The popularity of the ketogenic diet has brought with it increased exposure of the side effects and other important information that needs to be considered when cutting carbs out of your diet. While carb restriction and its associated benefits have gained widespread attention – so have its associated downsides.
The “Keto flu” is one of the most controversial and misunderstood aspects of the keto diet, and the misunderstandings are obvious from a quick look around the internet. People who are looking to make a quick buck from the popularity of keto have got plenty to say about the topic. Unfortunately, they also have very little science to back it up.
Today, we’ll take you through the real causes, symptoms, and solutions to the keto flu. We’ll discuss everything you need to know, so you can make informed choices about your diet and stay in control of your body.
Key Facts About Keto
The first thing to keep in mind about keto is that it begins and ends with carb restriction. When you eat fewer carbs, your body processes adapt to become more efficient at processing body fat and dietary fats for fuel. Thus, you don’t need to depend on carbs anymore. This will be key, as it plays a large role in everything about your diet from the moment you start nutritional ketosis.
Ketosis is the crucial process for the ketogenic diet. It’s what happens when your body is out of carb-fuel, either because you’re using a lot (exercise-induced ketosis) or because you’re not filling up carb stores with your diet (nutritional ketosis).
This state of metabolism is unique and, for most 21st-century dieters, very unfamiliar. With a typical carb-heavy diet, we’ve got a long way to go to get back to ketosis, and it can be both daunting and a little lengthy. With a typical keto-adaptation period of around 3 months, your body will slowly keep getting better at using fats after you start the keto diet.
There are also some “traditional” keto foods that we might consider important. For example, when you switch to the ketogenic diet, you’ll probably rely primarily on lean meats and veggies – a great pairing but not a complete diet. This often impacts the way your body responds and can be linked directly to the severity of the keto flu and how you can combat it.
Finally, it’s important to remember that the very point of keto – and the method by which it works – is a mild restriction state. This means that you’ll be existing in a state of mild calorie restriction – something that plays into the way you’re feeling and your performance in the gym, on the track, or wherever else you work out.
These are just a few key points to keep in mind, and the science behind them will determine how you come out when you finally pull the carbs out of your diet and go full-on keto.
What is Keto Flu?
This is the big question you’re here for: both in terms of symptoms and causes!
The symptoms of keto flu are how we recognize and diagnose it. They begin with feelings of lethargy and fatigue despite sufficient sleep and other normal lifestyle behaviors, but they can stretch all the way to feelings of dizziness and poor mood.
Right away, we’ll remind you that any severe or worsening symptoms should be treated by a doctor. If you feel a bit under the weather, it’s keto flu. But if you’re feeling dizzy all the time or you’re worsening after a week, then it’s progress into a medical concern. Keto isn’t for everyone, and if your body respond poorly, then it’s time to chat with your physician.
Keto flu is characterized by a set of common symptoms. These include:
- Bad breath
- Reduced exercise performance
- Decreased power output
- Muscle weakness or cramping
Your individual response may differ, however: the changes you experience are based on your individual needs and what you eat. You may not even experience keto flu. However, it’s always better to be safe than sorry, and understanding the symptoms will help you understand a ketogenic diet better.
Why Does this Happen?
To start, you’re probably taking in fewer carbs and less salt, which means you’ll be heading toward dehydration during the early days of keto. This is the direct result of low carbohydrate and sodium intake, meaning two things: your body won’t retain as much water, and thus you’ll be visiting the bathroom more often.
The keto diet is a mild diuretic, meaning that you’ll be peeing far more often, so you can easily run out of water if you’re not actively hydrating yourself. When you’re in the first few weeks of keto, be sure to monitor your water intake and keep it high at all times to prevent dehydration.
Second, you’re not very good at processing fats for fuel if you’ve lived on a carbohydrate-rich diet for the last few decades. This can mean that cutting them out of your diet is one of the most taxing things you can do in the short-term. This isn’t a problem once you adapt, but for the first week or two, it can be pretty rough.
Once you adapt, you probably won’t run into many problems. But to start, you’ll be carb-depleted and on a calorie-deficit diet, which can negatively affect mood and cognitive performance in the short-term. Between these two changes, it’s not hard to see why you might be feeling tired and weak – you are. We’ll talk about how to manage these symptoms a little later.
Finally, remember that this is change – something your body deals with in a slightly-lagged timeframe. Changes you make to your diet now will affect your body in the short-term but after a little delay. This change is nothing to fear as long as you’re not running into serious medical problems – once that timeframe has passed, you probably won’t run into this problem again!
Avoiding Keto Flu (Step One): Don’t Go Cold Turkey
No, we’re not talking about sandwich meat. Definitely eat turkey. 😊
Going cold turkey from carbs is something we see often but trips up a lot of new keto dieters. The reality is that your body doesn’t see your diet in black and white terms: increasing your fat intake and reducing carbs is a step toward keto-adaptation, even if you’re not cutting out carbs entirely.
