What is the Keto Flu?

what is 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.”

Did you feel 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 conquered with 7 simple cures.

What is the Keto Flu?

what is the keto flu?

The Keto Flu is your body’s responding to switching from running off glucose to ketones (glucose from carbs. Ketones from fat).

Remember you’ve spent your entire life running off glucose. Keto is a shock to the system. And it’s normal to feel funky during the transition.

Keto flu symptoms are similar to what addicts experience from withdrawal. It’s 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. How “sick” you get depends on your metabolic flexibility – how easily your body can switch between different fuel sources. Factors like genetics and lifestyle drive flexibility.

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

How long does the Keto Flu last?

how long does the keto flu last?

Keto Flu symptoms generally start 24 to 48 hours after starting the diet. They last one week on average. In rare cases, they can last up to a month.

Why does the Keto Flu happen?

why does the keto flu happen?

Training your body to run off a new fuel source is no small feat. Switching requires major changes to your cells and hormones.

Which leads to...

1) Water and Electrolytes Leave the Body

Insulin tells your kidneys when there is excess energy to be stored. It’s to blame when calories get turned into fat.

Carbs drive insulin levels. When carbs are cut out, insulin levels lower. This is part of the magic of the ketogenic diet.

It’s also part of the problem. You see 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 the first 5 days of keto. This is why half of the initial weight loss on keto is water weight (sorry for the 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.

2) Cortisol Levels Increase

Yes, the stress hormone. Going on keto, you trick your body into thinking it’s starving (pretty crazy, right?).

Cortisol levels then 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..

But with Cortisol comes those stressed out feelings. It’s also why you can feel irritable or have trouble sleeping.

The good news is cortisol levels usually return to normal levels once you adapt. 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 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.

The Bottom Line

Don’t fear the keto flu. It’s a natural response to your changing state and easily treated.

Like all things, the keto flu will pass.

Especially if you follow our 7 simple cures.

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










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