When some people begin their journey towards a ketogenic diet, they experience something called the ‘keto flu’. This typically is experienced within the first 7-14 days on the keto diet.

Switching your body from metabolizing glucose to metabolizing fats can be a shock to your system. This is especially true within the few first days of adopting the keto diet. This transitional period and resulting side effects, termed the �keto flu,� because some of the symptoms feel the same as catching a cold or flu. typically begin within 24-48 hours of starting the keto diet plan and last about 3-7 days.

What causes the Keto Flu?

These flu-like symptoms occur due to your body’s natural process of protecting itself during what it recognizes as carbohydrate starvation. As carbohydrate and blood sugar levels decrease, insulin decreases and insulin sensitivity increases.

As blood sugar levels go down, our body signals to our kidneys to release electrolytes (sodium, magnesium, and potassium), carrying with them water. This often causes dehydration.

As our bodies go into carbohydrate starvation mode, they also upregulate cortisol (stress hormone) levels in an attempt to increase energy levels.

What are the symptoms of the Keto Flu?

If you think you are experiencing the keto flu here are a few common symptoms:

• Headaches
• Fatigue
• Mental fogginess
• Muscle cramps
• Lower strength and stamina
• Digestive issues
• Constipation
• Insomnia
• Sugar cravings

How to Beat the Keto Flu

It’s important to know that the keto flu symptoms are a sign that your body is in the process of making the proper metabolic adaptations.

All of these are normal when switching to the keto diet and as your body becomes adapted to using fats and ketones as a main source of fuel, they will subside.

But in the meantime, while you are suffering from the keto flu, here are a few strategies to combat the symptoms.

Drink lots of water

You should increase your fluid intake to replace the water lost in the first few weeks of keto. This means consuming about 10-12 glasses per day. As a rule, drink a glass of water for every hour you are awak during the day.

Replenish electrolytes: sodium, magnesium, potassium

Make sure to increase your sodium levels for the first 14 days. How much? Divide your body weight in pounds by two and that is roughly how many ounces of sodium you will need per day (around 5,000- 7,000 mg/day). Add sodium to your diet by adding more unrefined salts (Himalayan pink salt or sea salt are the best) to water or foods, drinking salted lemon water, or drinking bone broth. You should also get roughly 1,000-3,500 mg of potassium per day.

Potassium is found in foods such as fish, meat, leafy greens, and winter squash. Magnesium is another electrolyte you should increase intake of, taking about 300-500 mg per day. You can find magnesium in foods like spinach, chicken, beef, fish. All of the above electrolytes can be taken in supplemental form if you cannot get proper amounts from your daily diet.

Moderately exercise, practice yoga or meditate

Exercise can help balance out the increase in cortisol levels during the keto flu. Moderate exercise is suggested so as not to put more stress on your body than the metabolic shift it is already dealing with. If moderate exercise is too much, especially with the possibility of other symptoms, consider practicing yoga or other forms of meditation to reduce cortisol levels during the first transitional weeks of adopting the keto diet.

Eat more fats and calories

Yes, that’s right: more fats! Increasing fats can help surpass the keto flu growing pains and increase energy levels. A great way to add fats during these transition periods is with MCT oil because it goes straight to the liver after digestion. Other ways include things like adding coconut oil to your morning coffee, eating grass-fed jerky, or even eggs. You can also increase ketones with exogenous ketone supplementation at smaller doses, spread throughout the day, for the first 3-5 days of keto.

Reduce your carb intake slowly

Instead of dropping straight to the goal mark for daily carbohydrate intake (i.e. below 20g per day), it may be helpful to slowly decrease carbohydrate intake and in a sense prevent the shock� of the keto flu.

For example, if you generally eat 140 g of carbohydrate per day, it may be useful to cut back by increments of 20 g a day (or every other day) for the first week (or two) of starting keto (day 1= 140 g, day 2= 120 g� day 6= 40 g, day 7= 20 g). You can read our full guide to your first seven days on keto here.

Remember that it’s short-lived

Maybe most important is to remember that all these symptoms will pass, and you will feel much better soon. Don�t let these temporary keto flu symptoms scare you away from continuing your keto journey and acheiving a healthier lifestyle!

- Dr. Jerry Hizon, MD