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.
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].
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 more about 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.
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.
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 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].
Are you in ketosis? What have you experienced as you transitioned into ketosis?
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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
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
Masood, W., Annamaraju, P., & Uppaluri, K. R. (2020). Ketogenic diet. StatPearls Internet.
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