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Beating the Keto Flu

Beating the Keto Flu

The keto flu explainedKeto flu causeWhat to doUseful knowledge

The keto flu is for lack of a better word, vexed. That is: difficult, problematic and much debated [1].

Typically, the way you first come across the keto flu isn’t convenient either. It remains hidden in the bushes until you take your first steps on the ketogenic journey. Everything seems dandy and you’ve eaten the correct ‘keto foods’ but once your blood sugar lowers, it strikes.

This places you in a tough spot. Do you give in completely and quit, retreat to a standard diet and regroup, or do you problem solve your way through this headstrong?

In this guide we will provide you with the information necessary to make that decision for yourself.

So what is the keto flu?

Anecdotal definition: "the keto flu is a symptomatically flu-like condition observed while the body newly transitions into a fat adapted state." – Team Keto.

The Keto Flu Explained

When was the last time you were hungry? Not just bored hungry, but really, truly hungry to the core? How long did this persist until you loaded up on carbohydrates?

If you’re like us when we first started out – the answer is not long at all. We overfed our bodies to the point that using carbs is all our metabolism has had to worry about for years on end.

Metabolize fat, why? There has not been a need. This sets us up for a tough time entering ketosis.

When the keto flu hits…

It’s a very cruel awakening the day that you cut carbohydrates. To your body, this is unexpected and it’s not ready for it. For awhile the metabolic gears go into low-energy mode waiting for its precious overdue carbs.

When that doesn’t happen for long enough, when you finally get hungry enough, a change in your body begins to take place. You begin to become fat adapted like you are meant to be. Meaning, your body is capable of switching to fat for energy in a minimally debilitating way.

But even after your body acknowledges the need to make the shift, it takes time to completely get it right. And until it does, you’re still in the thick of the keto flu.

Keto Flu Symptoms:

Think you are experiencing the keto flu? Here’s the symptoms list:

  1. Difficulty concentrating – your brain power just isn’t there.
  2. Lethargic fatigue – you really just want to take it easy and hard tasks are daunting.
  3. Headache / Dizziness – the truest ‘flu’ symptom, feeling burnt out.
  4. Extreme food cravings – even if you’ve eaten keto-friendly meals, you're voraciously hungry for the wrong things.
  5. Trouble sleeping – your body just can’t settle down, maybe you are having hot/cold flashes.
  6. General state of bitterness – you’re grumpy and good luck to anyone around you.

    What’s happening internally during the keto flu?

    All of the keto flu symptoms stem from a lack of metabolic flexibility, and likely obesity in general stems from this, 'metabolic inflexibility' [2]. Metabolic flexibility is your body's ability to switch between energy sources like carbs and fats [3, 4].

    Think of metabolic flexibility as how sensitive your body is to switching energy sources. Switching energy sources can be caused by hunger, exercise needs, or even a leptin-based response from over-feeding. The problem is that over time without proper stimulus (hunger or exercise) the body becomes less sensitive or 'flexible' to those very stimuli. The negative effect we notice from this is an inability to burn growing fat deposits [5].

    Upon starting the ketogenic diet, we FORCE our body to participate in metabolic flexibility and switch to fat metabolism. The 'keto flu', is partly the challenge in giving it enough stimulus to break through its insensitivity and make the switch.

    Teaching your body metabolic flexibility

    When you begin the ketogenic diet, you are teaching your body to regain metabolic flexibility in order for your metabolism to become fat adapted. Here is what happens:

    1. You stop eating carbohydrates.
    2. Your body depletes carbohydrates and glycogen over 2-7 days, but you can begin to feel lethargic as soon as the first 12 hours.
    3. As carbohydrate reserves drop, so do insulin and electrolyte levels. Insulin dropping is positive for fat metabolism, but electrolyte loss will intensify symptoms.
    4. Your brain is hungry, and your body double-commits to the ketogenic shift in order to feed it.
    5. Over the course of days, your body increases the enzymes necessary to break down fats. As well, metabolism hormones become less resistant (a good thing).
    6. Your body is able to get the energy it needs from fats, but hunger and satiety problems may still remain in those with leptin resistance.
    7. Eventually, you’ll be a keto warrior. That means, you’re able to manage a fat-based diet and your body has adjusted too. Translation: less cravings, more energy, and overall success.

      What we left out from this 7-step keto flu process, is how crappy you’re likely to feel during it (aka ‘keto flu symptoms’ list above. So yes, if you are having a difficult time, know that its not your fault, you’re probably doing everything right… Its just a challenging process setting your body straight.

      How to transition into keto while minimizing the keto flu

      We know what the keto flu is and what happens in our body to make us feel this way. So, how can we best glide into the ketogenic diet while avoiding as much of the keto flu as possible?

      There are two strategies to consider:

      1. Transition into a low (lower) carb diet and then transition to keto.
      2. Jump directly into keto using a free 15-day Keto Kickstart Program.

      If you have been extremely reliant on carbs, can’t exercise the same way as when you were younger, or overall have a very long way to go and are afraid of failing… Then you may want to ease into the keto diet. You will do this by progressively reducing your carbohydrate intake over time until you’ve weaned off, and then go full keto.

      Once you begin keto, here is our advice...


