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The Ultimate Guide To Ketosis and the Keto Diet

Louise | August 13
The Ultimate Guide to Ketosis and the Keto Diet #keto #article

Unless you live under a rock, you’ve heard of the Keto diet by now. But exactly what is Keto and how does it affects your body?

If you are the kind of person that asks the tough questions about a new diet, then you are in the right place. This article is a deep dive into the science of the Keto diet.

By the time you are finished with this article, you will have a solid understanding of how this all works. Let’s jump right in and cover the basics.

What is Ketosis?

To understand a ketogenic diet, you need to know all about ketone production. This is the process that powers weight loss when using a Keto diet.

Keto gets its name from small molecules in your body called ketones. When your body’s reserves of stored carbohydrate run low, body fat and ketones become the go-to fuel sources for the various cells in your body.

This is a good place for a ketosis definition.  When someone says they are “in ketosis” this means that they have tuned their diet to provide fat and ketones as fuel for their body, rather than glucose. Doing this is associated with a wide array of health benefits from increased satiety and reduced cravings to enhanced mental alertness and stable blood sugar levels.

Still not sure what ketosis is? Check out this explanation from Dr. Berg:

Let’s take a look now at how ketones are formed in your body.

What are Ketones?

Ketones, or ketone bodies, are formed when your body breaks down fat for fuel.

When glucose levels are low, your body turns to stored fat for energy instead. This fat is broken down in your liver and ketones are produced in the process. (1) This process is called ketogenesis.

These ketones serve as a clean fuel for certain cells in your body, including brain cells.

3 types of ketones are created during ketogenesis:

  1. Acetoacetate (AcAc)
  2. Beta-hydroxybutyrate (BHB)
  3. Acetone

The Ultimate Guide To Ketosis and the Keto Diet

Acetoacetate is created first when fatty acids are broken down in the liver. Beta-hydroxybutyrate and acetone are both created from AcAc. Although BHB is technically a carboxylic acid, it’s commonly considered a ketone.

And at the point, your ketone blood level reaches 0.5 mmol/L you’ll be in a state called “ketosis.” When this state is the result of following a specific diet plan it’s called “nutritional ketosis”. Learn more here.

How To Achieve A Ketogenic State Using A Low Carb Diet

The most important factor, by far, for getting into a ketogenic state is to restrict your intake of carbohydrate. We’ll get into this in greater detail.

Keto for Weight Loss

Being in a ketogenic state involves several mechanisms that benefit those trying to lose weight. Your appetite is lowered and your energy levels are high – a great combination!

Also by reducing carbohydrate intake, your body naturally produces less insulin, a hormone made by the pancreas which helps regulate blood sugar. Insulin is also essential for the storage and retention of body fat. With lowered insulin, the stored fat in your body becomes more accessible as an energy source.

If you calculate your macros precisely and eat to achieve and maintain ketosis, there’s no reason you shouldn’t experience weight loss. There are lots of great reasons for following a Keto diet, though – far more than just weight loss. We’ll get to that in a bit.

So how do you know if you are producing ketones or not? Let’s take a look at some easy ways you can know for sure.

Signs You’re In Ketosis

So you have carefully followed instructions and monitored your food intake. You think your body is making ketones – or at least you hope so – but how can you be sure?

The good news is that your body gives off some signs naturally that can tell you if you are in a state of ketosis. These include:

  • Weight loss. This can be dramatic during the first week as the body’s stored sugar (glycogen) is used up. Each molecule of glycogen in the body holds 3-4 grams of water. When the glycogen is used up that water is flushed from your system.
  • Reduced appetite. When you’re producing ketones, ghrelin – a hormone that stimulates appetite – is suppressed, resulting in a reduced interest in snacking. (2)
  • Dry mouth and increased thirst. Switching to a low-carb diet means your body will be getting rid of lots of water, leaving you thirsty. A dry mouth might be annoying but it’s a surefire sign that you’re on the right track.
  • Keto breath. Ketones have a distinct sweet or fruity smell due to the release of acetone in the breath. For most people, this goes away within a few weeks.
  • Symptoms of “Keto flu”. If you’ve just started out with Keto and you’re feeling sluggish, this is actually a sign that things are progressing well. Your body can take up to a month to adjust to using fats instead of carbs for fuel. The symptoms differ from person to person but often include headaches, fatigue, and difficulty focusing. Some people also experience insomnia or digestive issues. (Keep reading to find out what to do about this!)

