How Long Should You Do Keto? How Long It’s Safe To Stay In Ketosis

The keto diet, or ketogenic diet, is a popular weight loss diet and is used to help manage blood sugar and reduce inflammation, though it was originally designed to treat epilepsy.

Keto experts suggest that the keto diet should involve consuming 70–75% of your calories from fat, 20-25% of your calories from protein, and 5% of your calories from carbohydrates in order to put the body in a state of metabolic ketosis.

But, how long should you do keto for? How long is it safe to be in ketosis? Is ketosis dangerous if you do keto for too long? Is keto bad for you long-term? What are the common keto side effects or signs you should quit keto?

In this article, we will discuss how long you should do keto for weight loss or health, whether keto is bad for you or prolonged ketosis is unhealthy, common keto side effects, and signs you should quit keto and give your body a break from the keto diet.

We will look at: 

  • How Long Does It Take to Get into Ketosis?
  • How Long Should You Stay in Ketosis?
  • Is Keto Bad for You Long Term?
  • How Long Should You Do Keto?

Let’s get started!

Keto diet with food surround it like vegetales, fish and nuts.

How Long Does It Take to Get into Ketosis?

The central tenet of the keto diet is to induce a state of metabolic ketosis, which occurs when the body is burning ketones for energy due to severe restriction of carbohydrates.

Because the keto diet limits daily carbohydrate intake to 25 to 50 grams or so, the body has to burn fat for fuel because there is simply an insufficient number of carbohydrates available to burn for energy.

Once the body starts burning stored body fat for fuel or metabolizing dietary fats as they are digested, the liver begins producing ketone bodies as a byproduct of the breakdown of fat.

When your body is producing a lot of ketones in the liver, you are in a state of ketosis.

But, how long does it take to get into ketosis?

Entering ketosis can take as little as 18 hours and as much as 3 to 4 days, depending on your body size, muscle mass, normal dietary habits, whether or not you are consuming any carbs and your training status.

A cutting board with food and the macronutrient breakdown of the keto diet.

Highly-trained endurance athletes have greater glycogen storage capacity in the muscles, so it will take longer to get into a state of ketosis because the body adapts to store more grams of glycogen that must be burned through before you enter ketosis.

Additionally, if you are a larger person and have more muscle mass, you will also be able to store more glycogen, and if you are eating any carbs, it will take longer to get into ketosis because your body will preferentially use the carbs you are eating for energy before dipping into burning fat and producing ketones.

Some keto experts suggest that you can get into ketosis faster if you take medium-chain triglycerides (MCT oil) or coconut oil, which is a great natural source of MCTs.

Additionally, by keeping your carbohydrate intake as low as possible, ideally around 25 to 30 grams per day, you are going to enter ketosis faster because your body will have to burn through your glycogen stores without getting new carbohydrates coming in through the diet.

For example, studies that have looked at the stages of fasting have found that when you are water fasting, which involves consuming absolutely no calories from any food or beverage, you can enter ketosis in as little as 16 to 24 hours after fasting.

Coconut oil.

Another way to expedite the process of entering ketosis is to do an endurance-based workout, high-intensity workout (HIIT), or heavy resistance training weightlifting workout to burn through your glycogen stores and then refuel with only protein, fat, fluids, and electrolytes.

Keep in mind that while this will help you get into a state of ketosis faster because your body will use up most or all of your glycogen in your workout and then will have to rely on burning fat and producing ketones, workout recovery will be compromised if you do not refuel with carbohydrates.

This can increase muscle soreness, delay muscle healing, and potentially compromise muscle protein synthesis and muscle building after strength training.

How Long Should You Stay in Ketosis?

There are weight loss and health benefits of ketosis, such as increased fat burning, faster weight loss, reduction of water weight due to the release of the water stored alongside glycogen, decreased appetite, and sometimes higher energy and mood.

The macronutrient breakdown of the keto diet and different food surrounding it.

Longer-term benefits of ketosis or prolonged ketosis include improved blood sugar management, lower levels of insulin, reduced risk of type 2 diabetes and better management if you already have the condition, and reduced risk factors for heart disease.

However, although there are health benefits of the keto diet and being in ketosis, long-term ketosis and staying on the keto diet for an extended period of time is not recommended by many nutrition and health professionals.

So, how long should you do keto?

