If you are just getting started on the ketogenic diet and you are feeling dizzy when you stand up, generally tired or fatigued, irritable and on edge, nauseous, your stomach hurts, headache or you just can’t shake the sugar cravings you may be experiencing the dreaded Keto Flu.

The Low Carb Flu, Why Me?

Almost everyone feels it on some level when first getting started and some worse than others, but a virus like the traditional flu does not cause it. The “low carb flu” happens when you abruptly reduce or remove the high carb intake from your diet and move away from burning glucose (sugar) for energy to burning available fat to fuel your body.

Think about it for a moment. You’ve spent a lifetime eating lots of carbs and as you go through this short transition period of relying on glucose to relying on fat, but these symptoms will subside as your body adapts to this new way of eating.

Make sure to keep reading for our suggestions to combat the keto flu and make a smooth transition into ketosis.

Common Keto Flu Symptoms

Most people begin to feel symptoms of the keto flu within the first few days of restricting carbohydrates, and they usually subside within a week or so.

Of course, everyone is different, and it can be shorter or longer depending on many factors but here is a list of common symptoms in no particular order that you may encounter when first getting started on your path to ketosis and ultimately to your end goal of becoming fat adapted.

  • Confusion
  • Constipation
  • Cramping
  • Diarrhea
  • Dizziness or Light
  • Headed
  • Fatigue
  • Headaches
  • Heart Palpitations or Increased Heart
  • Rate
  • Insomnia
  • Irritability
  • Mental Fogginess
  • Muscle cramping
  • Muscle soreness
  • Nausea
  • Poor focus
  • Lack of
  • Concentration
  • Stomach pains
  • Sugar cravings

So, before you get discouraged after hearing about all these potential symptoms of the keto flu, let’s talk about how long you might feel some of these not so comfortable effects of adapting to keto.

How Long Does The Keto Flu Last?

The good news is it is brief and usually only lasts a few days to a few weeks at most. Trust me; it’s worth it once you get into ketosis and start to see the amazing effects the keto diet has on your mind, body, and life overall.

Depending on your lifestyle and how you’ve been eating before deciding to go keto, and your genetic makeup will impact how you experience the withdrawal symptoms from a high carb diet.

Someone who typically eats lots of fast food, processed foods and foods high in sugar are more than likely going to have increased keto flu symptoms when transitioning away from carbs than someone who is used to eating lower amounts of sugar and less high carb foods.

When we take into account the role genetics play and how some people are naturally much more metabolically flexible which means the capacity for the body to adapt fuel oxidation to fuel availability so that some people can make metabolic shifts more smoothly.

It’s clear that we all experience the symptoms and effects transitioning into ketosis differently, but whats happening on the inside of our bodies that contribute to the keto flu and our adverse reaction to reducing carbs.

What Else Causes the Keto Flu?

Several things contribute to the ketogenic flu including the loss of electrolytes and water along with the withdrawal from sugar.

Several studies and articles across the web discuss keto’s effect on the decrease in T3 thyroid hormone levels and the increase of cortisol levels which we won’t address here due to the depth that would be needed to cover those topics.

If you are interested in learning more about how hormones and the keto diet relate to one another, I suggest this article from Dr. Anthony Gustin as a great starting point.

Water and Electrolyte Imbalance

As we discussed in a recent blog post about electrolyte imbalances and their effects on how we feel, we also explained how your body loses stored electrolytes due to increased water, glycogen and electrolyte excretion as insulin levels naturally drop in the absence of carbohydrates.

This depletion of glycogen due to your body producing less insulin is what causes the significant water weight loss typically in the first week or two after going keto, and of course, the by-product of this is the loss of crucial electrolytes that our bodies need to function.

When we lose these key electrolytes like sodium and large amounts of water, it can cause an array of keto flu symptoms like dizziness, headaches, cramping, stomach aches, and nausea.

A great way to avoid feeling like this is to drink plenty of water and consume enough minerals in the food you eat or supplement to make up for the mineral loss.

But What About Things Like Energy Loss and Fatigue?

Fatigue is due to drastically reducing carbohydrates since glucose (sugar) storage easily provides a quick boost of energy when needed so without that glucose store it’s easy to feel more fatigued than usual.

Lets face it, we are all pretty addicted to sugar and its presence in almost everything we eat, whether that’s processed in things like soda or natural sugar in things like fruit.

So, if we make a massive reduction in the amounts of sugar and carbs we eat, we are going to feel the impact negatively at least initially.