The Ultimate Guide To Ketosis and the Keto Diet

All of these are signs of ketosis, but you might want more solid proof. So how can you measure your ketone levels? In the next section, I will show you how.

How to Test For Ketones

Not too long ago it would have been close to impossible to accurately test for ketone levels at home. However, with the increasing popularity of the Keto diet, a number of accurate methods for home testing have emerged.

Each of these options has its pros and cons, which will be outlined for you below.

1. Blood Testing

You can detect beta-hydroxybutyrate (BHB) in your blood. To do this at home you need a ketone meter. This looks very much like a blood glucose meter a diabetic uses to track their sugar levels.

All you do is place a ketone testing strip into the meter, and then use the lancet that comes with the meter to make a small pinprick on your finger. Place the drop of blood on the strip and check the reading.

Testing your blood for ketone levels is the most effective and accurate way of knowing how far you are into ketosis. Because of the built-in precision, this is the best strategy if you’re shooting for optimal ketone levels.

However, some people may not want to prick their finger on a regular basis. Also, the cost can be a bit much: expect to pay $25-$70 for the meter, and $1-$2 per test strip.

2. Urine Testing

The ketone found in your urine is acetoacetate (AcAc). The ketones your body cannot use are excreted through your urine in the form of AcAc.

Having a high level of acetoacetate is not very closely related to your level of blood ketones but can serve as a reasonable indicator, especially when you’re new to Keto.

All you will need to test ketones in your urine is a pack of testing strips. These can be as cheap as $7 for 50 strips, making them much more affordable than blood testing equipment.

The process is simple: dip a testing strip in a urine sample or hold it in the flow of urine and wait about 15 seconds to see the color change. Doing so, you can find out generally how many ketones are present by comparing the color on the strip to the examples on the package.

Dr. Andreas Eenfeldt, M.D. points out that there are some drawbacks to this testing method. “Results can vary depending on how much fluid you drink. The strips don’t show a precise ketone level. Finally, and most importantly, as you become increasingly keto-adapted and your body reabsorbs ketones from the urine, urine strips may become unreliable, even if you’re in a ketogenic state. Thus, the test may sometimes stop working – always showing a negative result – when you’ve been in ketosis for several weeks.”

The Ultimate Guide To Ketosis and the Keto Diet

3. Breath Testing

When testing your breath for ketosis, you are looking for acetone, which is formed from the breakdown of fats and other ketones.

There are ketone breath testing units available right now for between $170 and $240. Although this is a non-invasive and reusable option, there is that high initial outlay.

These units attach to your smart device or computer for easy data tracking. By blowing into the testing unit, you will be given an almost instant reading of acetone levels in your breath.

This method will give you a good indication of whether you’re producing ketones. Breath testing tends to be more accurate than using urine strips, but less precise than blood testing. It’s a great option for someone who loves technology and gadgets.

Benefits of Ketosis

The benefits of a low carb diet extend far beyond weight loss.

With a significant body of research already available and more on the way, Keto is beneficial to your overall health in a number of ways…

  • Reduced appetite. The healthy fats and protein you consume on Keto keep you feeling fuller for longer. This, along with reduced levels of the “hunger hormone” ghrelin, can help you to lose weight. (3)
  • Lowered levels of triglycerides. Triglycerides are fat molecules linked to heart disease. Studies show that a Keto diet can reduce them dramatically. (4,5)
  • Lowered blood pressure. Hypertension increases the risk of stroke, heart disease and renal failure. Keto can help reduce high blood pressure to healthier levels. (6)
  • Improved HDL cholesterol levels. Low-carb diets can increase levels of HDL cholesterol (HDL), often called the “good cholesterol”. (7)
  • Reduced blood sugar. A ketogenic diet can help type-2 diabetics manage their condition, and may help prevent diabetes in people at high risk. Using a low carbohydrate diet, some diabetics have even managed to stop taking medications. (8)
  • Improving symptoms of metabolic syndrome. The collection of symptoms known as metabolic syndrome includes high blood pressure, high blood sugar, central obesity, and high triglycerides. Following the Keto diet can effectively treat each of these. (9)

The Ultimate Guide To Ketosis and the Keto Diet

Side Effects of Ketosis

Despite having many positive effects, there are some negative side effects of being in a ketogenic state that you should be aware of. For most people, these do not represent a significant problem and can be managed.

