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Achieving a state of ketosis was attractive to me because it reduces hunger, increases satiety, boosts weight loss efforts, and has the potential to reduce risk for certain diseases. Thus far, it has worked wonders for me. I rarely feel hungry, I have a lot more energy and I believe it has improved my mental processing speed. In order for me to be successful with the keto diet, I knew I needed to know more about how to get into ketosis.

Measuring Ketone Levels

You’re feeling good and shedding unwanted pounds, but how do you know that you’ve reached the desired state of ketosis? For techies, there are a few cool gadgets available to measure ketone levels. Blood, urine, and breath measurements can be used to determine whether you’ve entered ketosis.

Blood ketone meters have made measuring ketone levels at home an easy task. These are very similar to blood glucose levels except that they measure ketone levels. You simply prick your finger and then use the ketone measuring strips to soak up the drop of blood. The blood ketone meter will then measure blood ketone levels.[i]

Urine test strips are also simple to use. You basically pee on them or dip them into your urine sample. The strip will change color based on the urine levels of the ketone, acetoacetate. Urine test strips offer an easy and inexpensive method for testing whether you’ve entered into ketosis.  This is what I use and find them to be an easy way to monitor your ketone levels.

Breath testing is a third method for assessing ketosis. A breath ketone meter is a reusable meter that measures breath ketones. There are no blood or urine measurements required, so no strips are involved. It can be charged using a USB port. You simply blow into the meter for up to 15 seconds, and it gives you a reading.

All three methods of ketone measurement methods are easy and straightforward. Instructions come with each, as does guidance regarding how to interpret the results.

How to Get into Ketosis

If your carb intake has dipped below 50 grams per day, it is likely that you have entered, or soon will enter, ketosis. Scientific studies often measure blood levels of the ketone, beta-hydroxybutyrate, to assess the cut-off point for entry into ketosis. Beta-hydroxybutyrate levels of 0.5 mmol/L and above suggest that nutritional ketosis has been reached.

Higher levels are often desired to elicit beneficial effects for seizure control in children who have epilepsy and have also been deemed the ideal goal for weight loss and optimal metabolic functioning. When I started, I went immediately to 15-20 grams/day. I would not advise doing it in this manner. It is just as effective to slowly lower your daily consumption.

That ideal “sweet spot” of ketosis is often defined as a level between 1.5-3 mmol/L. In The Art and Science of Low Carbohydrate Living, researchers Stephen Phinney and Jeffrey Volek recommend this range for full nutritional ketosis and subsequent health benefits. Ketone levels ranging between 0.5-1.5 mmol/L have been described as “light” nutritional ketosis, which is also beneficial – although not to the degree of full nutritional ketosis. The longer one stays in the “optimal ketone zone,” particularly the sweet spot range, the more fat is burned, and weight loss is more effective.[ii]

Various experts have opinions about what is the optimal ketone level. The following table provides a general summary of ketone ranges recommended for several health outcomes. This is meant to serve as a helpful guide, so you can tweak your diet to achieve certain personal goals. It is not meant to substitute for medical advice.

Goal Ketone Levels
Weight Loss Above 0.5 mmol/L
Improved Athletic Performance Above 0.5 mmol/L
Improved Mental Performance 1.5 – 3.0 mmol/L
Therapeutic (i.e. to treat certain health conditions) 3.0 – 6.0 mmol/L

How Long Does it Take to Get Into Ketosis?

Generally speaking, it typically takes two to four days to reach a state of ketosis. However, there are still several factors that will affect how quickly your body will enter a state of ketosis. Age, physical exercise, current metabolic rate, and intake of food are all factors that can improve or delay the rate of which you get into ketosis.

For example, according to Wajeed Masood and Kalyan R. Uppaluri, usually people who consume a high-carb diet could take longer to enter ketosis than those who eat a low-to-moderate carb diet because their body needs to exhaust its glycogen stores before entering ketosis.[iii]

To help you reach ketosis more efficiently so your body can burn stored fat instead of glucose, follow these six tips:

  1. Exercise more
  2. Try intermittent fasting
  3. Eat healthier fats (coconut oil, flaxseed oil, avocado oil, olive oil)
  4. Cut carbs quickly
  5. Keep a high protein diet
  6. Track your food, you must be consistent (understand keto macros)

If you want a quick reference guide on keto-friendly snacks check out our Free Keto Snacks Downloadable.

Potential Side Effects of Ketosis

Many keto dieters report having a dry mouth and feeling unusually thirsty. The state of ketosis is dehydrating and causes water and electrolyte loss. To compensate for the loss, it is important to drink adequate amounts of water and replenish lost electrolytes. My water consumption nearly doubled when I started the keto diet.

Feeling less hungry is also often reported by keto dieters. This is likely due to a change in hunger hormones and results in a dampened appetite. This is a bonus for those who are following keto to lose weight. Similarly, rapid weight loss may be present. In a ketogenic state, the body sheds carbs and water, and the pounds just seem to fall off. For me, this was about 10 pounds per month.