Nonetheless, if you are considering jumping in feet first into keto or you are already feeling the adverse effects of the keto flu, here’s what you can do to prevent or reduce your symptoms.

Keto Flu Remedies and Prevention

Drink More Water and Stay Hydrated

Because you lose so much water at the beginning of the keto diet, you need to replenish lost water and rehydrate.

Dehydration and mineral loss is the most significant cause of the keto flu, but it can be quickly rectified by drinking more water. Anytime you are feeling nauseous, headaches or fatigued, grab a glass of water.

You can also add some unrefined salt to help replace some of the lost minerals.

Make sure to consume water throughout the day and monitor the color of your urine which is a good indicator of whether you are dehydrated or not. If your urine is bright yellow, you need water, and if it is clear, you are sufficiently hydrated.

KETO TIP: I like to mix a teaspoon of Pink Himalayan salt to my water a few times a week even after being fat adapted for quite some time.

Replenish Electrolytes

There are several ways to replenish your electrolytes. You can increase the amount of salt in your diet which is necessary due to the initial water and sodium loss while adapting to the ketogenic diet.

As mentioned my favorite way is to use Himalayan pink salt either mixed in water or added to my food.

Bone broth can also help, but honestly, it’s usually the salt in the bone broth that is doing the heavy lifting so buying expensive bone broth is not absolutely necessary in my opinion. However, If you love broth, drink up!

Consider eating foods high in potassium such as leafy greens like spinach or swiss-chard, nuts, avocados, clams, and wild-caught salmon.

You can also take an electrolyte supplement that contains magnesium, potassium, and calcium.

Eat More Fats and Calories

While on keto you need to consume more fat for fuel each day. The best way to replace the energy you used to get from carbs and sugar is with healthy fats.

What? Yes, that’s correct. Increasing your consumption of fats can assist in speeding up the transition from burning glucose to burning fat for fuel.

If you’re looking for healthy fats make sure to consider:

  • Avocados and
  • avocado oil
  • Butter
  • Coconut butter
  • Coconut oil
  • Cream
  • Egg yolks
  • Extra virgin olive oil
  • Fatty cuts of red meat
  • Fatty fish
  • Ghee
  • Lard
  • MCT oil
  • Macadamia nuts and macadamia nut oil
  • Fattier nuts, seeds and nut butter (ex. almond and macadamia nuts)

Speaking of MCT oil. Consuming MCTs (medium-chain triglycerides) positively alter your metabolism, are easily burned by the body for energy instead of being stored as fat which can assist ketone production during the keto flu.

Get Plenty of Sleep

Many experts suggest that adults need seven to nine hours of sleep each night. In the real world with family, work and other distractions, that can be tough to do.

Not getting enough rest can cause the stress hormone cortisol to increase, which can make symptoms of the keto flu worse and increase fatigue.

We all know its essential to sleep so try turning off your phone before you go to bed and make changes to your routine to get the rest you need to feel great!

Exercise and Relieve Stress

A great way to increase fat burning and get your body into ketosis faster is to exercise. You don’t need to run a marathon but get out and get moving.

Exercise will help reduce your stress, help you sleep better at night and ultimately help you avoid the keto flu symptoms by getting into ketosis and staying there.

Take An Exogenous Ketone Supplement

Although exogenous ketones are somewhat controversial and are not a replacement for the keto diet, they can help reduce the low carb flu symptoms.

Exogenous ketones add additional ketones to help it become more fat-adapted and enter ketosis more quickly. They can be helpful in preventing or even eliminating keto flu symptoms, boost energy and help fight fatigue by increasing the ketone levels in your system.

If you are interested in exogenous ketones, you can check our supplement recommendations.


Let’s Recap What We Learned About The Keto Flu and How To Cure It

  1. Why the keto flu happens due to transitioning away from carbs and sugar to burning fat for fuel.
  2. The common keto flu symptoms like headaches, fatigue, dizziness, stomach aches, nausea, cramping, and soreness.
  3. The keto flu is temporary and typically lasts a few days to a few weeks at most.
  4. Loss of water and electrolytes contributes to the keto flu.
  5. How to fight off the low carb flu by drinking more water, replacing lost electrolytes, eating more fats, getting plenty of sleep, exercising, relieving stress and considering exogenous ketone supplmentation.

If you want to steer clear of the keto flu or reduce the symptoms make sure to use the tips we’ve suggested above. This will help you make the transition into ketosis and well on your way to the full benefits of the keto diet once you are fat adapted.

If you are new to keto or just want to get a more in depth overview of the ketogenic diet make sure to read our comprehensive Keto Diet Guide.

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