Ketosis: What it is, Symptoms, Benefits, Side Effects & More


What is Ketosis? If you’ve spent any amount of time investigating low-carb diets, there’s no doubt that it’s a term you’ve heard almost everywhere you go, but what does it mean?

More importantly, why is Ketosis important for losing weight the low-carb way? How do you create it? And what possible drawbacks could there be?

Ketosis in a Nutshell

In a nutshell, Ketosis is a metabolic process that occurs naturally in the body when it can’t generate energy from its usual source, carbohydrates. 

As the body shifts to using fat for fuel, chemicals called Ketones are created in the liver and pushed into the bloodstream to provide the energy needed to get us through the day.

This transition from one energy source to another can have several positive benefits for our health and well-being, but it also has potential drawbacks. 

In this comprehensive guide, we’ll outline everything you need to know about Ketosis, including its causes, why it’s helpful for those on a weight loss mission, and more.

What is Ketosis, and How Does it Work?

Ketosis is why low-carbohydrate diets like the Ketogenic diet work, forcing the body to stop relying on glucose (a sugar created from the carbs we eat) and instead burn up the fat stored in our bodies. 

To understand this better, we can look at the role of insulin, a hormone produced in the pancreas that plays a vital role in managing our natural glucose levels. 

Whenever we devour carbs, the sugars and starches become glucose, and the pancreas pumps enough insulin to carry it from our bloodstream into energy-giving cells.

When we cut out (or even cut down) our carbohydrate intake, our insulin levels are lowered, so getting enough glucose to meet our energy needs is impossible.

When this happens, the body has to switch to an alternate fuel source. It does this via the liver, which breaks down fat and converts it into Ketones, which, as we’ve already seen, enter the bloodstream to serve as our new energy source. 

Since most of the extra pounds we carry are from unused fat stored in the body, burning it through Ketosis helps us shed those pounds and get closer to our ideal weight.

How to Achieve and Maintain Ketosis


Now that you know a little about how Ketosis works, you should be getting some idea about how to achieve it. 

It all comes down to reducing the number of carbohydrates you eat and replacing them with healthy fats.

Doing this may mean a radical overhaul of your diet, avoiding high-carb foods like pasta, bread, and even certain types of fruits and vegetables and choosing high-fat options like fish, fresh meat, nuts, seeds, and low-carb vegetables. 

See our guide to the best foods to eat on a Ketogenic diet for more examples of what you can safely put on your plate.

How to Transition to a Ketogenic Diet Safely

How you transition to a Ketogenic diet is up to you. 

Some people like to go all-in from day one, ensuring that their daily food intake contains a maximum of 10% carbs, 20% protein, and 70% fat.

While this is a great way to hit the ground running and lose weight faster, the immediate change in fuel source can bring about adverse side effects like the Keto-Flu, more of which later. 

To minimize the chances of experiencing these side effects, other people prefer to transition more gradually, lowering their carb intake and increasing their fat consumption slowly over a few weeks until they hit that 10:20:30 sweet spot.

How to Maintain Ketosis 

The time it takes to get into Ketosis varies from person to person. It depends on several factors, such as your metabolic rate, lifestyle, and how rigidly you’re sticking to the ketogenic diet.

Once you get there, there are certain things you can do to maintain Ketosis for as long as you need to achieve your weight loss goals. 

The first is to stay on top of your macronutrients. 

Use a Keto calculator to determine how many grams of carbs, protein, and healthy fats you should eat each day, then plan your daily meals to ensure you’re getting those amounts without going over. 

As with all health goals, you’ll have a great chance of success by exercising regularly.

Not only does this burn off any excess glucose and encourage further fat burning (helping you stay in Ketosis), but it can also be a great way to relieve stress and improve sleep quality. Both of which are factors that can influence your body’s ability to get and stay in Ketosis. 

How Will I Know If I’m in Ketosis?

The most obvious signs that you’re in Ketosis are that your weight begins to drop and your appetite decreases, among the positive side effects of changing your macronutrient intake. 

Suppose you’re not yet noticing any significant changes. In that case, there are commercially available blood and urine tests that measure the levels of Ketone in the body and tell you whether or not you’re in a state of Ketosis.

What are the Main Symptoms and Side Effects of Ketosis?

While most people can achieve and maintain Ketosis safely, it can bring about a few unpleasant side effects, especially in the early days as your body adapts.

These Include:

Keto Flu

The Keto Flu is precisely what it sounds like Flu-like symptoms such as headaches, chills, and fatigue. These symptoms usually occur in the first week of transitioning to a Ketogenic diet. 

