12 Side Effects Of Keto Diets

Ketogenic diets are popular thanks to their ability to help dieters lose weight quickly. While more and more doctors are coming on board announcing the diet is safe, and some even recommend it to their obese patients, it is essential to know about the side effects that some people experience.

What are the worst keto side effects? Some common short term keto side effects include keto flu, headaches, tiredness, and nausea.

There are a number of different side effects when it comes to eating a ketogenic diet. Some are great, and others are not so good. Keep reading to examine what some of these side effects entail.

1. Keto Flu

The Keto Flue is by far the most common side effect that you may experience when starting a ketogenic diet, so I’m going to be focusing a good portion of this article talking about it.

So you’ve researched keto, and you’ve been blown away by all the benefits it provides. The first day or two are just like any other diet. You’re probably a little hungry and maybe even a little cranky, but you’re pushing along because you know that once you enter ketosis, the whole game changes. All of a sudden, you hit what feels like a brick wall.

From out of nowhere, you’re not feeling good at all. You’re also exhausted, are easily agitated, have a pounding headache, and can’t concentrate on anything to save your life.

Welcome to the keto flu! Many of us get this in the beginning. If you’re one of the lucky ones who don’t, congratulations. For the rest of you, wear it like a badge of honor. Just realize that keto flu is not an actual flu. Although it isn’t any fun, it can’t be passed onto other people.

The unfortunate truth is that most of us are going to feel at least one of these symptoms during the first couple of weeks on keto, with the worst happening 3-7 days into your new lifestyle. This is when your body makes the change to ketosis, and your body isn’t happy that you’ve taken its carb supply away.

When you think about it, keto flu can serve as validation that you’re on the right track because if you’re not going into ketosis, you’re not going to experience it. Also, keto flu doesn’t last long, and before you know it, you’ll be feeling even better than you did before.

Let’s take a look at some of the most common symptoms of keto flu:

So, the next question I usually get asked when talking about keto flu is why we get it in the first place. I usually start by telling them that it’s because their body hates them and watch the confusion on their face before giving them the actual answer.

When you go from eating a carbohydrate-heavy diet to hardly eating any at all, the insulin levels in your body plummet quickly. When this happens, your liver starts taking any fat it can find and turning it into ketones since there isn’t any sugar glucose to be found. Those ketones then cause your body to start burning fat for energy. You are now in ketosis, which is your goal on a ketogenic diet.

Although you’ve accomplished your initial keto goal, all the organs in your body, along with your brain, are trying to figure out what is happening. They are so used to using carbs for fuel that they need to learn how to adapt to this new energy source.

Once your insulin levels become lower than usual, your body starts releasing more water and sodium in urine waste, which is why you may find yourself having to use the bathroom more often in the first couple weeks of the new diet.

These changes usher in the rapid weight-loss period, but the loss of sodium and water is what leads to keto flu symptoms. It’s important to note that not everyone experiences keto flu in the same way. Some people may feel agitated and tired, while others will experience the entire spectrum of possibilities.

Is There A Cure For Keto Flu?

For most people, keto flu symptoms will go away on their own. Although there is no exact time frame, this could be anywhere between two days and two weeks into a ketogenic diet. That doesn’t mean you have to suffer because there are actually some things you can do to start feeling better right away.

  1. Drink more water and consume more salt – For the majority of people who suffer from keto flu, this is often all you need to feel better. Salt and water loss is the most common cause, so increasing both can knock out your symptoms. Whenever you feel any of the symptoms above coming on, have a glass of water with half a teaspoon of pink Himalayan salt mixed in. If you can’t stomach the taste, add some flavor drops to mask the salt.
  2. Eat more food – If you find that you aren’t feeling hungry because you’re experiencing symptoms of keto flu, fight through it, and eat anyway. Not eating may actually make your symptoms worse.
  3. Eat more fat – If you’re still not feeling well, try adding additional fat into your diet. Your body may be trying to go into starvation mode, and eating more fat may prevent that. This step can be as simple as adding some butter to the foods you’re eating.
  4. Slow down on exercise – If you’re experiencing keto flu symptoms, slow your physical activity down a bit to see if it improves. If it does, take it easy for at least a month before increasing what you’re doing. If you feel like you need to get moving, take a leisurely walk and get a good stretch in, but nothing more than that.

2. Diarrhea

While diarrhea doesn’t happen nearly as frequently as keto flu, it happens enough for me to put it at number two, no pun intended.