Electrolyte Deficiencies

On a Keto diet, your body excretes more electrolytes than usual, including salt and potassium. This can lead to deficiencies, potentially causing symptoms such as constipation, lethargy, fatigue and even an irregular heartbeat. (10)

To ensure you don’t encounter any problems, you should actively increase your intake of these nutrients when on a Keto diet. This may mean adding more salt to your food and eating more potassium-rich foods, like avocados and spinach.

Keto Flu Symptoms

Many newcomers to Keto experience a range of minor ailments referred to as “Keto Flu”, as some of the unpleasant features are similar to a regular flu. Symptoms include fatigue, irritability, upset stomach, nausea and sugar cravings.

The key cause of keto flu is your body adjusting to its new diet and to using ketones for fuel. For most people it does not last more than one week.

You can lower the impact of keto flu by maintaining a high electrolyte intake and increasing fat and calories to ensure your body has enough energy.

Ketosis vs Ketoacidosis

Ketosis is not to be confused with ketoacidosis which is very different. For the vast majority of people, there is no need to ever worry about ketoacidosis.

According to Erika Brutsaert, M.D., Assistant Professor at the Albert Einstein College of Medicine, “Diabetic ketoacidosis (DKA) is most common among patients with type 1 diabetes mellitus and develops when insulin levels are insufficient to meet the body’s basic metabolic requirements.”

Ketosis is a natural state that is regulated by your body. (11) Ketoacidosis occurs when your body cannot produce enough insulin and both ketones and blood sugar rise very high. (12) As noted by Dr. Brutsaert, this is primarily an issue for those suffering from type-1 diabetes, or very rarely with type-2 diabetes.

Without enough insulin, ketones can increase to dangerous levels, resulting in a condition called ketoacidosis. This is a medical emergency and can even be life-threatening if not remedied.

If you are diabetic it’s a good idea to check with your doctor before starting a ketogenic diet, to ensure it’s a good fit for you.

The Ultimate Guide To Ketosis and the Keto Diet

Using a Ketogenic Diet to Become a Ketone-Making Machine

Now, the part you have been waiting for. We will now look at how you can achieve this state using a ketogenic diet.

The basics of this diet are easy to get your head around, however, you will need to fine tune the intake of each type of food to find the right balance for you. This is why testing ketones are so important in the beginning, so you can see how your body is reacting to this diet change.

Keto Macros

There are 3 dietary macronutrients, commonly abbreviated to macros:

  • Proteins
  • Carbohydrates
  • Fats

Keto works on the basis of maintaining set ratios of nutritional macros. Once you’ve got that down you can focus your attention on micronutrients – the vitamins and minerals provided by leafy and fibrous vegetables.

Now we will take a look at some of the standard macros and ratios for a Keto diet.


The central feature of a Keto diet is lowering your intake of net carbs to no more than 25g a day. This will ensure you get into a ketogenic state and stay there.

Because carbohydrates are converted into glucose by your body, going overboard on the carbs can do more than blow your macros, it can halt ketone production completely.

Removing carbohydrates more difficult than you think. They are hidden in a lot of foods you wouldn’t expect so keep your eyes peeled to avoid “carb creep”.

Nutrition and Health Coach Christina Oman says, “I tell my clients to think of their daily carb allowance as a budget.”

She goes on to say, “Use your allowance wisely … you can fill up on nutrient dense food such as broccoli, cauliflower, aubergine and leafy  greens. Spinach has 1.6g of carbs per 100g portion. You would have to eat 1.25kg of spinach to get to your maximum carb level. I challenge anyone to try to eat that much spinach!!”


