What Causes Keto Headaches? (And What To Do About Them)

A lot of people ask me about headaches on keto. They want to know if they’re normal, why they happen, and how to make them go away.

Keto headaches are normal as you transition to low-carb dieting. They can also occur in veteran keto dieters that are dehydrated. And I don’t just mean water. It’s both ends of the hydration coin—water and electrolytes.

Both situations are fixable. Later, I’ll share tips for preventing and reversing keto headaches.

If you’re doing everything right and your keto headaches persist, keto may have nothing to do with them. A long list of medical and lifestyle factors is linked to chronic headaches. We’ll explore these too.

We’ll also explore how the ketogenic diet is a promising therapy for migraines. Done right, keto is a force against headaches. Keto can be a headache cure as well as a headache cause.

What Causes Headaches?

A headache is defined as a continuous pain in the head. If the headache is sufficiently intense, it may be described as a migraine.

Migraines typically affect one side of the head and are often accompanied by nausea and light sensitivity. They’re considered the number one contributor to disability in those under 50 years old.

The origins of a headache can be mysterious. There are many potential causes: brain inflammation, dehydration, electrolyte issues, low blood sugar, stress, sleep, the list goes on.

In a 2017 review published in the journal Neurology, researchers examined 27 studies on people with chronic headaches. The studies were either randomized controlled trials (the gold standard of science) or high-quality observational studies. The objective was to find factors that predicted headache occurrence—in other words, what might cause headaches. Here are the predictive factors supported by “moderate quality evidence”:

  • Depression and anxiety
  • Medication overuse
  • Poor sleep
  • High stress

Other factors with lower quality evidence included age, BMI, and employment status. One interesting tidbit was that those with higher expectations for a headache therapy (like acupuncture) tended to benefit more from the therapy.

The takeaway is to start with things like sleep, stress, mood, and medication when unraveling a headache problem. If the headache appears specific to keto, there are a few more factors to add to that list.

We’ll cover those factors in a bit. First let’s talk about the use of the keto diet as a headache cure.

Keto for Headaches

Since 1928, researchers have known that the keto diet can help with headaches. That was when the first case series suggested keto provides migraine relief. More recently, another study found that one month of keto dieting reduced the frequency and duration of headaches in a group of 18 migraine sufferers.

Larger studies show promise too. For instance, one study from The Journal of Headache and Pain found that 108 migraine patients showed a 90% response rate to the keto diet, as opposed to no effect from a low-calorie diet.

Why might keto help with headaches? In a word: ketosis. Consider the following:

  • A state of elevated ketones (ketosis) appears to be protective against traumatic brain injury and therapeutic for neurodegenerative disease.
  • Compared to glucose, ketones are a cleaner burning and more efficient source of energy for the brain.
  • The aging brain loses its ability to use glucose but not its ability to use ketones.
  • Beta-hydroxybutyrate (the main energy ketone) suppresses the NLRP3 inflammasome, a driver of inflammation.

Inflammation reduction may be the key to why keto helps with headaches. The keto diet reduces brain inflammation, and brain inflammation has been linked to migraines.

But if your headache is caused by keto (directly or indirectly), inflammation probably isn’t to blame.

Causes of Keto Headaches

Many things can cause a headache. But a headache specific to keto? That shortens the list. Here are the main causes of keto headaches:

#1: Transitioning to ketones

Your brain normally runs on glucose for energy. When you eat carbohydrates, those carbs break down to glucose and cross the blood-brain barrier to power your neurons.

When you go keto, you stop eating carbs for the most part. This decreases the brain’s glucose supply, which can result in headaches, brain fog, and hunger.

Glucose isn’t the only brain fuel though. Lactate, pyruvate, medium chain triglycerides (MCTs), and ketones can also cross the blood-brain barrier to sate your brain’s ravenous appetite.

Ketones are the big one here. On a keto diet, ketones become the main source of fuel for your brain. That’s why your liver creates ketones out of fatty acids. You need the backup brain fuel.