One possible reason for this side effect is the overwhelming of the gallbladder. You’re eating a lot more fat, and your gallbladder may be having trouble making enough bile to break it down.

A general lack of fiber could be another reason. A lot of people eliminate whole grains from their diet and don’t replace it with fiber-rich fruits, vegetables, or nuts. If this is your problem, consider adding some of these to your diet:

Keto-Friendly Fiber-Rich Vegetables

  • Artichokes
  • Leafy greens
  • Bok choy
  • Lettuce
  • Cucumber
  • Broccoli
  • Zucchini
  • Cauliflower
  • Celery
  • Brussels sprouts
  • Kale
  • Cabbage

Keto-Friendly Fiber-Rich Fruits

  • Blueberries
  • Avocado
  • Tomato

Keto-Friendly Fiber-Rich Nuts and Seeds

  • Walnuts
  • Chia seeds
  • Almonds
  • Hemp seeds
  • Flax seeds

The third possible cause of diarrhea on a ketogenic diet is that your body may be rebelling against artificial sweeteners or the fact that you’re having more dairy. Try cutting back on these and see if it helps.

3. Leg Cramps

Leg cramps are the bane of my existence when it comes to keto. Speaking from experience, they don’t happen all the time, but when they do, they are not pleasant.

These cramps most commonly occur when you’re asleep. If you’ve ever experienced a Charley horse, then you already know what I’m talking about. I’ve found that my leg cramps occur most frequently when I stretch my legs in bed. The muscles in my calf tighten up, and some choice language typically flows from my lips.

Leg cramps are the result of not having enough sodium in your bloodstream. You will do yourself a huge favor by making sure you stay hydrated and get plenty of salt in your diet. Pink Himalayan salt works best.

If my leg cramps get too bad or happen too frequently, I have a keto electrolyte supplement that does wonders.

4. Keto Breath

When you are moving into the fat-burning parts of a ketogenic diet, you may experience temporary bad breath, commonly known as keto breath.

The ketones you’re burning aren’t just excreted in your sweat and urine. They also are released in your breath. The ketone released in the breath is known as acetone. It tastes a little metallic and can lead to breath that doesn’t smell very good.

Keto breath doesn’t last the entire time you’re following a ketogenic diet. Most people will find it goes away after a couple of weeks, but that doesn’t help you when you’re going through it. Sugar-free mint gum or a breath freshener works to mask it temporarily.

You already know that you’re supposed to brush your teeth twice a day, but you might want to increase this when you have keto breath. After brushing, use mouth wash several times a day to counteract the ketones.

5. Heart Palpitations

You might be surprised to learn that heart palpitations are extremely common, but you don’t even know you’re having them. They don’t begin to worry you until you can actually feel one happening.

When you have a palpitation, you get the feeling that your heart is going to beat out of your chest. You may also feel a slight flutter or feel like it skips a beat entirely. For the most part, heat palpitations are nothing to worry about, but if you find they’re happening regularly, you may want to consider getting it checked out.

If you are on keto and start to feel palpitations, it may be because you need some potassium. Potassium is one of the most vital electrolytes used by your body.

The fix for this one is simple. Increase your levels by eating keto-friendly foods that are rich in potassium. Some of the best sources include:

  • Avocado
  • Plain coconut water
  • Brussels sprouts
  • Pork chops
  • Mushrooms
  • Clams
  • Summer squash
  • Fatty fish like salmon, mackerel, and halibut
  • Spinach and other leafy greens
  • Pumpkin seeds

6. Hypoglycemia

Hypoglycemia is just a scary sounding word for low blood sugar. It may happen after you start a ketogenic diet, but before you are actually in ketosis. You may experience agitation and a general lack of energy, but these symptoms should go away once you’re completely fat adapted.

7. Frequent Urination

There are a couple of reasons that you may be urinating more often on keto. As mentioned earlier, glycogen plays a big part in holding water in your body. With your body using up its glycogen store, you’ll urinate more often.

Urinating frequently may be a little annoying, but it isn’t usually much to worry about. Be sure you keep drinking your water because you don’t want to become too dehydrated.

8. Sugar Cravings

If your favorite snacks were always full of sugar, you’re bound to have sugar cravings when cutting them from your diet. Sugar acts the same way as addictive items such as cigarettes and drugs. When you aren’t getting it, your brain is going to tell you it needs it.

