Nutritional ketosis is achieved when there are levels of ketones in the blood, breath, or urine. So it makes sense that measuring ketones is the standard way to figure out whether you’re in ketosis. It’s not the only way, through—which I’ll get to in a moment. But first, a quick clarification: although we often use the terms interchangeably, there’s actually a difference between being fat-adapted and being in nutritional ketosis. When you’re fat-adapted, your body prefers fat to glucose. It has ramped up the enzymatic processes it needs to burn fat as energy and feel comfortable doing so. Once you’re fat-adapted, it’s possible to slip in and out of ketosis while remaining fat-adapted.
When you’re in ketosis, your body is creating moderate levels of ketones by burning fat. So how can you be in ketosis without being fat-adapted? If your body isn’t used to burning fat, it still prefers glucose as an energy source—even if there are ketones circulating in your blood because it has to burn fat. You’re only fat-adapted once your body has made the switch to prefer fats. Here’s one way to think of it: after being in ketosis consistently for three to five days, your body may be in ketosis, but it has yet to become fat-adapted. After three to five weeks, your body will be in ketosis and has probably become fat-adapted.
Having a carb-up, for instance, may reduce the level of ketones in your blood for a brief period, but it won’t change the fact that your body prefers burning fat to burning glucose. As we discuss how to determine whether you’re in ketosis, keep in mind that you don’t have to worry about testing, monitoring, or tracking in order to achieve ketosis. If you’re eating a lot of fats and few carbohydrates, you will likely get into ketosis just fine. But it can be helpful to know your numbers when you’re working toward ketosis for the first time.
Testing for Ketones
Ketone bodies can be found in your urine, breath, and blood, and there are instruments for measuring levels of ketones in each. Each tool measures a different type of ketone body. Testing isn’t strictly necessary, but it can be helpful. When I started out on keto, I tested my blood ketones once per day at various times of day, recorded my results, and made a hypothesis each time about why my ketone level had increased or decreased. I did this for thirty days, which was enough to collect a bunch of ideas about what increased and decreased my ketone level. I don’t test my ketones anymore because I know what nutritional ketosis feels like. When I’m on the mark, I’m good to go. When I don’t feel it, I know where I fumbled and what to do to get it back—and I have all that information because I tested my blood for those first thirty days.
However, it’s worth noting that more ketones don’t necessarily equate to increased fat loss. Say, for example, you eat copious amounts of fat: enough that you’re in ketosis and registering ketones, but too much to allow your body to burn its own fat stores. In this case, dietary fat is the energy source, not your body fat. The most important factors in natural fat loss are appetite balance, metabolic healing, and supporting yourself with positive behaviours.
Tests for: beta-hydroxybutyrate
Testing the blood for ketones is the most reliable and accurate approach. It’s also the most expensive. The reusable meter costs about £28, and the one-use test strips range from £1 to £4 each. If you test twice daily, that’s up to £240 a month just for test strips, not including the cost of the meter. My favourite blood ketone meter is the Precision Xtra Blood Glucose & Ketone Monitoring System from Abbott, available at most drugstores. It lets you test both your blood glucose and ketone levels at once. When you measure your blood ketones, you’re looking for a result of 0.5 to 3.0 mmol/l—any number in this range means that you’re in ketosis.
There is no need to go higher than 3.0 mmol/l; when my clients have a number higher than 3.0, it’s often because they are not eating enough food or they’re dehydrated. If you’ve tested in the morning, before eating, and your ketones have been above 3.0 mmol/l for a couple of days, please eat and/or drink more! You know that you’re in ketosis when your number is between 0.5 and 3.0 mmol/l. Your body is producing significant levels of ketones by burning fat. You know you’re well on your way to becoming fat-adapted when your numbers have consistently been between 0.5 and 3.0 mmol/l for three to five days.
If you’re interested in starting a carb-up practice, it’s generally best to wait until either your ketones have registered between 0.5 and 3.0 mmol/l for five to seven days or you’ve been following the Classic Keto Fat Fueled Profile for ten to fifteen days, whichever happens later. Often these two things happen at around the same time.