But the brain takes time to keto-adapt. It might take a few hours, a few days, or in rare cases a week or more. Once the brain is running on ketones, the lower supply of glucose doesn’t matter. Ketones are the fuel now.

#2: Too many carbs on keto

Carb restriction is the fundamental rule of the keto diet. Restricting carbs keeps the hormone insulin low, and low insulin tells your liver to start burning fat and making ketones.

A good rule of thumb is to keep carbs below 10% of daily calories. (Around 30 grams of net carbs per day). This level of carb restriction is generally sufficient for ketone production (ketogenesis) to commence. These ketones can then fuel your brain.

A higher carb diet (over 100-150 grams of carbs per day) also provides lots of brain fuel as glucose. It’s in the middle—low-carb but not keto—that things get tricky.

For example, if you eat 50 grams of carbs per day, that might be too high to make ketones but too low to provide adequate glucose for the brain. Understand that the brain consumes about 120 grams of glucose per day when ketones aren’t around.

True, you have glucose backup systems. You can make your own glucose (gluconeogenesis) and access stored glucose (from glycogen), but these sources are likely inadequate to feed a glucose-hungry brain.

#3: Dehydration

A lot of keto flu symptoms (including headaches) are blamed on dehydration. Thanks to all this press, most people on keto tend to drink enough fluids.

To be clear, the keto diet does have a diuretic effect. This is driven by low levels of insulin, which signal the kidneys to excrete more water.

What about all the water lost from glycogen breakdown? Doesn’t that cause dehydration symptoms?

This is a common point of confusion. While it’s true that glycogen is mostly water, accessing that water by breaking down glycogen doesn’t decrease blood volume. (Blood volume is a primary marker of hydration status).

In fact, breaking down glycogen increases blood volume. When you split apart glycogen, you release water into circulation. Eventually, you pee it out, but that water needn’t be replaced. On keto, you operate in a glycogen-depleted state. 

#4: Electrolyte disturbances

If you’re several days into keto and the headaches still haven’t resolved, you’re probably low on electrolytes.

There are two main reasons keto dieters tend to be short on these crucial minerals:

  1. Low insulin levels on keto increase electrolyte loss through urine.
  2. It’s hard to consume enough sodium and potassium on a healthy low-carb diet.

Let’s talk about reason two. It’s hard to get enough sodium on keto because most dietary sodium comes from refined foods. When you eliminate these pseudo-foods, the salt shaker needs to work overtime.

And it’s hard to get enough potassium because many potassium-rich foods are too high-carb to be keto. This list includes potatoes, carrots, and most fruits.

Deficiencies in both these electrolytes can cause headaches. What dosage do you need for optimal health? Based on published evidence, shoot for 5000 mg sodium and 4700 mg potassium per day from diet and supplements.

Keto Headache Remedies

The cures for keto headache follow from the causes above. Here’s a quick list:

  • Allow a grace period. Allow at least 3 days for transitioning from glucose to ketones. But also mind the other tips during this period.
  • Take MCTs and exogenous ketones. During the grace period, use MCT oil and exogenous ketones to raise ketone levels and mitigate symptoms.
  • Watch your carbs. If you’re low-carb but not keto, you might find yourself short on both glucose and ketones to fuel your brain. That will make your brain sad.
  • Eat electrolyte-rich foods. Meats, nuts, and leafy greens are good sources of potassium and magnesium. Check out this post to learn more.
  • Be liberal with the salt shaker. 5000 mg of sodium per day (the bare minimum for keto folks) is 2.5 teaspoons of salt. A pinch of salt won’t stop keto headaches. Salt liberally.
  • Drink electrolyte water. This bullet is probably the best keto headache “hack”. To hydrate without diluting blood sodium levels, add electrolytes (especially sodium) to your water and drink to thirst. LMNT Recharge makes this easy.

Will these tips cure every headache? Of course not.

Most keto-related headaches, however, won’t withstand them. Give them a shot and let me know how it goes.