Does Keto Cause Headaches?

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Written by Edibel Quintero, Medical Doctor and medically reviewed by Abby Courtenay

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Can a low-carb diet cause headaches? How can healthy eating make me feel bad? It doesn't seem to make sense, does it?

Starting a new diet is a whole journey of new feelings, and they are not always positive. Even though you want to change your lifestyle to feel better, there will always be some discomfort that can make you hesitate.

It may be paradoxical that a low-carb diet can improve migraines, while at the same time it can cause headaches. How is this possible?

As we’ll see in this article, keto headaches are a common side effect of changing your diet, but only as part of the initial metabolic adaptation process when you first begin. 

And the good news doesn’t stop there. Fortunately, there are proactive steps you can take to prevent this symptom, plus, the ketogenic diet may actually be an effective tool for improving chronic migraines.

At PlanKetogenic, we bring you updated information on this common complaint that can occur during the keto diet, how to avoid it, and also how to make it go away.

Headaches, migraines, and the keto diet

First things first, let’s get our terms straight.

Headache and migraine have many similarities but are actually different disorders. Anybody can get a headache, but only part of the population suffers from migraines, which are a neurological disease.1 

Migraines can cause many different symptoms, including severe headaches, dizziness, nausea, fatigue, sensory disturbances, and/or heightened sensitivity to light, sound, or smells. 

As a neurological disorder that affects the structure of the brain, migraines can improve when following a keto diet as this way of eating can regulate brain functions and may decrease inflammation.

Migraines do not have one specific cause, although some caffeinated or fatty foods can worsen or trigger them.

On the other hand, headaches usually have a primary and recognizable cause. They can be a result of stress, eyesight problems, drinking too much alcohol, not drinking enough water, or not eating enough, to name just a few common ones. Or, they can be a symptom of another underlying condition, such as migraines or even a case of the common cold or flu.


Why does keto cause headaches?

Two big reasons keto can cause headaches are dehydration and lack of sugar


Low-carb headaches are expected when you switch to a regimen that involves consuming less sugar and starchy carbohydrates, since even the healthiest carbohydrates must be restricted in order to trigger ketosis.

When carbohydrate intake decreases drastically, a large amount of the water in your body is lost. This is because carbs help the body store water.

Glycogen2 is the form in which carbohydrates are stored in muscle tissue and liver. The glycogen molecules hold onto a substantial amount of water.  When you stop eating large amounts of carbohydrates, these glycogen reserves are depleted and therefore, water is lost.

This loss can cause dehydration, which if not treated in time can cause severe headaches.

Lack of sugar

The keto headache may be accompanied by other symptoms very similar to the flu, this is a syndrome known as "low-carb flu" and is very common3. This occurs in response to sugar restriction. 

Going from an intake of over 60% carbohydrates, which is typical for most people, to eating only 5 - 10%4 of this macronutrient is definitely going to cause both positive and negative physical manifestations. Fortunately, the negative side effects only occur in the beginning and are short-lived if you take the right steps.


Can going into ketosis cause headaches?

Ketosis is a complex biochemical process that converts fatty acids into ketone bodies, which are then used by your brain as a source of energy.

Can ketosis cause headaches?

Yes, the excess of fats that are mobilized in the blood to be used as energy can disturb the balance to which your body has become accustomed.

Therefore, if you suffer from headaches when starting keto, the diet may be the culprit because of all the changes that are occurring in your body.

Once your body has adapted to functioning without glucose and relying on your fat stores, this and other symptoms will gradually disappear. The other symptoms that can occur are nasal congestion, fatigue, dizziness, and malaise (which is a general feeling of being unwell).

How long does a keto headache last?

Ketogenic diet headaches can last from one week to one month. If they do not disappear or even worsen, consult your doctor to evaluate your overall health.

The discomfort caused by this type of diet is temporary and its duration will depend on taking precautions in time. You should watch your salt intake, drink enough water, and avoid stressful situations that may trigger this symptom.

How to stop headaches on a ketogenic diet

Suffering from a headache due to low carb consumption is a common occurrence, especially if you were used to eating large amounts of this macronutrient. Removing tempting high-sugar treats from your diet can be tough as they are highly addictive products.

To stop low-carb headaches, try these remedies for relief:

  • Drink lots of water during the day, especially if you do activities that make you sweat a lot.
  • Add enough salt to your food (keeping in mind that packaged or prepared foods often already contain salt). Adequate sodium intake is essential to keep this symptom at bay.
  • Ensure you’re getting enough potassium by eating foods such as avocado and mushrooms.
  • Don't leave out foods high in magnesium, such as green leafy vegetables and peanut butter. You may want to consider a magnesium supplement.


