How do you know if you’re in ketosis?

How do you know if you're in ketosis

How do you know if you’re in ketosis? What are the signs your body is in ketosis and that you’re doing the keto diet well?

There are several signs your body is in ketosis, and as you adapt to the keto diet you’ll get more tuned into how ketosis feels for you.

This is important because if you’ve just started the keto diet you’ll want to be sure that you’re doing everything correctly.

You’ll want to be assured that you’re on the right path.

Each person will respond differently.

However, there are some signs that your body is in ketosis which are experienced by most people.

By listening to your body you can very often get a good idea if you’re in the desired state or not.

This is something that becomes easier the more times you enter ketosis.

You will come to recognize and enjoy the feeling that ketosis will bring you.

What is ketosis?

How do you know if you're in ketosis

The keto diet is a low carb, medium protein and high fat diet. Carbs are kept to below 20g net per day.

This is a lot lower than you would normally eat on a standard western diet.

Your body will always choose to metabolize carbs first. This is the easiest way it will metabolise the food you eat into the energy you need.

With the keto diet you’ll haveinsufficient carbs for your immediate energy needs.

So your body will switch to its second metabolic pathway. It will begin to burn fat for fuel.

This means you’ll be using  your fat stores for energy.

While doing this your body will produce ketones, which gives the keto diet its name.

It is the aim of all keto dieters to reach ketosis.

In this state you’ll be able to access all the amazing weight loss and health benefits of the keto diet.

How long does it take to get into ketosis?

How do you know if you're in ketosis

Each person is different, and some will be able to reach ketosis more quickly than others.

Anywhere from about 3-4 days to more than a week would be possible.

However, you’ll need to be sure that carbs are limited to under 20g each day.

If you have been on a keto diet before, you will be more fat adapted than someone trying the diet for the first time.

When you are fat adapted your body is able to burn fat quite quickly once your glucose stores have been depleted.

For a first time keto dieter, any time up to a week would be more usual.

Read How long does it take to go into ketosis for a more in depth look at the time needed for ketosis.

How do  you know if you’re in ketosis? Signs and symptoms of ketosis.

How do you know if you're in ketosis

There are many signs and symptoms of ketosis. As you become more familiar with the keto diet, you will recognize these in your own body.

While most are beneficial, there are a few that are negative.

However, none are detrimental to your health.

Not everyone will experience them all, and for that reason only the most common ones are discussed here.

Bad Breath

common signs you're in ketosis

When most people think about the keto diet, the words “Bad Breath” are usually not too far away and with good reason.

Almost every one who is starting the diet will experience this sign. This can be a big problem for many keto dieters, especially in the first few days.

Very often this is an issue that becomes less obvious after you have been on the keto diet for a while.

Thankfully, there are a few  effective things that you can do.

Keto bad breath is different from regular bad breath.

With the regular BB the culprit or culprits are normally poor dental hygiene and gut problems. Some medications, dry mouth or an infection can also cause issues.

Keto bad breath is characterized by a fruity smell or a smell close to nail varnish remover.

Initially bad breath can also be caused by dehydration. This can be a problem during the first few days on the keto diet.

Dehydration can be caused due to the fact that the fat cells contain a lot of water.

When they are used for fuel, the water they contain is released.

This  is the water loss that will cause you to visit the bathroom more often.

If you don’t make sure you’re drinking more than usual you may find you become dehydrated.

Aim for a few more glasses of water than you would normally drink.

The other two reasons are both to do with being in ketosis, which is a good thing – although the outcome is not so great!

As the extra ketones are removed from your body they will produce acetone, which gives your breath its distinctive smell.

To a lesser extent, ammonia is also a culprit. This is produced as your body digests proteins.

Make sure you are eating the recommended amount of protein only.  There is no need to eat more protein than you need.

This is about 56g per day for men and 46g per day for women.

Increase the amount of time you spend cleaning your teeth, and consider using a tongue scraper. The tongue is a major source of bacteria in the mouth.

So by taking care of these things, you should be able to deal with bad breath:

  • Make sure you are drinking enough
  • Don’t go over the recommended amount of protein – check your macros with this calculator
  • Increase the amount of time you spend cleaning your teeth

Appetite suppression

How do you know if you're in ketosis

This is a surefire way to know that you’re in ketosis. It’s also one of the positive effects of the keto diet.

The keto diet recommends that you get about 75% of your daily allowance from healthy fats.

Fats are very satiating, and will cause you to feel full for longer.

The diet will also stabilize your blood/insulin levels, and this will  reduce the amount of times that you feel hungry.

Chronically raised insulin levels can cause leptin resistance. Leptin is a hormone that reduces your appetite.

It is completely normal to notice a big decrease in your appetite once you’re in ketosis.

Increased focus and feeling of well-being

common signs you're in ketosis

This is a very common feeling when in ketosis.

