Ketosis Onset: How Long Does It Take to Enter the State of Ketosis?


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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.

Factors Affecting the Time to Enter Ketosis

Every human being is built differently so the ketosis timeline may vary from person to person. The time needed to enter ketosis is influenced by a number of factors; some can be managed, and some need acceptance.

  1. Metabolism

The higher your metabolic rate, the faster you can enter ketosis. People with a low metabolic rate burn fewer calories at rest per unit of time. A few ways to improve your metabolic rate over time include:

  • Remaining active throughout the day
  • High-impact cardio training
  • Building muscle
  • Staying hydrated
  • Managing stress
  • Quit skipping meals (particularly breakfast)
  • Improve sleeping habits/patterns
  1. Carbohydrate Intake

If an average person consumes 2000 calories daily, around 1000-1400 come from carbohydrates; this adds up to about 300 grams of carb intake daily. For the body to enter ketosis, you need to reduce your daily intake below 50 grams.

Your body may enter ketosis faster if you aim for as low as 20 grams of carbs daily. Everything you eat or drink throughout the day must contain no more than 5-10% carbohydrates. 

  1. Fat Consumption

Consuming excessive amounts of fatty foods does not help trigger ketosis in the body. The key step is to deprive the body of carbohydrates so that it seeks an alternative to yield energy. 

When you withdraw carbs from your diet, the body will begin to utilize fat reserves instead. Once the body enters ketosis, your diet must continue to include scarce amounts of carbs. 

  1. Protein Intake

Protein is a significant food group of the keto diet, but it can delay ketosis if not consumed in moderation. If you include too much protein in your diet, the liver may convert it to glycogen and prevent the onset of ketosis.

An ideal keto meal consists of around 80% fats, 15% protein, and 5% carbohydrates. 

  1. Physical Activity

Physical activity accelerates the number of calories burned per unit of time. When you exert the body, blood glucose is readily used up and fat reserves are next in line.

When our body adheres to derive energy from fats instead of carbohydrates, it can then easily enter ketosis. People who remain physically active at all times have a higher metabolic rate, which further encourages the breakdown of fats.

  1. Age

Youngsters are more active than old people, which is why they are able to enter ketosis in less time. Younger people also have a bigger appetite and a higher metabolic rate, so it makes sense that their bodies can enter ketosis relatively quickly. 

That being said, the keto diet is safe for all age groups, and your body can get used to ketosis even if you’re fifty. Aging may slow down the process to some extent, but an energetic routine can make up for it. 

  1. Lack of Sleep

Lack of sleep disrupts hormonal balance, impairs blood sugar control, elevates cortisol levels (stress hormone), and drains energy for physical activity. As a result, our cognitive functions decline, and we crave carb-rich foods.

People who sleep 7-8 hours at night are healthier and happier. They wake up rejuvenated, make better food choices, and undergo greater physical exertion. Therefore, it is safe to say that adequate sleep enhances metabolism and ultimately expedites ketosis. 

Why Do Some People Take Longer to Enter Ketosis?

Different combinations of factors discussed above influence how long it takes to enter ketosis. Moreover, every person’s metabolism is unique, and their genetics can be partially responsible. 

If you previously relied on a carb-rich diet, you might need more time to enter ketosis as opposed to someone accustomed to a low-carb diet. This is to be expected because your body first needs to deplete its glucose reserves and then adapt to burning fat. 

Individuals who shift from a high-protein diet to keto also take longer to enter ketosis for similar reasons. It’s all about who you were before and what you’re doing now to bring a change. 
There is no standard answer for how long it takes to get into ketosis. An athlete will require less time to enter ketosis as compared to an office clerk. This is because the clerk sits at their desk most of the time while the athlete constantly exercises their body and develops a higher metabolic rate.

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. 


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.