Keto headache

Fact-checked by Dr. Anthony Gustin, DC, MS.

Written by Lorenz Mac

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One of the most common complaints about transitioning into a low carbohydrate, high fat ketogenic diet is the dreaded low carb or keto headache.

Unfortunately, this initial side effect prevents a large amount of dieters from experiencing the powerful benefits to this way of eating.

But the flu-like side effects in the beginning of your ketogenic journey should not discourage you.

There are specific lifestyle hacks and nutrient protocols you can take to prevent low-carb induced headaches.

Eventually your body will adapt to using fats as energy and the symptoms will disappear.

Let’s dive into the reasons why you are experiencing a keto headache and the steps you can take to prevent it.

This article will help you understand:

What Happens to Your Body When You First Go Keto?

There’s a good chance you’ve spent a good portion of your life feeding your body large amounts of carbohydrates, many of them from processed sources.

This means your cells, hormones, and brain have adapted to using carbohydrates as its main source of energy for the body.

Transitioning to a fat dominant fuel source will confuse your body’s metabolism in the beginning.

This metabolic confusion will put your body through an “induction phase”.

This is the time when your metabolism works in overtime to become accustomed to using ketones for energy (from fats) rather than glucose (from carbohydrates).

During this phase, you may experience flu-like symptoms — which is called the “keto flu” — especially headaches and brain fog — because your body is going through a physical withdrawal from carbohydrates.

Mental Fog is Normal at the Start of Keto

One of the very first signs of this “induction phase” comes from your brain losing its main source of fuel, glucose.

If you have never followed a low carb high fat diet, your brain has used carbohydrates as its main energy source.

When you start increasing your fats and restricting carbs, your body starts to burn through the last stores of glycogen remaining in your body. At first, your brain won’t know where to find energy because of the lack of carbohydrate.  

It’s normal to start staring off into space, experiencing headaches and becoming irritable.

A good way to combat these symptoms is to go as low carb as possible when you’re first starting out. This way your body is forced to use up all of its glycogen stores much faster.

Many people try to taper off their carb intake over time but doing so will only make the brain fog last longer.

When you get into a state of ketosis, a large portion of the brain begins to burn ketones instead of glucose. It can take a few days up to a couple weeks for the transition to happen.

Luckily, ketones are a highly potent fuel source for the brain. So once your brain gets used to using fats as energy, brain function is optimized.

Many studies have shown long-term ketogenic dieters to have improved brain cognition and has even been tested for treating brain conditions such as memory loss[*][*][*].

The Keto Induction Phase Is Stressful on Your Body

Without any sugar from carbohydrates present, your body will begin to decrease blood sugar levels and also increase the stress hormone, cortisol.

Cortisol is a glucocorticoid hormone released by your adrenals to make sure you have enough energy to survive. And when you have low blood sugar levels, your brain sends a signal to your adrenals to release cortisol.

Your body will begin to burn glycogen (stored glucose) for fuel.

Overtime, your body will prefer to use fat as fuel through ketosis.

It may sound like a bad idea to restrict carbohydrates due to the increased stress placed on your body, but eventually your body will adapt.

In theory, it would seem that the ketogenic diet should be avoided because of the release of additional cortisol, but this simply isn’t the case.

One study in particular tested three separate diets: a low carb diet, a low fat diet, and a low glycemic diet. This study showed that the different diets had significantly different metabolic effects with the low carbohydrate diet proving to be most effective[*].   

The Dreaded Keto Headache

One of the most common symptoms when going low carb is the pounding headache that discourages many people from sticking to the ketogenic diet.

When your body has been running off carbs its whole life, making a large transition to burning fat as fuel will require an adjustment period.

The keto headache is a symptom that comes with the keto flu and it shouldn’t be compared to the normal flu.

What Causes the Keto Headache?

There are three main reasons why you begin to experience a headache after going low carb; dehydration, electrolyte imbalances and carbohydrate or sugar withdrawal.