A ketogenic state is often associated with less brain fog and improved concentration. Many keto enthusiasts report improved mental clarity and razor-sharp focus because of ketosis. When carbs are cut, blood sugar levels stabilize. This has a positive effect on the brain and the ability to focus. There is no more crashing and burning, and the mind benefits from this new-found harmony.

On the flip side, it is important to note that side effects of ketosis may ensue, albeit temporarily.  The term keto flu has been coined to describe the short term, flu-like symptoms that occur because of your body’s natural response to carbohydrate restriction. The symptoms of keto flu generally kick in at the 24-48-hour mark after embarking on the keto diet and can last from a few days to upwards of a month at most.

Symptoms may include any or all the following: headache, foggy brain, confusion, dizziness, irritability, fatigue, insomnia, chills, and muscle soreness. I am not sure why, but I did not experience these symptoms. The gradual reduction in carbohydrates will help mitigate these symptoms.
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The keto flu is essentially your body’s way of going through withdrawal. Some keto dieters never experience the keto flu, while others describe it as pure misery. Whether you experience the keto flu is likely driven by a combination of genetics and lifestyle factors, especially previous dietary choices. Those who consumed a highly refined and processed diet are more likely to experience symptoms, while those who consumed a high fiber, minimally processed diet may be exempt from experiencing these unpleasant symptoms.  I was lucky in that I never felt bad, save for craving carbohydrates the first few days.

Multiple shifts in the body’s systems likely contribute to the keto flu symptoms. When carb intake declines, so too does insulin production. This drop sends a signal to your kidneys to flush out sodium. This is the same mechanism that is responsible for the rapid weight drop. For many, the average weight loss is about 10 pounds over the course of several days to a couple weeks.

On the negative side, the glycogen loss and insulin drop may cause nausea, dizziness, headaches, muscle cramping, and GI issues. To overcome these symptoms, proper hydration and electrolyte replacement is recommended.

Thyroid hormone production is also affected by carbohydrate intake. When carbs are cut, the levels of the active form of thyroid hormone, T3, can fall. This may result in a temporary feeling of mental fogginess as the thyroid adapts to carbohydrate restriction. The T3 shift is intimately connected to cortisol (the stress hormone) where a dip in T3 results in elevated cortisol levels. This is because the ketogenic state elicits the same response as starvation. The body senses that it is in a state of stress, and cortisol responds appropriately by rising.

Irritability and insomnia indicate that cortisol has risen. The good news is that this is a temporary state. Once the body adapts to running on ketone-driven fuel, these symptoms should disappear. Individuals with pre-existing thyroid disease or adrenal dysfunction may consider it prudent to discuss lifestyle and dietary changes with their health care provider before embarking on a ketogenic diet.

Digestive issues may also arise as a response to the ketogenic state. Constipation and diarrhea are commonly reported when keto newbies first embark into ketosis territory. This is the body’s natural response to high fat intake and should diminish as the body adapts to a new dietary pattern. Consuming low carb, high fiber vegetables can help to ease these digestive symptoms. Probiotics may also be a useful adjunct therapy to minimize the digestive discomfort.

Lastly, the dreaded keto breath signals that the body has shifted into a state of ketosis. As the body transitions into the ketogenic state, ketones are expelled via the breath. Excess production of the ketone, acetone, is primarily to blame for fruity breath. The upshot is that this is a temporary state and can be easily remedied by sipping on mint-infused water or brushing your teeth more frequently.

Although most people can follow the ketogenic diet with no issues, certain contraindications do exist. The ketogenic diet is contraindicated in patients with the following health conditions: pyruvate carboxylase deficiency (rare genetic disorder), porphyria (buildup of substances called porphyrins in the blood), and fat metabolism disorders. A person who is not able to metabolize fatty acids must rely on carbs as their primary fuel source. If they were to follow a keto diet, their body would be forced to consume protein stores as a source of energy, which may eventually result in a potentially fatal condition called ketoacidosis.

Additionally, as a rule of thumb, any pre-existing health condition warrants a discussion with your health care provider before embarking on a drastic diet or lifestyle changes. Those with autoimmune disease, thyroid disease, or adrenal dysfunction should consult with their doctors before trying keto. Also, anyone who is taking medication for diabetes or high blood pressure should discuss their desire to try keto before they make dietary changes. Women who are pregnant or contemplating pregnancy should wait until after pregnancy or breastfeeding to begin a ketogenic diet.

[i] Bruno Guerci, Muriel Benichou, Michèle Floriot, Philip Bohme, Sebastien Fougnot,Patricia Franck, Pierre Drouin Accuracy of an Electrochemical Sensor for Measuring Capillary Blood Ketones by Fingerstick Samples During Metabolic Deterioration After Continuous Subcutaneous Insulin Infusion Interruption in Type 1 Diabetic Patients Diabetes Care Apr 2003, 26 (4) 1137-1141; DOI: 10.2337/diacare.26.4.1137

[ii] Keto Range Reference:

[iii] Wajeed Masood, Kalyan R. Uppaluri, Ketogentic Diet (NCBI, 2019),