The Ultimate Guide to Ketosis: What It Is and How to Achieve It

Articles on keto, nutrition, exogenous ketones, exercise, and more.


Delicious keto recipes for breakfast to dessert, and everything in between.

The Ultimate Guide to Ketosis: What It Is and How to Achieve It

Discover the health benefits of ketosis, a metabolic state that burns stored fat for fuel. Learn the science behind it and how to do it safely.
keto diet

For the majority of your life, you were told carbs are your primary source of energy.  However, there is a more efficient source of fuel that is rarely used: fat. When your body metabolizes fat, it produces ketones, which can then be used by your body’s cells for a number of functions.

The purpose of a ketogenic diet is to eat in such a way — high-fat, adequate protein, low-carb) — that it induces your body into ketosis. In the absence of carbs, your body transitions into this fat-burning state, producing ketones.

The scientific community is constantly revealing the inner workings and potential applications of a keto diet. Today, many people turn to keto to enhance their mental performance, body composition, mood, or to prevent a number of chronic diseases.

This guide will offer the information you need about ketosis, the health benefits of the keto diet, and how to test your ketone levels.

What Are Ketones?

Before diving into the ins and outs of ketosis, it’s important to understand ketones. There are three types of ketone bodies:

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

Acetoacetate is the first ketone created from breaking down fat. This then leads to the formation of beta-hydroxybutyrate, the most abundant ketone in the human body.  Finally, acetone is created spontaneously as a side product of acetoacetate via decarboxylation[*].

Why Your Body Uses Ketones

From an evolutionary perspective, humans have always relied on ketones for energy when glucose sources were scarce (i.e. no fruits available during winter). Your ancestors likely had frequent periods of time when high carb-heavy food wasn’t immediately available. For this reason, the human body can still adapt to burning ketones for fuel.

Ketosis is a natural metabolic state — in fact, most babies are born in a state of ketosis[*]. However, with the abundant sources of carbohydrates available today, people enter ketosis and it becomes a dormant metabolic pathway. The purpose of the keto diet is to intentionally remove carbs, therefore forcing the body to turn to an alternative fuel source.

The Benefits of Ketosis

Optimal nutrition is different for everyone — there is no one-size-fits-all solution. That said, a whole-food based ketogenic diet provides a host of benefits for most people, including decreased body fat, improved insulin sensitivity, and boosted mental and physical performance.

Ketosis has also been shown to help prevent or improve certain medical conditions, including epilepsy, Alzheimer’s disease, cancer, heart disease, depression, and migraines[*][*][*].

Weight Loss Benefits of Ketosis

Ketosis can be a desirable approach to weight loss for the following reasons[*]:

  • Increased fat oxidation: In ketosis, your body burns dietary fat and your own body fat as its primary source of fuel.
  • Hormone regulation: Ketosis can help sustain weight loss by regulating hormones that affect weight. That means a keto diet can help you avoid cravings for unhealthy foods, reducing the chance of gaining weight back.
  • Appetite suppression: Feeling full, even on a weight loss diet, means you can better listen to your body’s true hunger signals.
  • Blood sugar regulation: Weight loss diets that include high carbs can create blood sugar spikes that leave you feeling hungry again soon after eating — as well as tired and unfocused. On the keto diet, you may experience balanced insulin levels, which can thereby prevent blood sugar spikes.

Exercise Benefits of Ketosis

Ketosis can be beneficial during exercise by[*]:

  • Increasing and prolonging your endurance levels.
  • Adapting your body to burn more fat, which helps preserve glycogen in the muscles.
  • Improving the function of mitochondria, enzymes, and fat usage to improve overall health and physical performance long-term.
  • Using oxygen more efficiently, leading to better performance for endurance athletes.

Mental Focus Benefits of Ketosis

An unbalanced diet can lead to a lack of mental clarity, showing up as a foggy brain, having a hard time remembering important facts, or struggling to stay focused on tasks.

Ketones improve the efficiency and energy levels of the mitochondria, which produce energy for cells in your body and brain.

Eating healthy fats is essential. Every single cell in your body needs fat to function, especially your brain cells. The brain is the fattiest organ, comprised of over 60% fat and prefers fat for fuel[*].

What Are Exogenous Ketones?

Exogenous ketones are a supplement used for boosting performance and energy, or complementing a low-carb diet designed for weight loss. Exogenous ketones may help you get into ketosis initially or help you get back into ketosis after eating carbohydrates.

Benefits of Exogenous Ketones

Exogenous ketones, like nutritional ketosis, come with a number of health benefits, including[*]:

  • Higher ketone levels: Especially in the morning or between meals, ketones boost your body into an effortless fat burning mode.
  • Physical performance: Taking ketones before and during workouts can give you energy and decrease the need for oxygen.
  • Mental focus: Ketones can improve energy levels for brain cells, increasing mental output and sharpening focus.

How to Start Taking Exogenous Ketones

You can take Perfect Keto’s Exogenous Ketone Base any time of day. To start, take them in the morning or between meals for sustained energy levels, or midday for sharper focus. You can also try taking them before or during exercise for a zero-sugar energy boost (try the Perfect Keto Perform sports drink to help fuel your workouts).