The traditional Western diet involves a large amount of sugar which gives our body an instant rush and satisfies our body.

In fact, sugar impacts our brain through the same reward system that is seen with equally addictive substances like cocaine.

It’s this “sugar high” that keeps us from craving more sugar the more we eat it.

This is a large reason why we begin to experience symptoms similar to drug withdrawals, because it’s working in the same reward system in the brain.

How Long Does the Keto Headache Last?

Some people may not experience any withdrawal symptoms at all. Everyone is different and the length of the symptoms depend on several factors.

For example, if someone followed a diet relatively low in carbs before going keto and ate large amounts of green vegetables (or took a high quality greens supplement), there’s a chance that the symptoms will be very short-lived or even non existent.

On average the keto headache will last anywhere from 24 hours to one week.

In rare cases, it can take up to 15 days for the symptoms to subside.

Some people will prefer to start on the weekend so the symptoms are more tolerable and won’t affect everyday life too much.

Dehydration is Common During The Keto Induction Phase

When you adopt a low carb high fat ketogenic lifestyle, your body begins to excrete excess water.

Don’t get too excited when you notice a lot of weight lost after getting on the scale. That weight loss isn’t all from fat loss, it’s water being flushed out of your body.

Being in ketosis is also known for its high salt content and strong diuretic effect.

This means your body is excreting both water and electrolytes which leads to the lack of retention of water on your body.

Water is stored in your body from carbohydrates and when you restrict carbohydrates, your body begins to excrete water rapidly.

For each gram of glycogen (from carbs) used as energy, twice the mass is lost in water.

Once your body enters ketosis, your body starts sparing glucose but, water loss continues. Having ketones present in your body will lead to more water excretion.

Electrolyte Imbalances Are Common When You First Go Keto

The main electrolytes to keep a close eye on are magnesium, sodium and potassium.

When your body excretes water from the body, you begin to flush out these essential electrolytes needed for optimal brain and body functioning.

They are crucial for several different bodily functions like energy production, body temperature control and optimal brain function.

Each of the daily electrolyte requirements are higher on a ketogenic diet compared to a normal diet.

Sodium Requirements

Insulin plays a huge role in electrolyte maintenance. It is a hormone that lowers our blood sugar when it’s too high.

The main job of insulin is to shuttle sugar into cells so they can use it as fuel and deposit excess sugar into fat. It also works to promote sodium absorption in the kidneys.

When you start a low carbohydrate diet, insulin levels are much lower.

The sodium eventually draws more fluid into your kidney to prepare excretion of water.

Less insulin in the body means there is less sodium present in the body.

A lack of sodium present in your body is one of the main reasons why people begin to experience fatigue and headaches on a low carb diet.

You should aim for 5,000 to 7,000 mg of sodium throughout the day.

This can be consumed in the form of pink himalayan sea salt, bouillon, bone broth and even sodium pills.

Potassium Requirements

If you are potassium deficient, you can expect to experience depression, irritability, constipation, skin problems, muscle cramps and heart palpitations.

To combat this you should consume ~3,000 mg of potassium a day.

Here is a list of keto-friendly foods that contain ample amounts of potassium:

  • Nuts — ~100 – 300 mg per one oz serving
  • Avocados — ~1,000 mg per serving
  • Salmon — ~800 mg per serving
  • Mushrooms — ~100-200 mg per serving

It’s important to mention that having too much potassium can be dangerous. While it would be difficult to reach the upper threshold of toxic levels, it’s best to steer away from potassium supplements and stick to the natural sources listed above.

Magnesium Requirements

While magnesium is not as common of a deficiency for low carb dieters, it’s important to be aware of maintaining optimal levels.

A magnesium deficiency can lead to muscle cramps, dizziness and the keto headache.

The recommended daily average for people on the ketogenic diet is ~400 mg of magnesium a day.

