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Following my recent post about carbohydrates, I've put together what I consider to be the most important facts about ketosis and measuring ketone bodies.

Ketosis vs. Ketoacidosis Ketosis is a state in which your liver produces ketones at an accelerated rate, shifting the body's metabolism away from glucose and towards fat utilisation. The presence of ketones in your body, which is indicative of lipolysis, is a definite proof of ketosis. According to Volek and Phinney in their best-selling book "The Art and Science of Low-Carbohydrate Living", nutritional ketosis is defined by serum ketones ranging from 0.5 to 3.0 mM. The frequently asked question is whether ketosis is dangerous. Ketosis is not only a great weight loss tool, but it has been used for treating or managing diseases such as epilepsy, Alzheimer's and even cancer. You can check out my post here to see more about health effects of ketogenic diets with links to relevant research. While nutritional ketosis is perfectly safe, ketoacidosis is an indicator of serious health problems. Ketoacidosis occurs in serious health conditions such as type 1 and type 2 diabetics and alcoholics and has nothing to do with nutritional ketosis. The levels of ketones in ketoacidosis are 3-5 times higher than in ketosis resulting from a ketogenic diet.

4 Ways to Measure Ketones There are three types of ketone bodies: Acetone, Acetoacetate and Beta-Hydroxybutyrate (BHB). Unlike protein intake, where the daily amount is determined by your lean mass weight, the amount of carbs to enter ketosis can be estimated using: 1) Blood ketone meter It's the most accurate way to measure BHB ketone bodies. The level of BHB in your bloodstream will tell you how much you have in your fuel tank but it will not measure the metabolic usage of ketones. Typically, this happens when you have started following the ketogenic diet and are not yet fully keto-adapted. Blood ketone meters can precisely determine the level of ketones in your blood but they are also pricey. To give you an idea, the meter itself is about $40 and the test strips cost $5 each. If you want to test yourself daily, it will cost you $150 per month plus the cost of the meter. I don't know about you but I'd rather spend it on quality food or a gym membership. On the other hand, if you are on the Restricted Ketogenic Diet and numbers matter to you, a blood ketone meter may be the best and only option you have. 2) Breath testing - "Breathalyzer" According to Volek and Phinney in The Art and Science of Low-Carbohydrate Living (chapter 13, Ketones - To Measure or Not), a non-invasive and cheap alternative is to measure breath acetone concentration. Acetone is one of the ketone bodies that results from a break down of acetoacetate. The level of acetone will reflect the metabolic usage of ketones. The Ketonix Acetone Breathalyzer is available and offers an easy and inexpensive way to test your breath ketones (acetone). Keep in mind that breath ketones do not always exactly correlate with blood ketones and are affected by several factors (alcohol consumption and water intake). You can find my review of the breathalyzer here. 3) Urine ketone strips Ketostix, Uriscan and other urine detection strips are not as accurate. They only measure the level of acetoacetate - excess ketone bodies that are not utilised by the body and are excreted via urine. Urine ketone strips can still be useful during the initial phase of the ketogenic diet when you simply want to test the level of carbohydrates in order to enter ketosis. Some people use them to test if they are sensitive to certain foods that may be keto-friendly but still have a negative effect on their progress. They are easy to use and fairly cheap. You'll pay about $10 for 50 strips, that's $6 a month if you test yourself daily. If urine detection strips don't work for you, use one of the other two methods. 4) Observation Listening to your body's signals is another way of finding out whether you are in ketosis. When your body is in ketosis, you may smell of acetone. This could be sensed in your breath, sweat or urine. Some people refer to this as ketogenic "fruity" smelling breath or "keto breath". If you detect any of these signs, you are more than likely in ketosis. Bestselling Keto Books Keto Chaffles Order and get 5 bonus chaffle recipes! My latest keto cookbook! 75 Delicious Treats for Your Low-Carb Diet Chaffles are the epitome of simplicity and versatility Simple Keto Meal-prepping, planning, and shopping strategies 100+ delicious low-carb recipes Quick & easy, no stress, no complication The Beginner's KetoDiet Cookbook Easy keto guide 100+ delicious low-carb recipes Whole foods, optimized for nutrition The Keto All Day Cookbook My best keto recipes 100+ delicious low-carb recipes Allergy-free options Quick Keto Meals in 30 Minutes or Less Quick and easy meals 100+ delicious low-carb recipes Allergy-free options Sweet & Savory Fat Bombs Sweet treats & savory snacks 100+ delicious keto recipes Allergy-free options Keto Slow Cooker & One-Pot Meals 100+ delicious low-carb recipes Ideal for batch cooking and meal prep Allergy-free options The KetoDiet Cookbook 150+ delicious low-carb recipes Quick guide to keto Keto food list Super Low-Carb Snacks 100+ delicious low-carb recipes Tasty paleo treats and snacks Ultra low-carb fat bombs Get it now Have any of my books? Claim your Premium Diet Plans