On a ketogenic diet, you should eat roughly 1g of protein per pound of lean muscle. Check out our article on calculating macros if you need help with this calculation.

Or you could skip calculating altogether and use our One Question Macro Calculator.

Protein should make up approximately 30% of your caloric intake. Although you may be tempted to squeeze in more protein, there is a very good reason to keep it at this level.

When you eat excess protein a process called gluconeogenesis occurs. This process converts protein to glucose and can potentially kick you out of ketosis.

Registered Dietician Kristen Mancinelli, MS, RD says, “It’s important to note that the ketogenic diet is NOT a high-protein diet and does NOT promote excess meat consumption. Eating too much protein will PREVENT the metabolic changes that result in ketosis (the state in which the body uses primarily fats, rather than glucose, for energy).”

The Ultimate Guide To Ketosis and the Keto Diet


Fats make up the largest portion of a Keto diet – up to 65%.

After limiting carbohydrates and eating a moderate amount of protein, the rest of your diet should be made up of healthy fats like coconut oil, olive oil, and ghee.

Nervous about eating fat after hearing for years that it’s bad for you? “Don’t be afraid to eat natural fats. Contrary to what we’ve all been told, saturated fat is not the enemy,” says Abby Roaquin, BSN, RN, a Registered Nurse who lost 63 pounds and reversed her prediabetes on Keto. “The real culprit? Added sugars, refined and processed carbohydrates.”

Fats have 9 calories per gram, compared to the 4 calories per gram you’ll find in proteins or carbs. Fats are energy dense, satiating, and they make everything taste great. If you’re hungry, eat more fat.

Types of Keto Diets

There are different types of keto diet out there that you can experiment with. Just some of the Keto variants include:

  • The Standard Keto Diet (SKD). Suitable for the vast majority of people, the Standard Keto Diet uses the standard Keto ratios of fat, carbs and protein.
  • Targeted Keto Diet (TKD). This is great for athletes and active people. It allows for slightly more carbohydrates right before intense workouts.
  • Cyclical Keto Diet (CKD). This is great for weightlifters and follows a regular Keto diet, punctuated by carb loading days where carb intake is significantly increased.
  • High Protein Ketogenic (HPK). This type of Keto diet increases protein, but not by enough to cause gluconeogenesis. Note that when using HPK, it can be hard to find the right balance.

Should You Use Exogenous Ketones To Get Into Ketosis?

Exogenous ketones are ketone supplements that are taken to boost ketone levels in your body.

Used the right way, they can push you into ketosis quite quickly and they may help suppress your appetite. But for all the benefits of Keto, you’ll still want to reduce carbohydrate intake and eat nutritious foods.

When used, exogenous ketones can get you into ketosis faster, and also give you more energy for high-intensity exercise. They may also help some people reduce their keto flu symptoms by boosting mental clarity.

Should You Use Fasting To Get Into Ketosis?

Intermittent fasting does not mean starving yourself – it simply limits the times of the day, or days of the week, when you eat food.

The Ultimate Guide To Ketosis and the Keto Diet

Fasting in conjunction with a low carb meal plan can fast-track your path to ketone production. Especially when starting out, it can speed up the process of weaning your body off of its dependence on glucose.

Fasting has also been associated with health benefits, including lower blood pressure and cholesterol. (13) You don’t need to fast for effective Keto, but it is worth a try if you are finding it hard to enter ketosis as you get started.

Try a Ketogenic Diet for Health and Wellness

The benefits of following a keto diet are well backed by scientific evidence. Keto can help you lose fat and lead a healthier life. While it can be difficult to change a lifetime of eating habits, the short-term struggle is definitely worth it in the long run.

So what are you waiting for? Calculate your macros and get started today.

If you’re wondering how MTFHR fits in with a ketogenic diet, listen to our exclusive interview with Carrie Brown on this subject.

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Louise co-founded Louise's Foods, Paleo Living Magazine, Nourishing Brands, & CoBionic. She has considerable research experience but enjoys creating products and articles that help move people just a little bit closer toward a healthy life they love.