Does the keto diet make you cold?

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When starting a new diet, especially one as life-changing as keto, there are many questions about the expected side effects, and one of those questions asked by many is, does keto make you cold? 

So, is being cold a sign that you’re in ketosis? Let’s find out. 

Throughout this guide, we will cover some of the reasons why you might feel the cold more than usual when starting a keto diet. We will also look at how long you can expect these symptoms to last and ways that you can reduce the chill. 

One of the most common side effects of ketosis is the keto flu, which is one thing that can be linked to feeling cold, so before anything else, we’ll look into that in more depth. 

What is the Keto Flu?

keto flu

Despite ketosis being thought to improve your general health and well-being in many ways, a couple of unpleasant side effects go hand-in-hand with the diet during the early days. One of these is the common keto flu. 

But what is it? And why does it occur?

The keto flu is exactly what it’s named after. The flu. Or at least symptoms that replicate it. 

The reason people following the keto flu may experience these unpleasant symptoms is because of the lack of carbs being taken in. Lowering your carb intake means that your body starts using fat and ketones for energy instead of the sugar from carbohydrates. 

This drastic change in energy use will be a shock to your body. You might go into a state of surprise, which, while sounding drastic, means that your body might start to experience withdrawal symptoms from the lack of carbs. 

This is the same outcome for someone who drastically reduces their caffeine intake or suddenly stops taking an addictive substance. It’s the body’s way of crying out for something. 

Of course, what’s the number one symptom of the flu? Fever and chills. 

So, this would be the common denominator for why you may feel cold on keto. 

However, you’ll be glad to hear that these ketosis symptoms are only short-term and nothing to be concerned about. 

If you are at all apprehensive about the uncomfortable side effects you’re experiencing, speak with a doctor to rule out any underlying health conditions and put your mind at ease. 

Other symptoms to look out for that might indicate your experience with the keto flu are the following:

  • Headache
  • Drowsiness
  • Insomnia
  • Stomach cramps
  • Dizziness
  • Fatigue
  • Muscle ache
  • Weakness
  • Constipation
  • Diarrhea
  • Nausea/vomiting 
  • Mood swings

Why Does Keto Make You Cold – Causes and Reasons

does keto make you cold

As we’ve already covered, the general cause for feeling cold on keto is because of what’s known as the keto flu. 

But are there other reasons why you might be feeling the chill?

The answer is yes, and here’s why.


Some people find it works best when combined with intermittent fasting when practicing a keto diet. This can bring on side effects of its own, including feeling cold. This is because when the body’s blood sugar levels decrease, a hormone called orexin is repressed. This hormone both regulates and increases the body’s temperature.


If you’re experiencing nausea or vomiting when entering ketosis, try not to worry. This is a common side effect and usually nothing to be worried about. As with anything, though, if this is excessive or causing you any concern, do speak with your doctor or personal dietitian, who can provide you with an additional examination to ensure everything is as it should be. 

One side effect of nausea is feeling cold. This is because the body goes into fight-or-flight mode when experiencing changes such as those that occur at the beginning of ketosis. 

Reduced Thyroid Levels

T3 or Triiodothyronine is an active thyroid hormone connected with your metabolism. Because this is linked to your calorie and carb intake, it can mean that when entering ketosis, something called “diet-induced hyperthyroidism” occurs. This can lead to a drop in body temperature. 

There are some supplements you can take while in ketosis that can help you regulate the thyroid. In this guide, you can read more about the best vitamins to take on a keto diet. Remember, it’s vital to seek advice from a doctor before taking any supplements, especially if you have any health concerns or allergies or are taking any form of medication. 

Fat Loss

For a lot of people on a keto diet, the main goal is weight loss, and this is because keto is proven to be one of the most effective ways to burn fat quickly and safely. 

If you think of fat like your loft insulation, it does the same job. So having excess fat is going to keep you warmer. When you start to lose this fat, you’ll notice you begin to feel the cold a little more than you did before. If this is the case, well done; your keto diet is working as you intended. 