      From keto flu to ketosis success checklist:

      1. Choose or design a meal plan. Our new keto warriors use the 15-day Keto Kickstart Challenge. Its completely free and you can use it too for meal plans, grocery lists, workout routines, etc.
      2. Plan your schedule accordingly. You know that the next week is going to be your toughest. If you have some days available to take off work, or can begin the keto diet on a Friday – do it.
      3. Adjust your exercise for lighter work. Light intensity exercise like brisk walking and calisthenics naturally stimulates fat metabolism for energy [6]. This is good, and can increase the grace and speed towards ketosis. Heavy lifting on the other-hand can be too much.
      4. Increase your water and electrolyte intake. As your glycogen and insulin drops, you will be releasing tons of stored water and electrolytes. This can be up to 10 lbs, that you will rapidly release in the first week or so. This quick shift towards dehydration can attribute to the keto flu symptoms, be prepared to drink a lot of water and salt your food with Himalayan sea salt for electrolytes while your body balances out.
      5. Prioritize sleep. While the keto flu makes most people feel completely exhausted, come nighttime falling asleep may be tougher than expected. To help, head to bed 30 to 60 minutes earlier than normal. This will give you the greatest chance at falling asleep before you miss your natural sleep window.
      6. Have exogenous ketones available for quick energy. This is optional, but comes in handy. Exogenous ketones are the supplemental form of ketones that your body makes for energy. If at any time during the keto flu you need a safe way to rapidly boost mental acuity and energy – exogenous ketones are the solution. A side benefit to exogenous ketones is that they provide a big electrolyte kick.

        The ketogenic diet doesn’t have to be difficult. However, if you slack on your diet preparation, don’t drink enough water, or miss out on too much sleep – its going to be a serious challenge for you.

        Luckily over time if you stay consistent or gradually improve, your bodies metabolic processes will shift in your favor. Once you get there, you’re not going to want to go back!

        The bottom line

        The keto flu is real, but it doesn’t need to be ‘the worst thing ever’. There are several steps that you can take to get into ketosis easier, and the reoccurring theme is that you really need to just plan in advance and stick with it.

        Summary of what we’ve learned:

        1. The keto flu is the discomfort experienced from a low-energy state while the body hormonally and enzymatically adapts to a fat fueled diet.
        2. The symptoms of the keto flu include: difficulty concentrating, lethargy/fatigue, headache/dizziness, food cravings, trouble sleeping, and unpleasant mood.
        3. During the keto flu: your body depletes significant stores of glucose, glycogen, and electrolytes. Eventually insulin drops, and the gears are set in motion for fat metabolism to produce brain and body fueling ketones.
        4. You can wean yourself off carbs slowly to reduce and spread out the keto flu or you can dive straight into the ketogenic diet and face it head on.
        5. Your checklist to avoid the keto flu should contain: a full meal plan made in advance, wise timing in your professional schedule to begin the diet, lighter exercise, increased water and electrolyte intake, prioritized sleep, and exogenous ketone supplements.
        6. Within a week or two, your energy needs will be met through fat metabolism and things will get easier. But until then, you’ll be glad for all of the preparatory work you did in advance.

        Additional information

        Here are some additional points that we found interesting.

        Leptin and leptin resistance

        Leptin is the hunger / satiety hormone [7]. It’s produced naturally by fat cells to signal to the brain that you have enough fat stored and more food isn’t required. Leptin resistance occurs when over time you keep over eating and over eating, causing the brain to ignore the leptin ‘stop eating’ effect. However what sucks, is that the reverse effect of leptin, creating hunger, will be in vicious effect as your fat cells begin to get broken down and leptin levels decrease… This may make your initial few weeks of keto extra difficult.

        Diabetes type 1 and 2

        If you have diabetes or are pre-diabetic, the keto and low carb diet may be able to help with both insulin and weight loss - but you will need doctor supervision. Without direct medical supervision there are serious risks involved.

        Releasing toxins from fat

        Some people use the ketogenic diet specifically to detox. Kourtney Kardashian recently did this on a mercury detox, and exclaimed to have liked the process and results [8]. In some circles, the release of stored toxins in fat cells is believed to be part of the keto flu pain.

        Carbohydrate withdrawal

        Apparently, the system that releases dopamine (feel good hormone) in response to sugar is quite similar to the one that releases dopamine in response to cocaine. This has led many keto companies to compare carbohydrate withdrawal to that of drug withdrawal. We’re on the fence about this, however its interesting to know.

        Change in breath smell

        As your body produces more ketones, you may notice a change in your breath. This is a mind possible side effect, and apparently smells a bit like acetone to those that get it.

        Acute and Intermittent fasting

        Intermittent fasting refers to a feeding technique where you restrict your eating periods. A good example would be only eating food between 11 am and 7 pm. By doing this, you are ‘feeding’ from 11 am to 7 pm (8 hours), and fasting from 7 pm to 11 am (16 hours). Doing so can increase the amount of fat you burn, even if you eat the same amount of food per day, due to insulin getting even lower, triggering a greater fat metabolism response during the 16-hour fast period.

        Electrolytes and hydration

        During the keto flu you’re going to lose a ton of water as carbs leave your body. Many experts recommend seeking out electrolyte sources to help you feel significantly better.

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        • Hi Eileen! It sounds like something may be a little off in your keto diet. You should not be feeling that way after that long. Please email us more information so we can assist –

        • I’ve been dieting for 30 days, down 10 pounds. Why am I feeling so bad, severe fatigue and headaches almost to the point of going to urgent care. Drinking 3 to 5 liters of water a day.

          Eileen Barker
        • Hi Elizabeth! Yes we have a recipe under our recipe section!


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