Finally, you can take exogenous ketones to boost your ketone levels after a carb-laden meal.

Notes on Exogenous Ketones for Weight Loss

Exogenous ketones are very effective supplements, but they should be supplementary to a low-carb, ketogenic style of eating. Exogenous ketones don’t cause weight loss, but they help raise your ketone levels. In other words, they don’t directly make you burn fat, but they can help make it much easier to incorporate a lifestyle that leads to fat loss.

The Ketogenic Diet Explained

The keto diet is a low-carb, high-fat diet that aims to put your body in ketosis, which is a fat-burning metabolic state.

On the keto diet, roughly 70-80% of your calories will come from fat, 20-25% of your calories will come from protein, and just 5-10% of your calories will come from carbs.

You can calculate your macronutrient needs using the Perfect Keto macro calculator. However, the below sections should give you a rough estimate of your daily intake.

Carbohydrate Intake on Keto

For most people, a range of 20-50 grams of carbohydrate intake per day is ideal on a low-carbohydrate diet like keto. Ideally, these carbs will come from foods high in dietary fiber, such as leafy green vegetables, non-starchy vegetables, and low-sugar berries.

Protein Intake on Keto

Protein is extremely important on keto. To calculate how much protein you need, estimate 0.8 grams of protein per pound of lean body mass. This will prevent muscle loss.

At one point, it was thought that eating any more than 15% of your daily calories from protein would kick you out of ketosis. This is a process known as gluconeogenesis, where too much protein is converted into sugar, thereby raising your blood glucose levels. However, this is just a myth.

Fat Intake on Keto

The remaining 70-75% of your calories on the keto diet will come from fats. Since fat is the main source of nutrition on a ketogenic diet, it’s important to source high-quality, healthy fats like avocado, coconut oil, MCT oil, and nuts and seeds.

Four versions of the keto diet

How to Test Ketones

Eating “keto” foods doesn’t automatically mean you are in ketosis. Ketosis is a measurable state of metabolism, and it’s important to test your blood ketone levels to know if keto is working for you.

There are three methods for measuring the levels of ketones in your body. The different approaches to ketone testing include:

Urine Testing

When ketone levels in your body increase past a useful point, they get excreted through urine. You can easily measure excess amounts of ketones with a urine strip. Keto test strips offer an easy (and affordable) test you can take at home, but the results are not the most reliable.

Blood Testing

To test your ketone levels via blood, you can prick a finger and squeeze a drop of blood onto a test stick. This measures the levels of a specific ketone body, called beta-hydroxybutyrate, in your blood. This is the most accurate — but also the most expensive — a method for testing your ketone levels.

Blood ketone tests measure the amount of beta-hydroxybutyrate (BHB) in millimolar concentration. A urine or breath ketone test should also make it easy to convert its results to mmol. If your ketone levels are between 0.5 and 3.0 mmol, then your body is in a state of ketosis.

Breath Testing

You can measure the amount of acetone in your breath using a breath meter. This measures the presence of ketones on your breath, which unfortunately is the least reliable method of knowing whether or not you’re in ketosis.

Safety and Potential Side Effects of Ketosis

Ketosis is a perfectly safe and natural metabolic state, but it is often confused with another, and highly dangerous, metabolic state called ketoacidosis.

Ketosis Is Not the Same as Ketoacidosis

Ketosis is the metabolic state when fat is the primary energy source instead of carbohydrates. Ketosis is a perfectly normal state of human metabolism.

Diabetic ketoacidosis (DKA), on the other hand, is a dangerous metabolic state that is most commonly seen in people with type 1 diabetes (and sometimes type 2 diabetes) if they aren’t properly managing their insulin levels and diet. The condition can be deadly if untreated[*].

Other Side Effects of Ketosis

Ketosis can be associated with a few minor short-term side effects, particularly when just starting the keto diet. As your body transitions from burning glucose to burning fat stores for energy, you may experience several “keto flu” symptoms including headaches, lethargy, brain fog, fruity-smelling bad breath, and stomach pain.

Another common side effect of ketosis is dehydration. Here’s why: glycogen and carbs are stored in the body with water. It takes four grams of water to store a gram of glycogen, and as you deplete glycogen, you will lose water through frequent urination. To combat this side effect, be sure to include plenty of electrolytes in your diet.

Ketosis Is a Natural Metabolic State

Ketosis is a metabolic state where your body burns fat — rather than glucose — for fuel. The goal of the keto diet is to enter this fat-burning state.

While there are some potential side effects of ketosis, they are minor and temporary — dehydration, lethargy, and headaches. By following a low-carb keto diet and supplementing with ketones, you can reap many potential health benefits, including chronic disease prevention, balanced blood sugar levels, weight loss, and enhanced cognition.


Get more out of keto

Doctored-developed. Backed by science. Do keto better with our tasty foods & supplements

Get more out of keto

Doctored-developed. Backed by science. Do keto better with our tasty foods & supplements

Join the Internet's largest keto newsletter

We'll send you articles, product guides, and exclusive offers customized to your goals.