One part of the keto flu you might experience is cold sweats. 

When your body has reached a state of ketosis, it may begin to sweat excessively. This is your body releasing heat and recognizing that it needs to start burning fat instead of carbs for energy. Good news!

This also explains why many people say they feel more thirsty on a keto diet. 

Although you might think excessive sweating sounds gross, don’t worry. This is a good sign. It may also go hand-in-hand with other not-so-delightful symptoms, such as bad breath and potent urine. But once again, don’t panic; these unpleasant symptoms are short-term and a positive sign that you’re doing something right. 

Low Blood Sugar

A drop in blood sugar levels can happen during a state of ketosis. 

Hypoglycemia is the term used for what happens when your body experiences a lack of blood sugar, which is what happens during ketosis. This will only be a cause for concern if you have diabetes. In this case, you should seek medical advice immediately. 

Although it can be safe to go on a keto diet when you have diabetes, it should be discussed with a professional who can better advise you based on your personal medical record. 

How Long Will You Feel Cold on Ketosis?

The good news is that all the symptoms I’ve described will be short-term. It’s just that your body adjusts to the state of ketosis. 

How long you feel cold in ketosis depends on your circumstances. If you’ve dropped the pounds significantly, you might notice you’re more susceptible to the cold than before in the long term. However, you’ll soon adapt to this, and your new healthy lifestyle and better mental well-being will make it all worth it. 

You never know; you might not even experience any symptoms whatsoever, and some don’t. 

The important thing is to persevere. Don’t let these minimal side effects come between you and your end goal. We promise they won’t last long, and the result outweighs the few days of discomfort tenfold. 

How To Prevent Keto Flu and Feeling Cold in Ketosis

Although some of these symptoms might be unavoidable, there are some things you can do to reduce them slightly, such as the following:

  • Stay Hydrated – Drinking plenty of fluids can help to rehydrate your body, especially during periods of excessive sweating, which is vital. You might find that you need to drink more than the recommended daily allowance to keep up with your thirst levels. There are also some great electrolyte supplement drinks that will help you replace vitamins and minerals lost through dehydration. 
  • Don’t Cut Out Carbs Altogether – Some people get confused when they hear the words keto and presume it means a ban on carbs entirely. This is false. A small number of carbs are perfectly fine on keto, and cutting them all together can put you in a state of starvation. Keep consuming a healthy amount of carbohydrates from foods such as leafy greens, fruit, nuts, and seeds. 
  • Take it Slow – The key to any diet is not to rush. Although you might want to get into ketosis fast, any drastic, sudden change in your diet can do more damage than good. Start by reducing your carb intake slowly, and over the following weeks, you can reduce it further. This way, your body won’t go into a significant amount of shock, which causes flu-like symptoms and chills. 
  • Create a Meal Plan – When starting a keto diet, some people might be put off or concerned about eating the correct amount of carbs, which can lead to eating the wrong kind of food. Set yourself a meal plan, count your macros daily, and keep your diet varied. You can find a great selection of keto foods here

A Final Breakdown

It’s clear that ketosis comes with its challenges; however, the good news is that these only last for a while, at least not in most cases. 

Side effects such as the keto flu and feeling cold or nauseous should clear up within a few days once your body has adapted to its new diet and adjusted to burning fat for fuel. 

In the meantime, consider looking at various supplements that make the transition into ketosis a little less uncomfortable. Make sure you stay hydrated and use your carb allowance to its full potential. 

Although there are things you can do to try and keep warm during this stage of your new diet, unfortunately, the best thing you can do is be patient, and trust us when we say this won’t last long. 

Perseverance is a virtue in any diet you want to see results from—especially keto.

The Author

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John has been learning about and experimenting with low carbohydrate diets since the around 2006. He has successfully used the keto diet to lose over significant amounts of weight in the past and currently follows a low carb diet for a variety of reasons including general health, weight management, and managing mood levels.

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