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Your Definitive Guide to Conquering the Keto Flu

By: Bulletproof Staff

Your Definitive Guide to Conquering the Keto Flu
  • The keto flu is your body’s natural response to carbohydrate restriction.
  • Its symptoms include: brain fog, headache, chills, sore throat, digestive issues, dizziness, insomnia, irritability, and more.
  • Symptoms typically last from a few days to two weeks, and up to a month at most.
  • Metabolic flexibility, meaning your ability to adapt to different fuel sources (sans uncomfortable symptoms), dictates the severity of symptoms.
  • Keto flu remedies include: proper hydration; bone broth; electrolytes like potassium, magnesium, and sodium; eating more good fat like MCTs; rest and sleep; mild exercise or meditation; activated charcoal; exogenous ketone supplements; and in some cases, eating more carbs.

You started the keto diet and are just not feeling it. Instead of all those amazing ketogenic benefits you’ve heard about – supreme fat burn, increased energy, keto clarity, and a vibrant sense of well-being – you are irritable at the breakfast table, dizzy all day, and not sleeping at night. The culprit of this miserable feeling? Oh, right: the keto flu. It’s a natural reaction your body undergoes as it switches from burning sugar to fat for energy. In order to get from here to there, your body needs to make a few modifications to the way it runs. Read on to learn what’s in store as you rev up your internal engine, keto-style.

What is the keto flu?

Barebones – the keto flu is your body’s natural response to carbohydrate restriction. If you’ve embarked on the keto path, you likely know that a keto diet – high in fat, moderate in protein, and low in carbs – implies you burn fatty acids for energy instead of glucose, which comes from sugar and other carbohydrates. While fat is typically a backup fuel source, you will tap into it if there is insufficient glucose, your body’s preferred fuel, from your diet. The metabolic state of ketosis is a fancy word for burning fat rather than carbs, and it is the secret weight-loss weapon to the keto diet.

What are the symptoms of keto flu?

  • Brain fog
  • Headache
  • Chills
  • Sore throat
  • Confusion
  • Dizziness
  • Insomnia
  • Irritability
  • Muscle soreness
  • Nausea
  • Poor focus
  • Stomach pains
  • Sugar cravings

How long does the keto flu last?

The keto flu, aka carb withdrawal, generally kicks in at the 24- to 48-hour mark. Symptoms typically last from a few days to two weeks, and up to a month at most. Whether you experience its symptoms – and to what extent – depends upon your metabolic flexibility, meaning your ability to adapt to different fuel sources (sans uncomfortable symptoms).

Metabolic flexibility is influenced by genetics as well as lifestyle habits. For instance, how you ate prior to going keto may predict the severity your flu symptoms. If you ate a diet low in refined sugar and starches, you’ll likely experience only mild symptoms. A diet high in sugar and carbs may set you up for greater withdrawal symptoms (especially from the sugar).

What causes the keto flu?

What exactly causes keto flu symptoms? When you restrict carbohydrates, your body must learn how to burn its backup energy source, and in order to do so, changes happen from the cellular to hormonal level.

Specifically, there are three changes that occur when you cut out carbs:

Water and sodium flush:  When you consume fewer carbs, insulin levels drop – signaling your kidneys to release sodium from the body. This causes a loss of up to about 10 pounds of water weight as water shuttles sodium out of your body. All of this usually occurs in the first five days. The glycogen loss and low insulin levels cause dizziness, nausea, muscle cramping, headaches, and gastrointestinal issues, like diarrhea and constipation. Do your best to drink plenty of fluids and electrolytes at this point (more on this later) – that’ll alleviate some of these cellular symptoms.

T3 thyroid hormone levels may decrease: T3 is a hormone produced by the thyroid gland. Dietary carbohydrates and thyroid function are closely connected, so when you cut carbs, T3 levels can fall. In conjunction with T4, another thyroid hormone, the two T’s regulate your body’s temperature, metabolism, and heart rate. As your body adjusts to a ketogenic diet, lower hormone levels may leave you with brain fog and fatigue.