Tests for: acetone (resulting from the breakdown of acetoacetate)
Testing the breath for ketones is reliable for most people, much more cost-effective than blood testing, and far more accurate than using urine strips. The best reusable ketone breath meter is made by a company called Ketonix. Their meter can be used multiple times and doesn’t require extra strips; it’s a one-time cost of £149 to £169, depending on the model you choose. To test, you simply breathe out naturally at a slow and steady pace for fifteen to thirty seconds. The tool will take a couple of moments to register a reading, flashing different coloured lights. The key to the success with the Ketonix meter is, when you first purchase it, to sit with it for about an hour and take a measurement every fifteen to twenty minutes, until the values are within the same range.
This lets you work on your testing technique: how you blow into the device makes a difference in how the results are interpreted, so developing a technique and sticking to it will ensure that you’re comparing apples to apples each time you test. Note that your blood and breath ketones will likely not correlate because breath ketones can be influenced by many factors, such as water and alcohol intake. A Ketonix Breath Ketone Analyzer indicates the level of ketones present by displaying a colour: blue for no or very little ketones, green for trace amounts, yellow for moderate amounts, and red for high amounts. The newer models also indicate the level of ketones within each colour by flashing from one to ten times. For example, it could flash ten times with a green light; that means you’re at the high end of the trace group, one flash away from being in the yellow group (moderate amounts).
Tests for: acetoacetate
Testing the urine for ketones is the least accurate testing method. The problem is that it only detects excess ketone bodies that are excreted through the urine. As you continue to become keto-adapted, your body will likely become more efficient at using ketone bodies and therefore won’t excrete as many into your urine. When this occurs, you may experience a drop in urine ketones, but if you measure blood or breath ketones, you’ll see that you’re still in ketosis. If you decide to test your urine for ketones, the presence of ketones is indicated when the test strip changes colour.
The darker the colour, the higher the ketones. The strips group levels together into the trace, small, moderate, and large. The highest level you can test for with many ketone strips is “large” at 160 mg/dL, and this would result in a deep purple, eggplant colour.
An Alternative to Testing
If measuring your ketones isn’t something you want to spend your time or money on, you can gauge where you are by looking at the signs that you’re fat-adapted. This won’t tell you how many ketones are circulating in your body, but it will tell you if your body is using fat as its preferred fuel—which is a good sign that you’re in ketosis. If you have three or more of the signs listed below, it’s likely that you’ve made the switch and are fat-adapted:
- You can skip meals without getting angry.
- It’s easy to go three, four, or five hours without a snack.
- You don’t get ravenous or crave carbs two to three hours after your last meal.
- You crave high-fat foods over high-carb foods.
- You don’t need carbs to push through exercise plateaus.
- You experience steady energy throughout the day without afternoon crashes.
- Your thoughts seem clearer and more focused.
- You no longer experience keto flu.
If you’re interested in starting a carb-up practice, wait until you exhibit three or more of these signs. Generally, that happens after about ten to fifteen days on the Classic Keto Fat Fueled Profile. If you’ve started your journey with carb-ups right off the bat, say with the Daily Fat Burner Fat Fueled Profile, eliciting these signs can take thirty days or more.
When we talk about eating keto, we’re talking about eating fat. Like, a lot of fat. Probably more than you’ve ever dreamed of eating, and then about 10 % more than that.
But before we get to how and why that works, let’s run through the basics. Fat, protein, and carbohydrates are all macronutrients, or “macros,” and they make up the bulk of our food. (The rest is micronutrients—vitamins and minerals that are essential for health.)
Carbohydrates are most abundant in grains and sugars—bread, pasta, rice, corn, quinoa—but fruits and vegetables also contain carbohydrates, especially starchy vegetables like potatoes and sweet potatoes and high-sugar fruits like bananas. Proteins are found in animal foods like eggs, beef, fish, chicken, and turkey and in moderate quantities in some plant foods, such as beans, lentils, nuts, and seeds. Fats are abundant in coconut oil, avocados, olives, nuts, and seeds and animal foods such as ribs, steak, bacon, and dairy.