The general consensus is that doing keto for six months works well but that you should give your body a break from keto after six months.

After six months, you should gradually introduce more carbohydrates, at least for a temporary period of time, before going back onto the keto diet if you have not yet achieved the weight loss results you are hoping for or the other health benefits that help you feel your best.

This approach is called the cyclical keto diet, in which you follow the keto diet for a defined period of time and then transition off to a more balanced macro diet and then go back to keto.

Food surrounding a notebook that has the words keto diet written on it.

The benefit of this approach is that it not only gives you a mental break from the restrictive nature of keto but also gives your body a metabolic break and helps prevent it from becoming so efficient at using fat and ketones for energy that you no longer lose as much weight on the keto diet.

As with any diet or exercise plan, the body can adapt to the keto diet and to being in a constant state of ketosis, and you can hit a weight loss plateau on keto.

Cycling on and off keto in 3- to 6-month intervals can be a great way to keep losing weight on keto, particularly if you have a lot of weight to lose.

Although it is normal to drop quite a lot of weight in the first couple of weeks of keto due to the release of excess water weight, after that, you should still only be aiming to lose about 1 to 2 pounds per week for sustained and healthy weight loss

Therefore, if you are trying to lose 30, 50, or 100 pounds or more on the keto diet, taking a break from keto every few months can help keep the keto diet working effectively as a great weight loss approach.

The keto diet macro breakdown and an avocado sliced in half.

Is Keto Bad for You Long Term?

Here are some of the potential risks of long-term ketosis and staying on the keto diet too long:

  • Vitamin and mineral deficiencies due to a lack of fruits and vegetables, whole grains, and legumes.
  • Decreased athletic performance because limited glycogen availability can decrease the ability to perform vigorous exercise.
  • Slowed weight loss as the body adapts to the keto diet, and keto dieters get more lax in the grams of carbs and overall calories they are eating.
  • Higher sensitivity to high-carb foods if you have a “cheat day.” Studies have found that having sugary beverages on keto can damage blood vessels because the body becomes less able to handle higher amounts of carbs and sugar.
  • Elevated risk of heart disease if you eat too many unhealthy fats and animal products, though the research is mixed on the risk of diets high in saturated fat and cholesterol.
  • Poor digestion and microbiome disruption because diets high in fatty foods and low in fiber and plant-based foods can alter the composition of the gut microbiota and can cause constipation and an increased risk of colorectal cancer and inflammatory bowel disease.
  • Lower antioxidant levels if you are limiting carbs by minimizing fruit and vegetable consumption. Antioxidants help prevent oxidative damage and support better immunity, cell turnover, decreased inflammation, and better cardiovascular function.

Note that not everyone following the keto diet for a long time will necessarily experience these potential risks of long-term keto.

There have not been studies showing the keto diet is bad for everyone long term.

Rather these are potential risks of the keto diet for those who follow the keto diet for too long in an unhealthy, imbalanced way without medical supervision.

A plate of salad and protein.

How Long Should You Do Keto?

Even though studies have found that counting calories isn’t a very effective way to lose weight or maintain weight loss, if you do come off keto and take breaks from keto, you should be mindful of your caloric intake so that you don’t regain a lot of weight.

However, it is important to remember that you will gain some weight quickly after stopping keto simply because your body will be retaining some water with a higher carb intake. Once you go back on keto and you burn through your glycogen, this water weight should be released.

One advantage of staying on keto in the long term is that studies have found that when people lose a lot of weight, appetite can increase, caloric expenditure can decrease, and they can feel sluggish and tired because the body tries to conserve calories through a process known as adaptive thermogenesis.

If you stay on keto, you might be able to avoid some of the appetite and cravings because you aren’t giving your body excess sugar, and you will continue burning fat for fuel.

Even though there haven’t been super long-term studies about the safety of keto, there have been some year-long studies on the safety and effectiveness of the keto diet for weight loss and health management. 

These studies have found that following the keto diet for a year does not result in adverse health effects and continues to support weight loss, reduces BMI, improves blood sugar management, and lower triglycerides, LDL cholesterol, and glucose levels.

However, if you want to stay on the keto diet for an extended period of time, it is advisable to discuss your keto diet plans with your doctor or a registered dietitian or nutrition professional.

To learn more about some common keto diet mistakes, check out our guide here.

Salmon stuffed avocado.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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