Although Keto Flu is not a medically-recognized condition, those switching to a low-carb diet report it also includes other symptoms such as sugar cravings, nausea, and trouble sleeping.

Fortunately, this is a short-term problem. 

Once your body gets used to being in a state of Ketosis, the symptoms should clear up on their own, and as the pounds drop and your energy rises, you may feel better than ever. 

Keto Breath

You may be lucky and avoid the Keto-Flu, but you’ll be even luckier if you can escape Keto Breath. 

One of the most common side-effects of Ketosis is that this change in your breath is caused by acetone, a particular type of Ketone produced in the liver and leaves the body via your breath. 


Carbohydrates such as whole grains and high-carb fruits and vegetables contain plenty of fiber, essential for protecting the gut and keeping us regular

When we decrease our carb intake, we also reduce the amount of fiber our bodies need. As a result, it’s not uncommon to experience a bout of constipation early in your Ketogenic journey.

To avoid this most uncomfortable Ketosis side-effect, stay hydrated and eat more low and zero-carb vegetables. 

Other Common Symptoms 

As your body adjusts to Ketosis, you may urinate more frequently and feel dehydrated. 

The switch in energy sources can also leave you feeling a little tired within the first few days, but don’t worry; you’ll soon be experiencing a lot more energy once your body gets used to your new lifestyle. 

What are the Potential Health Risks of Ketosis?

Most common Keto side effects disappear after doing nothing more serious than making you feel a little crummy for a few days.

However, there are some bigger potential problems that it’s worth being aware of before you decide if a low-carb diet is proper for you. 

Liver and Kidney Problems 

If you’re relatively healthy and don’t have any pre-existing liver or kidney problems, you should have nothing to worry about in this area. 

However, it is important to note that individuals with existing conditions in their liver or kidneys may be advised not to pursue a Ketogenic diet. 

For example, if you have any liver damage, your liver may be unable to properly deal with excess Ketones, which could cause even more problems in this vital organ.

Likewise, the changes to your protein intake could place additional stress on the kidneys, which play a crucial role in taking waste products from the blood and eliminating them from the body. Although healthy kidneys should be able to handle this, the process could further exacerbate problems with kidneys that are already compromised. 


While a low-carbohydrate diet aims to produce Ketones, it is possible to overdo it.

When the Ketone levels in your bloodstream get too high, this causes Ketoacidosis, which could be life-threatening if left untreated.

Ketoacidosis is most common in people with unmanaged diabetes. So, if you’re diabetic yourself, it’s important to discuss your Keto diet plans with a healthcare provider before you start to ensure it’s safe. If they give you the OK, keep in regular contact with them to monitor your blood sugar and Ketone levels, and stop your diet immediately if there are any signs of danger. 

What are the Health Benefits of Ketosis?

Though Ketosis presents some possible short-term side effects, these are typically outweighed by the potential long-term benefits.

Though most people switch to a ketogenic diet to lose weight by reducing their appetite and burning more fat, there are other possible upsides, including: 

Improved Blood Sugar Levels and Insulin Sensitivity

Reducing carbohydrate intake means your body no longer relies on glucose as its primary energy source. This reduces the amount of glucose that enters your bloodstream, a process that can positively impact your blood sugar levels. 

Since insulin is no longer used to carry as much glucose into the blood, Ketosis can also help improve your insulin sensitivity. 

For this reason, some people with type 2 diabetes or prediabetes consider a ketogenic diet to help them better manage their condition. As we mentioned earlier, people with diabetes should always talk to a doctor before determining if Ketosis is safe and sustainable for them. 

Improved Cognitive Function

Few people are aware that the Ketogenic diet was initially developed as a treatment for epilepsy.

Given its effectiveness for this condition, medical experts have explored its potential as a treatment for other neurological disorders such as Parkinson’s and Alzheimer’s.

Even if you don’t live with either condition, anecdotal evidence suggests that being in Ketosis can help to lift brain fog, increase mental clarity, and improve focus. 

Everything You Need to Know About Ketosis: A Final Summary

We wrote this guide to empower you with all the information you might need about Ketosis. 

If you’ve been paying attention, you’ll have learned that Ketosis is a process through which the body burns fat, producing Ketones released into the blood to give us energy. 

You’ll also have learned the potential benefits, such as weight loss, increased energy, and improved blood sugar levels, as well as symptoms like Keto Flu and the possible health risk, all of which should be enough to help you determine if a ketogenic diet is a safe and suitable way to achieve your health goals.

If you’re still undecided, talking to a medical professional can help, as will our comprehensive beginner’s guide to the Keto diet.