I used to be a low-fat, high-carb vegan. I remember exactly how little fat I ate and how scared I was of it. I’m guessing that many of you are right there with the old me. But if what you’re doing isn’t working, you’re in a fine place to try something new. Something like the keto diet.
When I first saw the word keto, I was totally intrigued. It sounded foreign, somewhat rebellious. And as you’ll read further on, I love being rebellious, so I was instantly hooked. Keto is short for ketogenic, an eating style that reduces carbohydrate intake, increases fat intake, and moderates protein intake in order to achieve a metabolic shift known as ketosis.
Right now you are burning glucose for energy (unless you’re eating ketogenic already, in which case, total win!). Your body is primed to use energy from the limited glucose in your body, so when that starts to get used up, you become hungry and need to eat again. When I was a glucose burner, I ate every three hours, and the word hangry was at the top of my personal dictionary. I packed snacks to take with me, worried about where my next meal would come from, and would (lightly) budge people in line if it meant I’d get food sooner. Food ruled my life.
What the ketogenic diet does is switch the body from burning glucose to burning fat. This is the primary source of fuel for the body, it’s known as being in ketosis. Now that I’m in ketosis, my daily energy requirements are primarily met by burning fat, so I don’t need to get glucose from the bread, cookies, dried fruits, and treats I used to eat constantly.
My body doesn’t need glucose to survive, and yours doesn’t either! I’ve jumped off the roller coaster of blood sugar highs and lows, and I’m living the good life free from constant snacking, epic weight gain, and uncontrollable cravings. You can, too! There’s tons of room at the keto table for you. Pull up a seat!
Ketosis is not Ketoacidosis
When we talk about being a fat burner, we’re talking about nutritional ketosis, not ketoacidosis. Ketoacidosis is a dangerous condition experienced by diabetics when blood glucose and ketones rise to extremely high levels at the same time. A ketogenic diet won’t get you even close to the levels of ketones that diabetics can experience in ketoacidosis. In fact, if you do not have diabetes, it’s virtually impossible for you to go into ketoacidosis. Even a trace amount of insulin will keep ketone levels in the safe zone.
The level to which carbohydrate intake has to be reduced in order to get into ketosis varies greatly from person to person depending on enzymatic processes, stress level, heritage, and more. (We’ll get into the nitty-gritty of macro ratios and how you know when you’re in ketosis in the next couple of chapters.) But regardless of where you’re coming from, even if you don’t want to go balls to the wall, I’ll outline how you can benefit from increasing your fat intake and dance on the edge of ketosis without macro and calorie tracking running the show.
There are many forms of ketogenic eating. I’m going to be introducing you to the whole-food-based form that’s rich in health-promoting foods and fats. Think of it as a Paleo eating style, jacked up on fats and with way fewer sweet potatoes and chocolate treats and way less maple syrup. You will radically lower your carbohydrate intake, massively increase fat, and moderate protein, a triple whammy that triggers your body to start burning fat for energy rather than glucose.
What Happens in Your Body When You Eat Keto
To explain why the keto diet is so great for health, I want to start by explaining how the body functions on carbohydrates—which is probably the way your body is functioning right now. Carbohydrates from any source—fruits, vegetables, grains, sugars, anything starchy—are broken down into glucose, which is used for energy.
When you have more glucose than you need immediately, your body stores the excess in the liver and then the muscles as glycogen. This is the body’s first-line energy stockpile of fuel for short-burst physical efforts and for keeping certain systems (the brain, red blood cells, kidney cells) running efficiently all day. The glycogen stores in the liver can be utilized by the rest of the body, but the glycogen in muscles is reserved for action in that particular muscle. When space for glycogen in the liver and muscles is full, glucose is converted to fat.