Here is a list of keto-approved magnesium rich foods:

  • Cooked spinach — ~75 mg per cup
  • Cacao powder with dark chocolate — ~80 mg per one tbsp of cacao powder
  • Almonds — ~75 mg per 1 oz
  • Salmon — ~60 mg per fillet

How to Prevent a Keto Headache

The headache you get when you convert to burning fat for fuel comes from an impaired ability to effectively use fat as energy.

Anytime our body’s ability to burn fat is impaired, we have a hard time losing weight and become very hungry when our blood sugar runs out no matter how much fat we have available to burn.

To combat the keto headache, you must improve your body’s metabolic flexibility to burn fat as energy instead of glucose.

Metabolic flexibility is your capacity to adapt fuel oxidation into fuel availability.

This is your body’s ability to switch from one source of fuel to the next (from carbohydrate to fat).

Your keto headache symptoms will soon diminish once you become used to using fat (ketones) as energy.

Here are five techniques you can implement today to prevent the keto headache:

#1: Drink Water and Salt

When you start eating low carb, your insulin levels will naturally lower which means you won’t hold onto as much sodium as compared to a traditional Western diet with a moderate amount of carbs.

You also begin to excrete water that your body has been holding onto when you restrict carbohydrates.

Sodium deficiency is one of the main causes of the keto headache and can be mitigated by adding more water and salt into your system.

It’s important to increase the amount of salt you consume because drinking more water will flush out sodium at the same time.

Consuming bouillon or bone broth will help you maintain proper amounts of sodium.

If you are still having difficulty increasing your salt intake on a low carb diet, supplementing with sodium supplements and simply adding more salt to every meal will help.

#2: Eat More Fats

Eating more dietary fat will help your body get accustomed to using fats as energy. Since you’re replacing carbs with fats as your main source of calories, you need to consume larger amounts of fat than you were previously.

You should aim for 65% – 70% of total calories from fats.

Taking the time to track your fat intake should be a priority in the beginning because it’s very easy to undereat fats. This is because fats are more calorically dense and will fill you up quicker.

Eat fatty meats like rib-eye steak, bacon, salmon and chicken thighs. Add coconut oil and butter to each meal to increase your fat intake.

#3: Take Supplements

Supplements can greatly help your body convert to a fat-fueled machine.

But it’s important to never use supplements as a replacement for any dietary deficiencies.

Some key vitamins and minerals that can help mitigate a keto headache include:

  • L-carnitine. High fat intake from the ketogenic diet means more fatty acids need to be moved into the mitochondria for fat oxidation. Carnitine is required required for effective transportation.
  • Co-Enzyme Q10. CoQ10 is an antioxidant that is responsible for the cellular process of creating energy. It is another supplement that helps mobilize fat and will help you transition into ketosis faster.
  • Omega-3 fatty acids. Fish oil supplementation is a potent natural anti-inflammatory and will help contribute to a low carb, high fat diet. Consuming omega-3’s also help lower triglycerides in your body which are fat molecules held in the blood to be stored for later use.

#4: Exercise More

Studies have shown that exercise can improve your body’s metabolic flexibility.

Exercising increases both fat utilization and improves weight loss, both are contributing factors to combating the dreaded keto headache[*].

One study shows that the benefits of exercise go beyond weight loss. It also helps to repair broken metabolisms. This study showed that after exercise, type 2 diabetics metabolisms’ were restored and were able to utilize calories for energy more efficiently[*].

Making a habit to work out will help you regain your metabolic flexibility and stimulates your body to burn more fat during exercise and at rest.

Exercise will greatly improve the speed in which your body starts using fat as its main source of energy and will help mitigate symptoms of the keto headache.

#5: Supplement with Exogenous Ketones

Taking exogenous ketones is an effective way to elevate your ketone levels even if you haven’t been fully converted into using using fats as a primary source of energy. They can elevate your beta-hydroxybutyrate (BHB) levels by up to 2 mMol after consumption.

Exogenous ketones cause blood glucose to decrease due to an increase in insulin sensitivity. This is important during the induction phase because you’re priming your body to start preferring fats as energy instead of carbohydrates.