Sugar cravings can make you extraordinarily crabby and make your anxiety levels go through the roof. One of the best things you can do to beat these cravings is to replace them with foods that are full of healthy fats and proteins such as fatty fish, whole effs, seeds, and nuts.

9. Problems Sleeping

For some people, keto can cause sleeping issues. The diet can cause short-term insomnia, and even though it’s only a temporary side effect, not getting enough sleep for even a little bit can have a negative impact on your productivity, focus, and energy.

If you find that you’re having trouble sleeping on keto, here are some things to try:

  • Exercise earlier – Adrenaline is released into your body each time you exercise. If you are working out close to bedtime, your body might have trouble stabilizing the adrenaline, making it nearly impossible to wind down. Working out at least four hours before bed should help.
  • Keep your room cool – If your room is too warm, you might have some trouble falling asleep. If you keep your room around 65 degrees Fahrenheit, you should be able to sleep easier.
  • Stop using electronics before bed – Your brain releases a chemical known as melatonin when it’s time to go to sleep. According to Cleveland Clinic, who has done a lot of research on this topic, the blue light emitted from your electronics makes it harder to fall asleep and makes it nearly impossible to get quality sleep.
  • Eat your last meal earlier – Eating too close to lying down may lead to heartburn and indigestion. Both of these lead to discomfort and makes it nearly impossible to fall asleep. If possible, eat your final meal or snack at least four hours before going to bed.
  • Take melatonin supplements – Taking a melatonin supplement provides the same benefit as your brain releasing it. For most people, 5mg should be plenty. For best results, take it and lie down immediately. A dissolvable tablet such as this one will give you the best results.
  • Try lavender oil – Lavender oil has been found to relax the body when it is smelled. A few drops of lavender oil on your pillow helps turn off your brain, allowing you to fall asleep naturally. I recommend lavender oil by Majestic Pure.

Extremely Uncommon Symptoms

The following symptoms occur far less frequently than the ones above, but I still wanted to talk about them a bit.

10. Vitamin Deficiency

If you aren’t watching your diet and eating plenty of foods that are rich in nutrients, you may experience deficiencies in Vitamins A, B, C, and K.

These vitamins are vital for your everyday health. Various combinations of these vitamins are responsible for providing you with energy, keeping your immune system running smoothly, fixing any problems with your tissue, and forming your red blood cells.

The first thing you should do is ensure you’re eating plenty of nutrient-filled foods such as almonds, walnuts, steak, raspberries, strawberries, salmon, avocado, broccoli, eggs, spinach, and cauliflower. If you still don’t feel like you’re getting enough vitamins, consider taking a supplement.

11. High Cholesterol

You might be surprised that this side effect is listed under the extremely uncommon section since you’re transitioning into a high-fat diet. It makes sense because most people assume that this type of diet will automatically cause heart disease and send your cholesterol through the roof.

The fact of the matter is, keto has been found to lower bad cholesterol in many people, according to a study published by the National Library of Medicine.

If you’re following keto correctly, you should see your good cholesterol, otherwise known as HDL cholesterol, increasing while the bad LDL cholesterol should go down. If you’re eating a clean keto diet and still seeing a spike in your bad cholesterol, you may want to contact your medical care provider to make sure you aren’t having complications.

12. Menstrual Cycle Disruption

Females who drastically cut calories may experience a disruption in their menstrual cycles. Missing periods is a horrible side effect for women because it has a negative impact on your fertility and is also a contributing factor for osteoporosis.

It’s important to know that cutting calories by a large margin is not required to get into ketosis. Yes, keto follows calories in, calories out to a certain extent, but there is much more to it than that. When you are getting plenty of fat and a decent amount of protein, you’ll be satiated naturally and won’t have to overeat.

Another thing to keep in mind is that if you’re missing your menstrual cycle regularly, this could be the sign of a significant health problem. Be sure to contact your physician for an appointment.

Related Questions

Will keto work without exercise? You do not have to work out while on keto to experience the benefits as long as you are sticking to the rules of the diet and eating at a caloric deficit.

Why is a ketogenic diet becoming so popular? The diet promotes stable blood sugar and steady weight loss while being easy to follow and understand.


Derek Masters

Derek Masters is an Amazon best-selling author. After much research, he began keto at 381 pounds in the middle of 2019. Losing 60 pounds and counting, he wants to share what he's learned with others who wish to learn about the ketogenic lifestyle

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