Home  /  All  /  Lifestyle  /  Science

Getting into Ketosis: Everything You Need to Know

Written by
  Published on September 17th, 2020
  Reading time: 4 minutes
  Last modified March 7th, 2022
getting into ketosis

Getting into ketosis is a process that varies for everyone. Some get into ketosis quicker than others, and some experience a smooth shift of metabolism, while others end up with the keto flu.

So, what exactly is ketosis? How long does it usually take to get into ketosis? What is the keto flu, and how can you avoid it? Here’s everything you need to know about getting into ketosis.

What is Ketosis?

Ketosis is a natural state of metabolism that can be advantageous for your health. Put simply, ketosis involves your body producing ketone bodies out of fat and using those as the primary fuel source instead of carbohydrates.

You can get into ketosis by following a low-carb, high-fat ketogenic diet. When there’s limited access to glucose (blood sugar), your body goes into ketosis [1]. Ketosis can also happen during other circumstances, such as fasting, starvation, and pregnancy [2,3,4,5].

How Does Ketosis Work

To reach the metabolic state of ketosis, most people need to consume fewer than 50 grams of carbs per day and sometimes less than 20 grams per day. This means removing certain food items from your diet that would exceed your carb count, such as processed, refined grains and sugary soft drinks. Read our helpful article for more info on what to eat on a ketogenic diet.

When you’re eating a low-carb diet, insulin hormone levels decline, and your body releases fatty acids from your fat stores in large amounts. Many fatty acids are transferred to your liver, where they’re turned to ketones (ketone bodies). Ketones can provide your body with energy. Ketones can also cross the blood-brain barrier and provide energy for your brain when there isn’t any glucose.


What is the Keto Flu?

As you transition into ketosis, you might experience certain symptoms, known as the keto flu. These symptoms include fatigue, headaches, and increased thirst. The good news is that you can avoid or diminish these symptoms by replenishing electrolytes, staying hydrated, etc. For more on this, read our helpful article.

keto flu

How Do You Know if You’re in Ketosis?

You might have symptoms of the keto flu, which lets you know you’re transitioning into ketosis. If you’re lucky enough not to experience these symptoms and you’re keeping it low-carb, high-fat, eating good quality keto food, and feeling good, you’re probably in ketosis.

How Long Does It Take to Get into Ketosis?

How long it takes to reach ketosis depends on the individual, and some people take longer than others. To get the ketogenic diet benefits, you have to be in the metabolic state of ketosis.

Generally speaking, it usually takes 2-4 days if you consume 20-50 grams of carbs per day to reach ketosis. For some people, it takes a week or longer. If you’re not as metabolically adapted, it will likely take you longer to enter ketosis [6,7,8].

Some factors affect how long it takes to reach ketosis, such as your daily intake of fat, carbs, and protein, and your age, metabolism, and exercise level.

Those who usually eat a higher-carb diet might take longer to enter ketosis than those who generally consume a low-to-moderate carb diet. Your body also needs to deplete glycogen stores (stored glucose in the muscles) before entering ketosis [9].

The best way to tell if you’re in ketosis is to test your body’s ketone levels. You can measure certain types of ketones, such as acetoacetate and beta-hydroxybutyrate. Different types of tests are available, such as breath, blood, and urine. Read our article for more info on testing ketones [10].

Do You Test Your Ketones?

Are you in ketosis? What have you experienced as you transitioned into ketosis?


1.    Freeman, J. M., Kossoff, E. H., & Hartman, A. L. (2007). The ketogenic diet: One decade later. Pediatrics119(3), 535-543. DOI: 10.1542/peds.2006-2447

2.    Wu, P. Y., Edmond, J., Auestad, N., Rambathla, S., Benson, J., & Picone, T. (1986). Medium-chain triglycerides in infant formulas and their relation to plasma ketone body concentrations. Pediatric Research20(4), 338-341. DOI: 10.1203/00006450-198604000-00016

3.    Cunnane, S. C., & Crawford, M. A. (2003). Survival of the fattest: Fat babies were the key to evolution of the large human brain. Comparative Biochemistry and Physiology136(1), 17-26. DOI: 10.1016/s1095-6433(03)00048-5

4.     Fukao, T., Lopaschuk, G. D., & Mitchell, G. A. (2004). Pathways and control of ketone body metabolism: On the fringe of lipid biochemistry. Prostoglandins, Leukotriens, and Essential Fatty Acids, 70(3), 243-251. DOI: 10.1016/j.plefa.2003.11.001

5.    Owen, O. E., Felig, P., Morgan, A. P., Wahren, J., & Cahill Jr, G. F. (1969). Liver and kidney metabolism during prolonged starvation. Journal of Clinical Investigation48(3), 574-583. DOI: 10.1172/JCI106016

6.    Scott, J. M., & Deuster, P. A. (2017). Ketones and human performance. Journal of Special Operations Medicine17(2), 112-116.

7.    Harvey, C. J., Schofield, G. M., Williden, M., & McQuillan, J. A. (2018). The effect of medium chain triglycerides on time to nutritional ketosis and symptoms of keto-induction in healthy adults: A randomized controlled clinical trial. Journal of Nutrition and Metabolism, 2630565. DOI: 10.1155/2018/2630565

8.    Harvey, C. J., Schofield, G. M., & Williden, M. (2018). The use of nutritional supplements to induce ketosis and reduce symptoms associated with keto-induction: A narrative review. Peer J, DOI: 10.7717/peerj.4488

9.    Masood, W., Annamaraju, P., & Uppaluri, K. R. (2020). Ketogenic diet. StatPearls Internet. https://www.ncbi.nlm.nih.gov/books/NBK499830/

10. Urbain, P., & Bertz, H. (2016). Monitoring for compliance with a ketogenic diet: What is the best time of day to test for urinary ketosis? Nutrition and Metabolism13, 77. DOI: 10.1186/s12986-016-0136-4

Leave a Comment

Your email address will not be published.

Never miss out on exclusive content and limited deals.

As a Member, you get instant access to personalized meal plans, exclusive videos & articles, discounts, a 1 on 1 Coaching Session, and so much more. As a member, you join our mission of empowering 1,000,000 people to positively change their lives throughout the world. Get started today.


A Great Deal
$ 19
99 /month
  • 7-Day Free Trial
  • Cancel Anytime


3 Months Free
$ 179
  • 3 Months Free
  • Cancel Anytime


Membership for Life
$ 349
  • Lifetime Access
  • Limited Availability