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Keto Flu and How To Avoid It

Although the name may suggest it, the “keto flu” is not a real illness and it has nothing to do with the regular flu. The only reason for the name is perhaps the way you may feel while your body transitions from using glucose as a source of energy to using fat and ketones. This is a result of reducing your carbohydrate intake significantly.

What Is Keto Flu?

The keto flu is your body’s response to utilizing fats to produce ketones. This process confuses your body, hence why you may be feeling less than yourself during the time you are entering ketosis. Here, you are basically feeling carbohydrate “withdrawals”.

It is also important to note that keto flu is not a phenomenon you will read about in research papers or medical journals. You will most likely hear about it from other people on the ketogenic diet and through social media. However, these symptoms are not imaginary and they occur quite often as a result of reducing your carbohydrate intake significantly.

Unfortunately, a lot of people do not know how to deal with the symptoms of the keto flu, which may prompt them to stop the diet altogether before they can reap the benefits. Despite these keto symptoms which may range from mild to moderate, it is worth to be patient – the list of benefits of the ketogenic diet is long and promising.

What Causes Keto Flu?

There are several reasons for this less-than-desirable side effect of the ketogenic diet. Here, your body transitions from using carbohydrates as a source of energy in favor of using fat to produce ketone bodies. At this time, there is also a decrease in insulin levels which causes your kidneys to work overtime. This is why you may also urinate more frequently than usual, among other side effects.

Some additional reasons for keto flu may include temporary low blood glucose caused by limiting your sugar and carbohydrate intake, as well as mineral deficiencies and changes in electrolyte balance. Thankfully, these effects do not last long. For most people who are just starting the ketogenic diet, such effects will only last about a week.

You may also notice a spectrum of digestive issues, such as constipation or diarrhea which are predominantly caused by your body adjusting to eating nutritious, low-carbohydrate foods. In order to alleviate these symptoms, make sure you are eating enough fiber in your diet. A good source of fiber is available in avocados, chia seeds, flax seeds, pumpkin seeds, leafy greens and cruciferous vegetables among others. To read a full list of keto-approved foods, click here.

What Are The Symptoms Of Keto Flu?

It is not easy for your body to switch from using glucose as energy, to using fat and ketones.

There are many health benefits of the ketogenic diet, including research-backed, positive effects for some medical conditions. However, all of these advantages do not come without some discomfort.

Symptoms of keto flu may include:

● Headaches
● Migraines
● Constipation
● Diarrhea
● muscle pains
● Cramps
● Abdominal Pains
● Fatigue
● Bad Breath
● Food cravings
● Sleep Disorders
● Irritability
● Mood Swings
● Poor Concentration
● Brain Fog

How Long Does Keto Flu Last?

Usually, the onset of the keto flu begins about 24-48 hours after carbohydrate restriction. For most people, keto flu lasts up to a week, however, there are very rare cases where ketogenic diet beginners have to battle these unwanted symptoms for even up to a month.

It all depends on several factors, such as genetics – some people who transition to keto have never experienced the keto flu at all. Still, this all depends on your metabolic flexibility and how fast your body is able to switch and adapt to new metabolic states.

How To Get Rid Of Keto Flu?

Most of the time, keto flu symptoms disappear within a week. However, some people take a little longer to switch their metabolism to using fat as the primary source of energy, instead of glucose.


Staying hydrated is the cornerstone of the ketogenic diet. This is important especially in the beginning of you ketogenic journey, because loss of minerals during the adaptation phase is not uncommon.

If drinking lots of liquids is difficult for you, try to have a bottle of water nearby: on your desk or on your kitchen counter where you can see it. If you do not like the taste of water by itself, it may help to add some freshly-squeezed lemon juice for an extra boost to your metabolism.

Although lemon is a fruit and people may think it is not recommended on a ketogenic diet, the juice of one lemon is just 3 net carbs. During the ketogenic diet, it is recommended to begin by eating between 20-50g net carbs daily, thus 3 net carbs is just a small percentage.

In addition, drinking lemon water is known to remove toxins from your body and decrease the amount of uric acid, which is known to be a contributing factor in gout and kidney stones. And on top of everything, unprocessed, fresh lemon juice has plenty of vitamin C!

2. Increase your salt intake

Well, what do you mean “increase salt”? Isn’t salt the root of all problems?

Actually, it is not.