Indeed, it is a major reason for many people to remain on the keto diet even when they have reached their weight loss goals.

This impact on cognitive function has been well studied. You can read more here and here.

Most people feel very much more alert and with sustained levels of energy throughout the day once they’re in ketosis.

This is not surprising as the keto diet has been found beneficial for many neurodegenerative diseases.

Some people have also noticed a decrease in their anxiety and level of depression.

Weight loss

common signs you're in ketosis

This may seem obvious, but weight loss follows a pattern with the keto diet.

A lot of weight is lost during the first few days, but this is mainly water which is released from the fat cells.

Once the first few days have passed, weight loss should steady but still be significant . This will remain even if you’re eating much more fat than normal.

It is when you notice this slowing down of weight loss, but still losing weight, that you will most probably be in ketosis.

This is normal, and you should not aim to lose weight too fast.

If this is happening to you then you need to increase the amount of fat you’re eating until weight loss slows.

High ketone levels

Common signs you're in ketosis

This is what you are aiming for and  you should be strict about keeping within your carb macros and never eating more than 20g net carbs each day.

At this level just about everyone will reach ketosis.

It’s worth mentioning that some people can increase this significantly.

But  you would need to be testing your ketone levels while you tried to work out your own personal carb limit.

The only way to accurately know if you are in ketosis is to use a meter and test your blood.

Read here for more information about the keto mojo meter which is one of the most popular meters on the market.

Other ways of testing your ketone levels are with urine strips or with a breath meter. The breath meter works by measuring the levels of acetone in your breath.

Both of these methods tend to be cheaper than blood tests, but are less reliable.

How do you know if you're in ketosis


The early days on the keto diet can make you feel tired and lethargic as your body adjusts to using fat for fuel.

It is at this stage that you can feel some negative effects of the keto flu.

This stage does not normally last past the first week, and you should start to experience some effects of being in ketosis.

If you are keeping to under 20g of carbs and are feeling relaxed, focused and energetic, it is almost guaranteed that you have reached ketosis.

As you become more used to the diet, you will reach this stage sooner.

The only way to tell for sure is by using one of the meters available and to test your blood. This will also tell you just how far into ketosis you are.

A meter is not essential if you are following the diet correctly.

However, if you want to find out what your personal carb limit is you will have to test regularly.

This way you’ll be able to see the effects of any increase in your carb allowance, and adjust until you reach your own best level.

This can be very useful if you want to be in ketosis, but want to be able to eat the maximum amount of carbs.

Once you’re in ketosis you will know that you’re doing the diet well.

Further, you’ll be able to look forward to reaching your weight loss and health goals in the quickest possible time.

These articles may also interest you:

How long does it take to go into ketosis

keto mojo meter best keto blood meter

exogenous ketones

How many carbs can you have on a keto diet, making sure you’re eating the right ones



  1. Dear Judy

    This was indeed a very interesting read. I would like to try the Keto diet. Do you have any Keto diet recipes? This will give me a better idea of what a typical plate of food in the Keto diet would look like. Many thanks!

  2. Great article! I learned so much about Keto. However I do not have much time to prepare meals. Could you do an article about easy Keto meals or Keto meals I could get from fast food resturants?

  3. Thank you for this informative article. I think it is important to be in tune with your body. Knowing what happens when your body goes into ketosis will better prepare you for the this process.

    1. Hi Rebecca,

      Thanks for you comment.

      You are completely right – preparation and knowledge is everything when it comes to the keto diet. It really can make all the difference between success or failure when it comes to your goals.

      Many thanks for your kind words about the article

      Best wishes,


  4. Great information as normal.

    I had been considering joining a keto diet but this post is making me think twice as I do not want to have bad breathe.
    Ha ha..I also would not survive since I love eating so the suppression of appetite would kill me

    Does this happen to keto diet people who are vegans?

    1. Hi Thabo,

      Thanks for your comments – thankfully keto breath can be dealt with as the post says!

      The suppression of appetite is great, but not so great that you’ll never want to eat again – I’m confident that you are still going to enjoy your meals.

      Vegans have exactly the same response to the keto diet as anyone else. They just have to take more care to make sure they’re reaching all their nutritional needs.

      Best wishes,


  5. I’ve done ketosis diets several times in the past. For me, the sure way to tell I’ve reached ketosis is the acetone smell in breath and urine as well as the improvement in well being. I’ve always had a rough transition to ketosis with the “keto flu” sluggishness so I know when it stops and I haven’t had any carbs that I’m working on ketone bodies!

    1. Hi Jukka,
      Thanks for your comment.

      You’re a great example of a seasoned keto dieter – you recognise the signs of ketosis in your own body and know you’re on the right path.

      I also love the feeling of well being that ketosis brings.

      Best wishes,


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