Increased cortisol levels: The T3 hormonal change is closely connected to a third hormonal change – higher cortisol levels. A ketogenic diet tells your body that you’re in starvation mode. In an effort to increase energy levels on a carb-restricted diet, your body triggers the release of stress hormones, i.e. cortisol. If you experience irritability and insomnia, that’s a clue that your cortisol levels have jumped. Not to worry: as you adjust to utilizing fat and ketones as a new fuel source, your cortisol levels should fall to their old levels.  

7 keto flu remedies

Take heart: if you’re experiencing any discomfort, there are things you can do to minimize your unease and conquer the keto flu. Elevated energy and optimal performance are just on the other side of those symptoms. You got this.

Hydrate all day. Water reigns supreme when it comes to kicking the keto flu, especially if you add some unrefined salt. How much should you drink? To determine the minimum amount you need, use your current body weight and divide it by two. That’s how many ounces you need. For instance, if you weigh 140 pounds, you should aim for 70 ounces of water a day.

Drink bone broth. Any water you can sneak into your diet is a great step to set you up for keto rebound. Bone broth adds a serving of water to your diet and a dose of electrolytes – sodium and potassium – which will offset some of the discomfort you feel at a cellular level. Get our bone broth recipe here.

Supplement with electrolytes. Replenishing your electrolytes is a great way to start feeling better fast. Take note of the key players – potassium, magnesium, and sodium. If you aren’t getting enough of them from your diet, which can be difficult to do on low-carb, incorporate them by-way of supplements.

  • Potassium: Eat fish, meat, leafy greens, winter squash or supplement with 1,000-3,500 mg per day. If you are battling cramps, constipation, or muscle weakness, go for potassium.
  • Magnesium: Eat spinach, chicken, beef, fish or supplement with 300-500 mg per day. Magnesium helps with keto flu symptoms like muscle cramps, dizziness, and fatigue.
  • Sodium: Particularly important if you are exercising or live in a hot climate, supplement with 5,000-7,000 mg per day. Cramping is alleviated with proper sodium intake

Eat more fat especially MCTs. Upping your fat consumption can speed up your adaptation phase – you’ll start to burn fat instead of glucose more quickly. There is one issue, though. Most fats have to pass through your lymphatic system to your heart, muscles and fat cells before they reach the liver. Only there can they be turned into ketones for the body to use as fuel. MCT oil is different in that it goes straight to the liver after digestion – just like carbs – so they can be used immediately. Supplementing with MCT oil may even help you avoid keto flu altogether. Other easy ways to ramp up the fat: Add coconut oil to your morning brew, try grass-fed jerky or eggs as a snack, and check out some of these recipes to tap the fat.

Get good rest. A sound night’s sleep is a very good thing when it comes to conquering keto flu. It keeps your cortisol levels in check, which will likely lessen your flu symptoms. Aim for 7-9 hours a night, and try these sleep hacks to reach for better zzz’s.

Exercise (mildly) and meditate. Did you note the second word – mild. Yes, mild. The goal here is to reduce cortisol levels (especially initially), so anything that relieves stress will help you. Yoga or gentle walks can do the trick. If exercise isn’t your thing, try meditating. Bottom line, it’s probably best not to go full-on in the gym until you adjust to the keto diet.

Take activated charcoal. Activated charcoal works to detox your body of any toxins. Charcoal binds to chemicals whose molecules have positive charges, including many toxic molds[1], BPA[2], and pesticides[3]. As you adapt to burning fat for fuel, you’ll shed extra body fat. Toxins are stored in this fat, so the charcoal assists to swiftly usher these out the door and optimize your general sense of well-being.

Take an exogenous ketone supplement. Exogenous ketones aid with fatigue and boost energy levels by raising the ketone levels in your blood. Note that they are not a replacement for a proper keto diet, though they may help you take it up a notch – especially on the flu. If you choose to go this route, aim for smaller doses of your supplement – spread throughout the day, for the first 3-5 days of the keto flu.

If all else fails, up your carb intake. For some people, increasing fat simply won’t curb keto flu symptoms. If this is the case – and you tested your limits by adding more fat and are still experiencing flu-like symptoms – you’ll want to up your carb intake just a bit. This carb refeeding time goes a long way to ensure you feel better – as it gives your body the chance to adjust to burning fat, because it has some glucose (carbs) to utilize as you adjust.

keto flu remedies

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