glycogen is stored with 3 grams of water.

Lower insulin and glycogen are why you can experience dizziness, nausea, cramps, headaches, and gastrointestinal issues. Flooding yourself with water and taking electrolyte supplements are your best defenses against the keto flu. More on that later.

2) Cortisol Levels Increase

Yes, the stress hormone. By going on keto, you trick your body into thinking it’s starving (pretty crazy, right?). As a result, cortisol levels spike to keep you alert and awake. Hey you can’t go to sleep, you need to out there finding your next meal! Or so your body thinks..

Unfortunately this brings all the negative effects of stress. Cortisol is why you can feel irritable or have trouble sleeping.

The good news is cortisol levels usually return to normal levels once keto-adaptation is complete. Hang in there.

3) T3 Thyroid Hormone Levels Decrease

T3 is a hormone produced by the thyroid gland. Carbohydrates mediate thyroid function. With carbs out of your diet, T3 levels can fall.

Why does this matter? Thyroids hormones control more than metabolism -- they also regulate your body’s temperature and heart rate. Fluctuating levels in these hormones is why you might experience fatigue and brain fog.

Lower T3 levels also signal more of that nasty cortisol increase we just talked about. These factors can compound to make the Keto Flu really unpleasant.

7 Easy Ways to Cure the Keto Flu (and better yet.. stop it from ever happening!)

cure the keto flu

Okay now that we know why the Keto Flu happens, let’s talk about how to cure it. We’re going to share our Top 7 tools. These are easy, proven ways to make the Keto Flu history.

Listen up, following these from the start can put you in a lucky group -- those who never get the keto flu. As Benjamin Franklin famously said,

“An ounce of prevention is worth a pound of cure.”

1) Hydrate like crazy

stay hydrated on keto

We all know it’s important to hydrate. On keto, it’s not an option. If you don’t up your water intake, you will experience dehydration and all the nasty feelings that come with it.

Studies show it only takes a 2% loss of water (by bodyweight) to experience physical impairment. And at a 2.8% loss, your cognitive abilities suffer. The first 5 days of keto can cause easily do this to you. Yikes!

How much water are we talking? Take your bodyweight (in lbs) and divide by two. That’s how many fluid ounces you should drink each day. For example, a 150 lb person should drink 75 ounces of water per day (~1.25 gallons).

Better yet, add a pinch of mineral salt to a glass of water to replenish your sodium levels.

2) Supplement Electrolytes

supplement electrolytes on ketogenic diet

Sodium. Potassium. Magnesium. All these essential minerals will leave your body on keto.

Your best defense is to eat a diet rich in electrolytes. Foods like leafy greens (spinach), avocados, and nuts. But if you don’t fancy chowing down of raw spinach, supplementing is a great choice.

Salt. Don’t be afraid of it. You’ll soon realize without all those processed and packaged foods, you need more salt than you think. Many keto experts recommend 5,000 - 7,000 mg of sodium per day as you transition. Add healthy amounts to season your meals and try salty drinks like bone broth.

Potassium and magnesium can be harder. Find an affortable, trusted source on Amazon like this Potassium Gluconate and Magnesium Citrate. Magnesium is a known laxative – so ease into it!

Here are the Daily Recommended Amounts for each:

Sodium: 5,000 to 7,000 mg per day

Potassium: 3,500 mg per day

Magnesium: 400 mg per day for men, 310 mg per day for women

3) Eat. More. Fat. (especially MCT’s)

mct naturally occurring in coconut are perfect for keto

Starting on keto, many people remove carbs but don’t replace them with enough fat. It takes time to lose the guilt of pigging out on bacon or a juicy burger patty. We get it! But don’t make this mistake.

Adding fats will speed up the adaptation process. But beware, not all fats are created equal.

Animals fats have go through your entire lymphatic system before reaching your liver where they can be converted to energy.

MCTs – that’s medium-chain triglycerides – are different. They process directly in the liver and quickly convert energy. They’re everything carbs wish they were.

Grab an MCT supplement and add it to your favorite shake or morning coffee. Coconuts are also a great natural source of MCTs.

4) Get Plenty of Sleep

quality sleep for ketosis

This is the one week you might want to ditch that alarm clock. Getting enough sleep will lower cortisol levels and help with fatigue and brain fog.

Aim for 7-9 hours per night of quality sleep. Drinking sleepy-time tea (lime chamomile) and taking pro-slumber supplements like melatonin and magnesium will help you get damn good sleep.

5) Get the Right Kind of Exercise (No Crossfit!)

morning walk for ketosis

Exercise is a proven way to lower stress and increase energy levels.

But you may ask… how the heck am I supposed to exercise when I’m bed-ridden with the keto flu!? Great question -- your body is probably in no condition for extreme workouts.

Your best bet is stress-relieving exercise like yoga. Brisk walks in the morning are also a great way to get the blood flowing and kick your metabolism into gear.

An intense workout will raise cortisol levels and could make your symptoms worse. Those killer workouts will come as soon as your fat-adapted.

6) Meditate

meditate on keto

Meditation is a powerful way to reduce stress. And naturally lowering stress is your best defense against cortisol.

You might think meditation is this crazy ritual practiced only by monks in the Himalayans. Think again. At its core, meditation is sitting still and breathing for 15 minutes. Focus on your breath, and try not to let your mind wonder. Sounds simple, but it’s worth a try.

Yoga often has a meditation component (two birds with one stone!) or you can try a meditation app like headspace.

7) Eat Carbs (WHAT!?)

are carbs okay on a ketogenic diet

Yep. We said it.

Much like addicts are trained not to quit “cold turkey,” some keto-ers do better easing into ultra-low carb lifestyle. The more your diet runs on processed carbs and sugars, the more brutal your transition to keto will be.

If all else fails, try to incorporate nutrient-dense, “clean” carbs into your diet as you transition. You can try a baked sweet potato, half a banana in your smoothie, or a handful of berries.

Just don’t over do it! In time, your body will adapt. And those carb cravings will go away. We promise.


Don’t fear the keto flu. It’s a natural response to your changing state and easily treated. To recap, the cures are:

  1. Hydrate like crazy
  2. Supplement electrolytes
  3. Eat more fats
  4. Get enough sleep
  5. Exercise lightly
  6. Meditate and relax
  7. Eat carbs (but only if you must!)

Like all things, the keto flu will pass. And the incredible benefits of keto await: increased fat burning, steady energy levels, and a sense of well-being. You’re only a week away :)

To your health,

Ben & Brandon

Keep Reading: Keto Origins | How-to Keto | Recipes | Our Story

Follow us on Social Media: Facebook | Instagram 

  • Keto Coffee

  • Leave a comment