They also contain ample amounts of calcium, magnesium and sodium which are critical electrolytes your body needs for peak brain and body functioning.

By adding exogenous ketones into your routine, you will drastically mitigate the severity of your ketogenic induced headaches.

Don’t Be Discouraged By The Keto Headache

While the keto headache may sound daunting and can even discourage you from adopting a ketogenic diet, taking the steps to mitigate the symptoms isn’t as hard as people make it out to be.

Replacing essential nutrients and minerals, exercising frequently and maintaining a proper low carb high fat diet will ensure that your keto flu-like symptoms will diminish sooner than later.

Remember that the keto headache is a normal, induction stage of the process and happens to most of the people who adopt this way of eating.

The light at the end of the tunnel is much closer than you think and we encourage you to stick it out until you begin to experience the benefits of a low carb, high fat ketogenic lifestyle because it will make it all worth it.

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Responses (17)

  1. I began my keto journey 3mnths ago.

    Amazing results so far.
    I feel amazing and have lost 6inches in my waist.

    After I was told of a mild fatty liver, adrenal body type.
    I decided to research on a healthier lifestyle.

    Present day…I feel so much healthier and alive, fueling my body this way.

  2. Thank you for this excellent article. I’m 77yrs. old and am not ready to give up. Been doing the keto plan for one and a half months. I’m doing so good except for a slight headache. You’re very encouraging. Being a woman, i love life.

  3. Thank you, Erin, and congratulations! It’s almost 2 months later – how are you doing? It’s been almost four weeks for me, and I’m battling bad headaches. Did this happen for you? What helped you through it?

  4. Thought my electrolytes were low, giving me the keto headache. Searching the 7-11 near my office, I saw packaged pickles… plenty of sodium. Ate a whole one and it quickly alleviated the symptoms. Hours later, headache started coming back, so I downed another pickle. Worked well. I’m gonna remember this.

  5. This is my first day of Keto and my head started hurting. probably doesn’t help that before today I’ve been living off of chips, pretzels, Nutella, chocolate candies, pickles, and cheese. My body is not sure what to do with itself right now I guess. Pickle and avocado helped the headache exponentially!!

  6. Thank you Rob. That’s awesome. Have a keto headache right now but also have a full jar of pickles. I am going to try it.

  7. Great article! Thank you for breaking this down a bit more. I’m new to this, so this was quite helpful!

  8. I thought I had avoided the keto headache because I had been eating fairly low carb before I started keto. Wrong, I have had a headache on and off for the last three days. It kept me awake most of the night so today I feel worse than ever. I just ate a cheddar cheese stick and it seemed to help but I’m not sure if that’s real or just my imagination. I think it may have been the salt in the cheese but I guess time will tell.

  9. I’ve been on the the Keto diet for a week. I woke up in the middle of the night with a headache. I had a few almonds with almond butter and water with salt. It seem to help with the headache.

  10. Please check you data on sodium. 5-7 gms/day of sodium is 12.5 – 17.5 gms/day of salt. That is “off the charts” high. The healthy range of salt intake is 5-12 gms/day and the recommended daily allowance is <6 gms/day. Did you mean to say salt instead of sodium?

  11. I wonder if you can adjust your numbers for body size and dietary intake. I have read that to be in mild ketosis you have to keep carbs under 70 gms/day and the full ketogenic diet calls for <30 gms/day. I am 84 years old, weigh 160 lbs and have a daily caloric intake <1400 calories. I have been under 60 gms/day of carbs for 18 months, have lost 6 lbs and maybe 2 inches. Have just started exogenous ketones to see if that will help. Does the 70 gms/day apply only to the youthful consuming 2500 calories/day? Do I have to get under 40 gms/day? Please advise.

  12. This is my first day of ketogenic diet.I have a really bad headache. I hope I can stick to my diet. Also, I wanted to ask if it is okay to fast during keto.

  13. Thank you for this wonderful article.. finally found the real cause of headache during the keto diet.. try to consume himalayan pink salt along with food and water to enhance the sodium intake..

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