You may have heard that salt increases your blood pressure, which can potentially lead to heart disease, strokes, heart attacks and kidney stones. However, studies have shown that consuming less salt and implementing low-sodium diets in patients with normal blood pressure shows no significant difference on their cardiovascular health [*].

Lots of processed foods have a high level of sodium, therefore on the ketogenic diet, where you do not eat modified foods you may actually need more salt than you think is necessary. Sodium is the most concentrated electrolyte in our bodies and is responsible for muscle contraction, conducting nerve impulses and maintaining blood pressure.

If there is too much sodium in our bodies, our brain will prompt us to drink more water so we can later excrete the excess sodium in urine. Particularly in the beginning of your ketogenic diet, your sodium needs increase – especially due to your kidneys getting used to handling salt differently than before.

Since hydration is a very important aspect of reducing keto flu symptoms, you may want to add salt to your water. If that doesn’t sound like something you would want to do, add an extra pinch of salt to broth, salad or supplement with electrolytes.

Why should I supplement my diet with electrolytes?

Electrolytes are a powerful supplement, especially during the keto flu. During this time, you are introducing a new metabolic state to your body, which may not be ready for this change without causing a revolution. It is very important to hydrate yourself and remember to replenish electrolytes.

Every gram of glucose bounds three grams of water. If you are reducing your sugar intake, you body will be flushing out excess water – which is a reason for frequent trips to the bathroom during keto flu. Because of this, you will also be losing important minerals, for example, electrolytes that include magnesium, calcium, potassium and sodium.

Without electrolytes, your body would not be able to function properly. They are responsible for body temperature, muscle contractions, your heartbeat and other neurological functions. It is advisable to supplement with store-bought electrolytes which can easily restore lost minerals during keto flu, and relieve unwanted symptoms.

3. Eat more fat

Yes, consuming more fat means consuming more calories. One gram of fat has 9 kcal, as opposed to carbohydrates and protein which have 4 kcal per one gram.

However, in the beginning of your ketogenic journey it is not recommended to cut down on your calories, even if your goals are to reduce body mass. The first week of the ketogenic diet is one of the most difficult times for your body – this is when you are learning how to use fat and ketones for energy instead of glucose. Therefore, it is only logical to consume more healthy fats and help your body adjust to this metabolic switch faster.

In order to increase your fat intake, remember to consume healthy fats which you can find in foods like avocados, nuts, chia seeds, fatty fish, flaxseed oil, coconut oil and MCT oil. Even drizzling an extra tablespoon or two of flaxseed oil on your salad will increase your fat intake significantly. If you are worried about calories and your primary goal is to shed some pounds, it will be much easier to reduce your caloric intake once your body becomes fat adapted.

4. Do light exercises

During your transition phase, you may be feeling some or all of the symptoms of the keto flu, such as headaches, muscle weakness, cramps and tiredness. This is not the time to perform strenuous activities.

By switching metabolic states, you are already putting a burden on your body and any additional, exercise-related stress is not recommended. Most athletes who switch to the ketogenic lifestyle report a decline in their performance levels within the first month.

While it is not recommended to do any medium to high levels of exercise, doing low-activity cardio, such as yoga, pilates or even briskly walking around your neighborhood may relieve some of the keto flu symptoms including muscle tension and overall body pains.

5. Reduce carbohydrates gradually

There are three most common approaches to achieving ketosis and getting your body to produce ketones.

You can either:

  • Start Off With A Fast
  • Suddenly Reduce Your Carbohydrate Intake
  • Decrease Your Consumption Of Carbohydrates Gradually

Each of these methods has their advantages, however, slowly lowering your carb intake may be the best option for those who want to significantly diminish or even avoid symptoms of the keto flu. Instead of cutting out carbs rapidly, you may want to take a week or even a month eating low-carb.

The initial shock of the ketogenic diet has a lot to do with eliminating sugars and processed foods. For example, try reducing your carbohydrate intake by 20g of carbs per day. It is not a significant number, however, within a few days you will find that you are not that far away from the designated 20-50g net carbs allowed on the ketogenic diet.

If you are already on the ketogenic diet for a week or two and have not experienced any of these symptoms, congratulations! Not everyone will experience them, and if they do, the above mentioned symptoms may be so mild that you may not even notice them.

For others, however, it is important to be aware that your transition period may be less than desirable. If this is the case and you are slowly beginning to feel the side effects of the keto flu, listen to your own body, read about the experiences of others and keep our tips in mind.

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