How Long Does it Take to Get into Ketosis?


The Keto diet is one of the most popular prevailing diets, which people worldwide are quickly catching onto. 

Although the basics of the diet are straightforward, with low carbohydrate intake and an increase in healthy fats in your diet, there are still a lot of questions surrounding ketosis, such as how does it work?

What can you eat on a keto diet?

And how long does it take to get into ketosis? 

If you’ve been on the keto diet for some time now but aren’t yet seeing the results you were hoping for, this guide will clear up any questions about why you might not yet be where you want to be. 

So how long does it take to get into ketosis, and is there anything you can do to get there quicker?

Here is an in-depth look at how long it takes the body to reach ketosis. How it can vary from person to person, and what you can do to get your goals quicker but safely.

How Long Does it Take to Get into Ketosis – The Facts


As with any medically proven diet, reaching a point of ketosis takes time.

Ketosis describes a metabolic state during which the body breaks down fat stores for energy instead of carbohydrates. 

The fastest and most effective way to do this is by lowering the carbs you consume daily and upping the fat intake with beneficial fats from foods such as fish, nuts, and healthy oils like olive oil. 

The time it takes to reach ketosis varies significantly from person to person. 

The quickest way to get into ketosis, for the average healthy adult, is to reduce carb intake to between 20-50g per day. Of course, this will depend on your fitness level, age, and current weight. Use a tool like the keto calculator to figure this out.

Speaking to a personal trainer, dietician, or physician can give you a more accurate idea of how many carbs you should eat daily for your circumstances. 

As a general rule of thumb, tests have shown that reducing carb intake to between 20 and 50 grams should see the body getting into ketosis after three or four days, but for some, it could take more than a week. 

A few things can speed up the time it takes to get into ketosis. These include:

Applying one or more of the above can result in a significant variance regarding how fast your body gets into ketosis. However, doing this safely and not everything simultaneously is essential to avoid impairing your health. 

Keto supplements should also be used with care, ideally with the advice of a medical professional or dietician. Find out more about keto supplements here to better understand safe and proper use. 

Knowing When You’re in Ketosis

People struggle with knowing precisely when they’ve reached ketosis, especially when new to the keto diet. 

Some people indicate that they’ve gotten into ketosis by the symptoms that can develop. These are likened to flu-like complaints, such as fever, thirst, and fatigue. However, these aren’t the most accurate way to indicate you’re in ketosis. 

So, how do you know when you’re into ketosis? Read our article on the symptoms of ketosis without testing.

Measure Your Ketone Levels

The most accurate way to determine whether you’re in ketosis is by measuring your ketone levels.

Ketones are measured in three ways, either using breath, urine, and blood samples. 

The cheapest and most accessible test method is usually done with a urine sample. However, this isn’t the most accurate way of deciphering whether or not you’re in ketosis. 

The breath is used to measure the acetone levels. This can be done using a ketone breath meter which studies have proven to be one of the most effective ways of determining when you’re in ketosis. 

The third way to measure your ketone levels, and establish whether or not you’re in ketosis, is with a blood test. These can be purchased as home kits and involve a simple finger prick test. 

Studies state that between 1.5 and 3.0 millimolar per liter indicates being in a ketogenic state. 

So, besides physical testing, are there different ways to know whether you’re in ketosis?

Signs and Symptoms of Being in Ketosis

Purchasing keto testing kits can be costly; some may argue they’re too intrusive. In these cases, there are other ways to indicate you’re in ketosis.

While these might not be as accurate as the blood tests, urine strips, and ketone breath meters, all of the below are still good indicators that your body has reached ketosis. 

Flu-Like Symptoms

As we briefly touched up earlier. A sign that you’re in ketosis might show by portraying cold and flu symptoms such as feeling drained, nausea and vomiting, weakness, and fever. 

These symptoms are often short-term but should be monitored and discussed with your physician if it’s persistent or causes you any concern. 


Another indication that your body has gone into ketosis is an increased feeling of fatigue. You might feel more exhausted than usual throughout the day. This fatigue usually happens in the early stages of ketosis due to the lack of electrolytes. 

Supplements such as these electrolyte drinks can help with these feelings while your body adjusts to the keto lifestyle. 

Constipation or Diarrhea

You might notice a change in stool appearance and bowel movement regarding regularity or change in texture. This is normal and is what is referred to as keto poop. This is not usually a cause for concern and will settle in time. 

Decreased Appetite

It’s still unclear why some people have a noticeably suppressed appetite after getting into ketosis. However, some experts state that it’s due to increased protein intake. 

There is also evidence that ketones can influence the brain to minimize appetite. 

Bad Breath

A more unpleasant side effect and sign that you’re in ketosis is what’s known as ketone breath. In other words, bad breath. 

Bad breath is one of the most common signs of ketosis and is thought to be associated with increased protein intake and the ketone acetone, which exits the body via your urine or breath. 

Not great for your romantic life, but indeed a sign that you’re in ketosis. Keep some sugar-free gum handy to reduce this unfortunate ketone indicator. 

Weight Loss

The goal for many people starting a ketone diet, aside from improved health, is weight loss. Weight loss within the first few weeks indicates that you’re doing it right and your body has gotten into ketosis successfully.


Some people might experience sleep disorders such as insomnia when adapting to a keto diet. This is usually due to the extreme change in your carbohydrate intake and is only a short-term problem that should level out after the first week or two. 

Final Output

The primary fact to take away from all this is how long it takes to get into ketosis, depending on your carb intake, general health, and fitness levels. 

Some people might get into ketosis within 2-4 days, while others may take more than a week. 

Suppose you want to get into ketosis faster; there are a few things you can do to speed the process up safely. These include:

  • Reducing your carb intake further
  • Partaking in exercise 3-4 times per week. 
  • Increasing your consumption of healthy fats. (Found in foods such as mackerel, salmon, nuts, and healthy oils). 

If you don’t think you’re seeing the results you should be after changing to a keto diet, check out this beginner guide to keto to find more details about what to eat and how to monitor your carbohydrate intake correctly. 

There are many ways to check whether or not you are in a ketosis state, such as physical symptoms like changes in stools, flu symptoms, weight loss, and bad breath. 

However, the most accurate way to ascertain whether or not you’re actually in ketosis is by testing with urine strips, ketone breath meters, or finger prick blood tests. 

Overall, a good indication that you’re in ketosis is that after a week or two, you will see changes in your physical health, such as weight, skin condition, and energy levels. So if you’re noticing a positive difference with all of the above, try not to overthink it too much. Chances are, you’re in ketosis.

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