Why are Ketostix Inaccurate? As mentioned above, although your body may produce ketone bodies which you can measure in your blood stream, Ketostix only show excess ketone bodies excreted via urine. These excess ketones are, in fact, wasted calories. Below are the main reasons for different level of ketone bodies in your blood and urine: Ketostix don't measure all types of ketones produced by your body. Although there are 3 types of ketones (acetone, acetoacetate and beta-hydroxybutyrate), they only measure acetoacetate. Depending on how long you have been in ketosis, your body produces different types and amounts of ketones and you may not be able to detect acetoacetate when keto-adapted. For more details, check out this post at Ketopia.com.

As you become keto-adapted (3-4 weeks), you will excrete less ketone bodies via urine. This means that you may show high blood ketones and low or no urine ketones.

Also, changes in hydration affect the concentration of ketones. A high water intake may dilute the concentration of ketones in the urine. Because it's important to stay hydrated, you will likely see lower readings.

Other reasons (fluctuations that appear after waking up, after eating and post-workout)

More Ketones, More Fat Loss? Most people believe that in order to lose as much fat as possible, they need to restrict their carbs intake as much as they can. I've already explained the main effects of a low-carb, ketogenic diet. Currently, it's not clear what the full effect of such carbs restriction is. Some diet authors, including Atkins himself, supported the idea that more ketones equals more weight loss. The reasoning they gave was that ketones are, in fact, calories which are made from the breakdown of fat in the liver. Is that really a valid reason? Although some fat loss may appear as a result of a potential "metabolic advantage" (more ketones / calories excreted), the most important factor for fat loss is natural appetite control. While urinary ketone excretion means that calories are being lost, the effect is minimal: Based on recent studies, the number of calories lost in the urine as ketones is not significant (100 kcal at most). Anecdotally, higher levels of ketones may actually slow down fat loss. Individuals who maintain lower ketone levels (trace ketones) appear to lose fat more efficiently. Why does that happen? One explanation may be that high levels of ketones in the bloodstream may slightly raise insulin and block the release of free fatty acids from fat cells. Also, when becoming keto-adapted, some individuals tolerate relatively greater carbohydrate intakes without disrupting ketosis. It's up to you to find your optimal carbs intake. As I've explained above, high ketone levels won't help you burn significantly more calories - no studies show such effects. As long as you stay in nutritional ketosis (0.5 to 3.0 mM), moderate amounts of carbohydrates can be added to your diet. If you want to know more about ketone levels and their effect on fat loss, have a look at this post: Do Ketones Matter?

Don't Focus Just on Ketones, See the Big Picture Recently, I've noticed a growing obsession when it comes to measuring ketones precisely. Although urine detection strips may not be accurate for keto-adapted people, they work for most of those that have just started the ketogenic diet. By the time they become keto-adapted, which takes 3-4 weeks, most of them understand what to eat and what to avoid without any real need to measure the precise level of ketone bodies. I've been in nutritional ketosis on and off for almost two years and can't really complain about urine strips. I don't personally need to track exact numbers because it won't make a difference to me. When I started, I used Ketostix to find out when I was in ketosis and what my net carbs limit should be. These days, my daily net carbs intake varies from 30 to 60 grams depending on how active I am. My advice is that you should give Ketostix a try. If you need to keep track of your ketone levels, use a blood ketone meter or the breathalyser. In the end, what really matters is not ketones but the effects of low-carb diets: weight loss and improved health.

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Martina Slajerova Creator of KetoDietApp.com I changed the way I ate in 2011, when I was diagnosed with Hashimoto’s, an autoimmune disease that affects the thyroid. I had no energy, and I found it more and more difficult to maintain a healthy weight. That’s when I decided to quit sugar, grains, and processed foods, and to start following a whole-foods-based ketogenic approach to food. More posts by Martina Slajerova Martina Slajerova About the Reviewer This article has been reviewed by Franziska Spritzler, RD, CDE who is a qualified expert. At KetoDiet we work with a team of health professionals to ensure accurate and up-to-date information. You can find out more on the About us page.