Glucose is the first source the body goes to when it needs energy. But because we can store only a couple thousand calories of glucose (or glycogen when it’s stored) at any given time, it’s not a sustainable source of energy. Also loosing weight is not just about calories. That means we need to keep replenishing it by eating constantly throughout the day. And relying on glucose can prevent us from stabilizing our blood sugar, which spikes when we eat and then drops, resulting in endless cravings and overall weight gain. In addition, glucose can be converted to not just stored fat but also triglycerides in the blood, which can be a risk for heart disease. You’ve also probably heard a lot about insulin, insulin resistance, and insulin sensitivity—all can be negatively impacted when relying on glucose for fuel.
Insulin is the hormone that balances blood sugar; it triggers the absorption of glucose by the liver, fat, and muscle cells and thereby lowers the level of glucose in the bloodstream (blood sugar). Insulin also pauses any fat-burning that’s going on so that we can burn or store the glucose that’s coming in. Once glucose is handled, insulin levels drop and we go back to burning fat. Insulin also alerts the brain if we’re in need of fuel, which triggers hunger signals. When we have good insulin sensitivity, all of these processes work perfectly, maintaining healthy blood sugar stability. But problems arise when glucose levels in the blood are constantly high.
The correspondingly high levels of insulin cause the insulin receptors on cells to become deaf to insulin. Think of the boy who cried wolf: he cries and cries, so all the townspeople stop listening to his warnings. In the case of insulin resistance, cells no longer listen to insulin’s instruction to absorb glucose, so glucose levels in the bloodstream can get and stay too high. But when things are functioning as they should, when the concentration of glucose in the bloodstream falls too low, a hormone called glucagon is released. It stimulates the liver to convert stored glycogen into glucose, which is then released into the bloodstream. It also tells the body to start using the stored fuel source, fat.
Burning fat for fuel is called lipolysis; technically, during lipolysis, fatty acids and glycerol molecules are moved from fat cells and metabolized to generate energy. As it burns fat, the body creates ketone bodies. When we’re in ketosis, these ketone bodies become what carbs are to you right now, your primary fuel. The brain can use ketones, as can skeletal muscles, the liver—the list goes on. In fact, the heart prefers ketones to glucose. That’s not to say that the body doesn’t need glucose at all. Red blood cells, for instance, require glucose, and so does the brain (although a certain amount of its energy requirements can be met by ketones). But the body can actually create glucose on its own through a process called gluconeogenesis.
In gluconeogenesis, the liver turns amino acids—the building blocks of protein—and fatty acids into glucose. There’s no need to eat carbohydrates to get glucose! It can be challenging to make the switch from preferring glucose as the primary fuel to preferring fat because the body isn’t entirely accustomed to using fat. It has to ramp up the processes needed to metabolize fat until it finally is able to prefer fat to glucose as a fuel source—a process that’s known as “fat adaptation” or “becoming fat-adapted.” Once you’re in nutritional ketosis and burning fat as your primary fuel, blood sugar and insulin levels drop and levels of HDL (good) cholesterol increase.
Your body starts to burn its stored fat along with dietary fat, which means that you start to lose weight—and, even better for your health, the visceral fat around your vital organs, which is linked to increased risk of heart disease and type 2 diabetes, shrinks. And remember how insulin alerts the brain if fuel is running low, resulting in hunger? Because insulin is stable on a ketogenic diet and the fuel we need (fat) is right on our bodies, appetite is reduced naturally.
In addition, studies show that nutritional ketosis can be therapeutic for many of today’s widespread chronic health problems, such type 2 diabetes, irritable bowel syndrome (IBS), polycystic ovary syndrome (PCOS), Alzheimer’s disease, and dementia. On a day-to-day basis, people in ketosis often report the following changes in their health:
- Effortless weight loss
- Reduced appetite
- Improved mood
- Ability to eat more without gaining weight
- Lower and more stable blood sugar
- Fewer cravings
- Lower blood pressure
- Clearer thoughts
- Improved sleep
- Reduction in gas and bloating