Ketogenic diet: why it causes headaches and what you can do

By | May 16, 2023

The ketogenic diet began as a way to control seizures. However, in recent years it has caught the attention of those who want to lose weight. But since this involves a reduction in carbohydrates, there will be some side effects when starting it. And a side effect that many people experience is headaches.

What happens to your body when you follow a ketogenic diet

On a ketogenic diet, you limit your carbohydrate intake to 5% to 10% of your daily calories. You will consume about 70% to 80% of your daily calories from fat and about 10% to 20% from protein.

The main goal of the ketogenic diet is to get your body into ketosis. Ketosis occurs when your body switches to burning fat because there aren’t enough carbs to burn for energy. When your body breaks down fat, it makes ketones.

As your body switches to burning fat, you may experience unpleasant side effects. The term “ketoflu” is commonly used to describe the side effects that occur when starting the diet.

Signs and symptoms of keto flu

When you switch to a low carb diet, it takes time for your body to adjust. For some, keto flu symptoms can start to show up within days of cutting carbs. Symptoms usually peak in the first week and gradually disappear by the fourth week of the diet.

The severity of symptoms can range from mild to severe, depending on the individual. The most common symptoms of ketoflu include:

  • Headache
  • brain fog
  • Stomach pain/upset
  • motion sickness
  • flu-like symptoms
  • Fatigue
  • Dizziness
  • Sore throat
  • Body pain
  • feeling faint
  • Changes in heart rate

Causes of headache

There are many possible causes of headaches during the first few weeks of starting the ketogenic diet.

low blood sugar

On a high-carb diet, your brain feeds on glucose, a type of carbohydrate. When you start a ketogenic diet, your body begins burning stored fat for energy instead of glucose. So when ketosis occurs, it could cause your blood sugar levels to drop. This is known as hypoglycemia. Hypoglycemia can cause a dull, throbbing headache at the temples.


As our body begins to shift into a state of ketosis, we begin to urinate more frequently, which can lead to dehydration. During the transition, your body uses stored glycogen for fuel. Glycogen in your body binds to water, releasing excess water as glycogen stores are depleted.

This is why many people notice tremendous weight loss within the first few days of starting a very low-carb diet. So if you don’t drink enough fluids while on the keto diet, it can lead to dehydration and headaches.

electrolyte imbalance

When you restrict carbohydrates, your body naturally produces less insulin. A drop in insulin causes your kidneys to excrete more sodium. Dehydration can also lead to sodium, magnesium, and potassium imbalances.

In addition to headache, low levels of sodium in the body can cause nausea, vomiting, fatigue, and cognitive decline.

Headache treatment and prevention

Fortunately, there are ways to manage and even prevent headaches when starting the ketogenic diet. It is essential to stay hydrated and eat a nutrient-dense diet to minimize the risk of dehydration and headaches.

drink plenty of water

When you first start the keto diet, your body will lose water weight, so it’s important to stay hydrated.

Get More Sodium, Potassium, and Magnesium

When levels of key electrolytes like sodium, potassium, and magnesium are low, it’s important to replenish them. Water is necessary for

stay hydrated, but you will need to replenish your electrolytes through the food you eat or an electrolyte supplement.

Potassium-rich foods include:

  • Avocado
  • Fungus
  • Pumpkin seeds

Good dietary sources of magnesium are:

  • cashew nuts
  • Peanut butter
  • Dark chocolate
  • leafy vegetables

You can add more salt to your food to increase your daily sodium intake or add a pinch of salt to your water.

Avoid intense workouts

On a balanced diet, your body uses glucose and glycogen stored in your muscles for a quick burst of energy. As glycogen stores are depleted, you may not have enough to fuel your training.

Research shows that ketogenic diets can inhibit performance by up to 20% during the initial phases of the diet. However, once your body adjusts to the ketogenic state, performance may improve.

Until your body adjusts, you may want to avoid vigorous workouts because they can put more stress on your body and cause headaches.

Plan meals that are low in carbohydrates and nutrients.

To maintain optimal health on a ketogenic diet, consider planning your meals ahead of time. This can help fuel your body to minimize unpleasant side effects when starting the keto diet.

Yes, the keto diet can lead to weight loss. But it’s hard to stick to, and you can limit your intake of many nutritious foods. That being said, many people don’t care about these things and can stick to a ketogenic diet for the rest of their lives.

It’s important to note that research shows that the ketogenic diet is no better than any other diet for weight loss. The initial loss may be higher, but in the long run it is not.

Finally, what I can say is that if you choose to go on a ketogenic diet, make sure you are ready to stick with it for the long haul. Also, understand that you don’t have to follow this particular diet to lose weight. A balanced diet can help you lose the weight you want in a healthier way.

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