Keto Adaptation: How Long Does It Take?

The length of time it takes to keto-adapt depends on several factors, including the method used to enter ketosis, the individual's diet, and their level of physical activity.

For those on a ketogenic diet, it can take anywhere from three to twelve weeks to become keto-adapted. During this time, it is important to stick to clean whole foods and avoid cheats or deviations from the diet. The process can be divided into two phases: the initial carb withdrawal phase, which typically lasts from three to fourteen days and is characterised by cravings, hunger, and possibly the keto flu, followed by the second phase, where the body adjusts from relying on glucose to fat for energy, which can last from six to eight weeks.

However, it is important to note that the time frames mentioned above may vary depending on individual factors and the specific definition of keto-adaptation used. Additionally, there are other methods to induce ketosis, such as exogenous ketone supplements, which can result in a rapid increase in blood ketone levels within minutes to hours.

Carb withdrawal

During the first three days of carb withdrawal, it is common to experience cravings for carbs and to feel discomfort. This is likely due in part to a strong psychological component, as people miss their favourite high-carb foods.

In the following days, people may experience what is known as a "low-carb crash" or "keto flu". This is when the body's glucose reserves are used up, but the body has not yet adjusted to getting energy from fat and protein. Symptoms of the low-carb crash include feeling shaky or jittery, and a general feeling of being unwell, both physically and mentally.

To help alleviate the symptoms of carb withdrawal, it is recommended to focus on consuming fibre and fat, as these produce a high degree of satiety. Eating plenty of water and staying hydrated is also important, as the body naturally loses water during carbohydrate withdrawal. Increasing electrolytes, especially sodium, potassium, and magnesium, can also help.

The good news is that the discomfort of carb withdrawal usually goes away within a few days. However, it is important to listen to your body and make adjustments as needed. For example, if you feel shaky or fatigued, try eating a serving of low-carb fruit, and if the feeling goes away, you may need to include a bit more carbohydrate in your diet.

Overall, carb withdrawal is a normal part of the process when starting a low-carb diet, and with some preparation and patience, it can be successfully navigated.

Ketone production

During ketosis, the liver produces ketones, which are water-soluble molecules. Ketones are produced when the liver metabolises fats, particularly when carbohydrate intake is low. The body can use ketones as an alternative source of energy, and most tissues in the body, including the brain, can use them for fuel.

There are three types of ketone bodies produced by the body: beta-hydroxybutyrate (BHB), acetoacetate (AcAc), and acetone. BHB is the most prevalent ketone body in the circulation. The traditional marker for ketosis is when blood ketone levels of BHB are greater than 0.5 millimolar (mM). This can be measured using a blood ketone meter, similar to a blood glucose meter.

During the transition to keto-adaptation, the body goes through several changes to increase ketone production or utilisation. These changes include increased fat burning, conservation of glycogen, and making more ketones available for the brain. These metabolic adaptations usually occur within 3-4 weeks, but the full benefits of keto-adaptation may take longer to be realised.

Ketone measurement

There are several ways to measure ketones in the body. The most common methods are blood tests, urine tests, and breath tests.

Blood Tests

Blood tests are the most accurate way to measure ketone levels. They involve using a blood ketone meter, similar to a blood glucose meter, to measure the concentration of beta-hydroxybutyrate (BHB), the predominant ketone body, in the blood. Blood tests give accurate readings of current ketone levels and are less messy to use compared to urine tests. However, they are more expensive, require a machine meter, and may not be covered by insurance.

Urine Tests

Urine tests are a cheaper and more convenient option, as they can be purchased without a prescription and easily carried around. Urine ketone test strips can be placed directly into a urine sample or held under the urine stream. The strip will change colour, indicating the ketone level based on the provided chart. However, urine tests only show ketone levels from several hours ago and may not be accurate if the person is dehydrated.

Breath Tests

Breath tests use a handheld device, similar to a breathalyzer, to measure acetone levels in the breath. This method is non-invasive and easy to use but is less accurate than blood or urine tests, providing only a rough estimate of ketone levels.

Interpretation of Results

The interpretation of ketone test results can vary depending on the test used and individual factors. In general, a normal ketone level is considered to be less than 0.6 millimoles per liter (mmol/L), with higher levels indicating moderate to very high ketone concentrations. People with diabetes or those at risk for diabetic ketoacidosis should monitor their ketone levels regularly and seek medical attention if levels become moderately high or very high.

Ketogenic diet

The ketogenic diet is a high-fat, low-carb diet that restricts carbohydrates and promotes a moderate protein intake. Typically, someone on a keto diet will get about 80% of their calories from fat, 15% from protein, and less than 5% from carbohydrates (no more than 50 grams per day).

The goal of the keto diet is to reach a state of ketosis, where the body breaks down fatty acids to form ketone bodies for energy. This metabolic state can be achieved through several means, including low-carb diets, exercise, and fasting.

Given the lack of long-term research on humans and the ketogenic diet, there is no precise answer for how long keto-adaptation takes. While ketosis can be achieved after a few days of fasting or a ketogenic diet, keto-adaptation may take longer, possibly up to a month or more. This is because the body's ability to utilise ketones doesn't increase at the same rate as the levels of ketones in the blood.

Signs of Keto-Adaptation

There are several signs that indicate your body has adapted to the ketogenic diet:

• Stable energy levels throughout the day
• Reduced cravings and hunger
• Increased endurance and physical performance
• Weight loss and reduced body fat
• Improved mental clarity and focus

Fat-Adaptation vs. Ketosis

It is important to distinguish between fat-adaptation and ketosis. Ketosis refers to the production of ketones, which can happen overnight. In contrast, fat-adaptation occurs when your body has fully shifted to burning fat as its primary fuel source and can take a month or more. This is a long-term metabolic transition where your body becomes more efficient at metabolising fat as its main energy source.

Ketosis benefits

Benefits of Ketosis

Weight Loss

Ketosis is a metabolic state in which the body uses fat as its main source of energy. This can lead to weight loss as the body breaks down fatty acids to form ketone bodies for energy. Low-carb diets are an effective way to lower blood pressure and reduce body weight and fat mass.

Improved Blood Sugar Management

Ketosis can help manage blood sugar levels and reduce the need for insulin in people with type 2 diabetes. It may also help prevent or manage type 2 diabetes by reducing insulin resistance.

Reduced Seizures in Children with Epilepsy

Ketosis has been shown to reduce seizures and sometimes even cause remission in children with epilepsy. The ketogenic diet has been used as a treatment for epilepsy for decades and can be an effective alternative to drug treatment.

Improved Lipid Profiles

Ketosis can improve lipid profiles by lowering low-density lipoprotein (LDL) (also known as "bad" cholesterol), increasing high-density lipoprotein (HDL) (also known as "good" cholesterol), and lowering triglycerides. This can lead to a reduced risk of heart disease.

Therapeutic for Several Brain Disorders

Ketosis has been found to have therapeutic effects on several brain disorders, including Alzheimer's disease and Parkinson's disease. Ketosis can increase the levels of ketones in the brain, which can improve brain function and protect neurons from damage.

Increased Energy Levels

Ketosis can lead to increased and consistent energy levels throughout the day. This is because ketones are a more efficient source of energy for the body and brain compared to glucose.

Reduced Cravings and Hunger

Ketosis can reduce cravings and hunger, making it easier to stick to a calorie-restricted diet. This is because low-carb diets lead to an automatic reduction in appetite.

Frequently asked questions