If you’ve been eating a high-carb diet for years, the best choice for your first keto diet is probably a mild cut in carbs and an increase in high-quality fats. You can cut down on carbs slowly over the space of 2-4 weeks, rather than jumping into the deep end of the keto pool. This reduces the chance of nausea, diarrhea, dehydration, and especially headaches/migraines.
These happen due to a rapid reduction in carbs, leading to dehydration and a poor energy balance in the brain (which relies on carbs). Balancing this out allows you to gradually get better at metabolizing fats without requiring your body to adapt straight away. This can mean fewer side effects and a more enjoyable, but longer, transition to full keto.
Gradual adaptation is how your body works. You can’t expect a change in diet this huge to take place overnight. It’s part of a smarter approach to keto: avoid the problems of hydration and discomfort rather than just using fat burning as an excuse to sabotage your health. Remember: keto is a gradual lifestyle change – you need to address problems one step at a time.
The easiest way to start this off is to replace existing poor-quality foods with lower-carb, higher-fat alternatives and make daily lifestyle change. If you can reduce the behavioral challenges to a diet during this adaptation period, you’ll make your keto diet more sustainable (the key to effective dieting), as well as more effective and safer.
Avoiding Keto Flu (Step Two): Find Replacement Foods
The majority of the problems that you run into during the keto flu phase is the result of cutting out key carbohydrate sources that double as mineral sources. These foods are crucial for well-being, so when you go full-keto straight away, you’ll suddenly be deficient in key nutrients.
The best example of this is the change from a normal diet to a keto diet, cutting out pulses and whole grains. These key foods contain electrolytes such as potassium, calcium, and sodium, as well as key vitamins and minerals like magnesium and zinc. We tend to be deficient in these often, so making dietary changes can be a huge burden on top of the already-risky dietary intake.
Avoiding keto flu here is actually relatively easy: replace these essential nutrients by including specific foods and supplements to balance out your diet. This probably means relying on nuts and seeds to aid your dietary intake – existing sources of omega-3 fats, zinc, magnesium, and fiber.
By making these changes during the adaptation period, you’ll run into far fewer problems and reduce your risk of suffering from common problems like headaches, weakness, and general fatigue. These vitamins and minerals are key to energy transfer within your body, so it’s no surprise that a deficiency will make you feel awful!
Avoiding Keto Flu (Step Three): Manage Digestion
This is one of the less-discussed aspects of managing keto flu, but it’s also one of the most important for your long-term health.
When you transition to a ketogenic diet, you’ll have to pay more attention to what you eat and how it might affect your digestion. This is the case because ketogenic diets present two problems for digestion.
First, a lack of fiber combined with too much saturated fat can cause constipation and a severely uncomfortable time going to the bathroom. This is something that we all want to avoid. On the other hand, too much unsaturated fat (usually from oils) can bring the exact opposite problem with “loose movements” and an equally-unpleasant time going to the bathroom.
The meals in a ketogenic diet need to be balanced. This means that each meal should have a relatively well-balanced intake of different types of fats and always have plenty of fiber. This is one of the best ways to avoid some of the problems associated with keto flu and the nausea, constipation, or diarrhea that can be a challenge during this time.
You should also focus on low-carb, high-quality, cultured dairy during this time. Things like cottage cheese and Greek yogurt provide a fantastic source of fats and proteins. And even more importantly, they’re prebiotic. This means they’ll provide support to the bacteria of the gut – essential if you’re cutting out sugars and experiencing the effects of this dietary change.
If you’re Already Suffering with Keto Flu: Fixes and Treatments
If you’re struggling through keto flu and you found this article in an attempt to remedy the situation, you’re in luck. The exact changes that caused your keto flu provide a fantastic guide to balancing out your internal problems and getting back to full health.
This starts with addressing the problems we mentioned above:
Hydration is simple. You just need to get more electrolytes into your body and make sure you drink plenty of water. This is as simple as eating plenty of nuts and seeds, using sea salt on your food, and maybe taking an electrolyte supplement to keep yourself in peak condition.
Supplementation is a great way to take care of your body in general and can be a great way to soften the effects of the early days of the ketogenic diet. Some supplements, like ZMA, provide essential vitamins and minerals bundled together – taking all the effort out of a potentially complicated supplement routine.
There are a few key nutrients that you should either be getting from dietary sources or supplementing to make sure you’re getting everything your body needs:
- Vitamin D
These are all essential in your diet already, but they’re a great way to combat the causes of keto flu and protect yourself from any future problems while also shaping up your diet. They’re all pretty cheap, too. So you shouldn’t run into too many problems with such a supplement routine.
Veggie Variety is essential. When you’re on keto, it might be attractive to keep eating that salmon and spinach dish you love, but it’s not the best way to live. You need a wide variety of fruits and vegetables – having staple foods can be a great way to stick with your diet, but too narrow of a focus can mean missing out on key nutrients and making your keto flu worse.