How to avoid headaches on keto

If you’re reading this in time to prevent keto headaches before they begin, here are some tips:

  1. Go easy at first. Ease yourself into the diet gradually so your body has time to acclimate. Sometimes starting with too much enthusiasm and desire to lose weight fast can cause you to make mistakes.
  2. Do not reduce your sugar intake abruptly. Restrict your carbohydrate intake progressively, decreasing the amount each day until you reach your goal of 5-10% carbs.
  3. If you feel weak or tired, avoid intense physical activity until your body has adapted to ketosis. After this stage, your body will have energy and vitality to train effectively to burn fat. 

Migraine sufferers should also follow the recommendations above.

If your migraines get worse on keto, it’s a good idea to: 

  • Stop eating foods that may be triggers. Dark chocolate, artificial sweeteners, cheeses, and cured meats are allowed on the keto diet but can trigger migraines. You may want to try removing them from your diet to see if your symptoms improve. 
  • Make sure you are getting enough sleep.
  • Keep your stress levels low.
  • Consult your doctor to find out if there is a trigger that you may not have not identified yet.


Does keto help with headaches or migraines?

Suffering from headaches from hunger is common due to a sudden drop in blood glucose.

With regards to migraines, yes, several studies on the keto diet have demonstrated its possible association in the metabolic regulation of the brain and therefore act in the prevention of migraine episodes.5

This occurs because when blood sugar is low, ketone bodies are used as a source of energy and act as signaling molecules that modify the behavior of mitochondria in brain cells and decrease brain excitability and inflammation.6  In this way, the brain is relieved of tension and migraine episodes improve noticeably. 

Other headache-related side effects of a low-carb diet

Usually, the headache does not come alone. The classic keto flu presentation includes symptoms such as dizziness, generalized weakness, nasal congestion, nausea, tiredness, and all the typical flu-like discomfort.

When you begin to implement a low-carb diet, you may experience headache and nausea first due to the decrease in blood sugar. The body will be actively working on building alternate fuel through fatty acids supplied by your body reserves.

In addition, you may be more irritable or feel like your mind is foggy because quitting sugar is difficult and requires a great deal of commitment and discipline. Apart from the emotional effort required to change habits, the brain causes these symptoms due to the glucose deficit while it is getting used to the new metabolic state under which it will function properly.

Fortunately, within two weeks, your energy is renewed and you begin to feel the benefits of ketone bodies as regulators of brain function.


When to worry about headaches on keto 

Having a severe headache on a low-carb diet is a warning sign. Although it is a common symptom at the beginning of the diet, you should always evaluate your general health with your doctor, especially if the symptom does not go away.

Even though we at PlanKetogenic are enthusiastic about the keto diet and have found great health benefits from practicing it, we know that not all diets fit all bodies. It is crucial that you know how to read the signals your body is giving you so you can treat them in time.

Following a healthy ketogenic diet, resembling the clean keto diet, together with drinking enough water, will give you all the nutrients (including electrolytes) that you need to be healthy and avoid keto headaches.


Closing points

Headaches from not eating enough carbs is a common symptom that keto dieters may face in the beginning. While the process of activating ketosis may be one of the causes, your habits, stress levels, physical activity, and food choices must also be taken into consideration.

Any change of habits requires tolerating certain side effects that the body will manifest during the adaptation phase.

This does not mean that you must accept suffering, but rather you are encouraged to do your best to choose healthy foods, continue to stay away from sugary high-carb foods, read the recommendations carefully, and stay calm.

Before you begin any new diet, it’s recommended that you undergo a complete check-up of your general health and speak with your doctor about whether this type of regimen is right for you. Dietary changes can have a big impact on the body and must be handled responsibly.


1. The Trustees of the University of Pennsylvania: Migraine vs. Headache: How to Tell the Difference. 

2. Paredes-Flores MA, Mohiuddin SS. Biochemistry, Glycogenolysis. [Updated 2021 Nov 15]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. 

3. Harvard T.H. Chan School of Public Health, Harvard University. The Nutrition Source: Diet Review: Ketogenic Diet for Weight Loss

4. Bostock, Emmanuelle C S et al. “Consumer Reports of "Keto Flu" Associated With the Ketogenic Diet.” Frontiers in nutrition vol. 7 20. 13 Mar. 2020, doi:10.3389/fnut.2020.00020 

5. Barbanti P, Fofi L, Aurilia C, Egeo G, Caprio M. Ketogenic diet in migraine: rationale, findings and perspectives. Neurol Sci. 2017 May;38(Suppl 1):111-115. doi: 10.1007/s10072-017-2889-6. PMID: 28527061. 

6. Gross EC, Klement RJ, Schoenen J, D'Agostino DP, Fischer D. Potential Protective Mechanisms of Ketone Bodies in Migraine Prevention. Nutrients. 2019 Apr 10;11(4):811. doi: 10.3390/nu11040811. PMID: 30974836; PMCID: PMC6520671. Potential Protective Mechanisms of Ketone Bodies in Migraine Prevention. Nutrients. 2019 Apr 10;11(4):811. doi: 10.3390/nu11040811.