Effervescents are awesome. These are dissolvable tablets that you drop into water, providing a strong multivitamin with electrolytes – and they work pretty well because they’re in water. This can help solve the mineral deficiency and the hydration problem at the same time.
Non-Diet Changes to Help Keto Flu
Not everything about keto flu is solved with diet. While you can cut it off at the cause by adjusting your diet, we’ve already pointed out that this is an adaptive process, so you might have to handle these symptoms in the short term.
Fortunately, there are a few things that you can change about your training and lifestyle to reduce the burden. If you’re dealing with keto flu, these are necessary, but if you’re trying to prevent keto flu in the first place, then they are a great way to help keep yourself healthy and reduce risk. During the adaptation period of the first week, we recommend these changes to everyone!
Reduce Training Volume
This is simple: do less to strain your body while you’re making dietary changes. Too much stress from multiple directions can be a bad thing.
This is a time of serious shock to your system, and you don’t want to make it any harder than it already is. Serious changes or stresses compound, making it very likely that you’ll get ill if you’re laying training stress on top of lifestyle stress and then make huge changes to your diet. If you’re getting stress from all three angles, it’s no surprise you’re feeling bad.
This starts with reducing your overall training volume – whether that means reducing your total reps at the gym or your mileage on the track/road/whatever. Backing off for a week or two while you adapt to keto will be essential to staying healthy. Nothing sets you back quite as badly as injury and illness!
You can keep intensity high but drop the overall volume to ensure that your physiological and psychological stress are nice and low. These things all affect your health, so don’t try to be a hero about it. Take your time, and do it right. You’ll thank yourself in the end.
Reduce Overall Stress
This isn’t the same as point 1 – it’s about combatting lifestyle stress with remedial measures. While you can turn down your training volume, you don’t have as much control over how stressful your life is as a whole. This means you can try to buffer it with proper techniques.
Yoga is a cliche example of relaxing behavior… but it’s also one of the best examples out there. More important is the idea that you’re relaxing and taking time to wind-down, rather than hyping up for exercise or work. This allows you to recover more effectively and reduces the total stress on your body – reducing the overall risk of keto flu catching up to you.
Examples of this type of behavior abound: yoga, a nice walk, a hot bath, stretching, a green tea with friends. Whatever your personal way of switching off and winding down is, find it and practice it during this first week of keto (at the very least) to make sure you’re feeling balanced and allow your body to focus more on relaxation and growth.
In other words: chill out.
If you’re sleeping poorly, your risk of all kinds of injury and illness goes up. Managing this type of recovery variable can make the difference between fending off illness or not.
Sleeping less than 8 hours a night is a surefire way to increase your risk of illness and general unwellness – especially when dealing with stress. Getting enough sleep is one of the most effective ways to handle your health and performance, and is key during this time of transition.
Sleep allows your body to re-balance hormones and improve the overall environment inside your body. It’s the time that you dedicate to improving your recovery processes and balancing out anything that has gone wrong during the day. Damaging this process with late nights and lots of screens near bedtime will only increase your risk of keto flu.
Make sure to get 8-10 hours of sleep in a cool, dark room if you can. We understand that life can get in the way of this, but you have to prioritize sleep. One of the best ways to do this is to ask yourself if that thing you’re staying up late for could be done in the morning instead. Often, the answer is yes, and you’ll feel far more energized to do it then, anyway.
Putting your sleep and recovery first means a better experience, better results, and a much greater chance of staying healthy during that adaptation process. Especially because this is a great habit to get into for your long-term progress!
Set your Expectations
We’re firm believers that your own expectations are some of the most problematic things in the world. If sadness comes from a mismatch between expectations and reality, the keto flu is one of the most obvious examples in health and fitness.
During this period of enormous change, on a strict new diet with restrictive calorie-intake and carb intake, it’s very little surprise that you feel sub-optimal. Sadly, this is an inevitability – whether it’s from keto flu or simply a sense of feeling a little drained.
The reality is that this change is a long-term investment that comes with some mild short-term sacrifices to your lifestyle and exercise performance. The difference is that it also brings the possibility of much better long-term performance and physical change.
These are your goals, and this short period of discomfort is simply a way of achieving them. We know that keto’s first few days can be rough, but they may well give way to a lifestyle that suits you, your needs, and your goals far better than what you were doing before. Put these things in perspective and keep them there.
The keto diet is a great change you can make if you’re feeling like the carb-centered focus of normal diets aren’t helping you. However, it’s not a small change, and the way that it can affect your body may come with some negative side effects.
As discussed above, the keto flu is a collection of symptoms that you may experience in response to these changes. However, many of the more severe effects can easily be avoided by adjusting your diet and lifestyle, while others simply come from taking a more patient tact and addressing the long-term benefits of the keto diet instead of rushing into it just because you’re excited.
Patience, planning, and developing better day-to-day behaviors is the key to success on the keto diet. These may help you avoid the keto flu in the short-term, but in the long-term, they teach you essential lessons about how best to diet, how to handle important changes to your life, and how changing your non-dietary factors can have profound, far-reaching benefits!