Am I In Ketosis? Top 4 Ketosis Signs 

Am I in ketosis right now?

If you’re on a keto diet, you’ve probably asked yourself this question many times. After all, your phone doesn’t buzz when you enter fat-burning mode. 

Luckily, your body has other ways of alerting you. Changes in weight, energy, appetite, and mental acuity are all positive signs you’re in ketosis. 

There can be less pleasant signs too. In particular, the commonly-reported collection of ketosis symptoms known as keto flu that can happen in the first 3-7 days of starting keto.  

And of course, you can also measure your ketone levels.

In this article, we’ll cover the top signs of ketosis, along with some tips to make keto easier. Keep reading. 

Positive Ketosis Signs

Look out for these changes as you adapt to a low-carb diet. They mean, most likely, that you’re headed in the right direction. 

#1: Weight loss

One of the first signs of ketosis is rapid weight loss. Most of this weight, however, is water weight. 

That’s right. When you stop eating carbs, your body taps into its carb storage system called glycogen. These stored carbs are mostly water weight, and going keto releases this water—WHOOSH.  

So rapid water weight loss is an early marker of ketosis. The next signpost is sustainable fat loss. 

Fat loss may take more time, often several weeks. Your cells need time to fat-adapt. It doesn’t happen overnight. 

But if you’re several weeks into the ketogenic diet, and the number on scale is slowly creeping downwards, it’s a positive sign you’re in ketosis. 

#2: Mental sharpness

women working from home

Mental acuity is a well-reported keto benefit. In fact, many people say their brain functions best while in ketosis. 

But it’s not just anecdotal. In a study published in the journal Psychopharmacology, higher levels of ketones were linked to better mental performance (including memory improvements) in older adults. 

Think of ketones like eco-friendly super-fuel for your brain. They burn "cleaner", and produce more energy than molecules of glucose.

Normally your brain runs nearly 100% on glucose. But in ketosis, that ratio shifts to favor ketones. 

So if you’re feeling unusually clear headed, there’s a good chance you’re in ketosis. 

#3: Steady energy 

Your energy is tied to your blood sugar. As your blood sugar rises and falls, so do your energy levels. 

It’s like being on a roller coaster. Eating a high-carb meal takes you to the top of the ride, and you feel great. Picture a kid after eating about 10 pieces of Halloween candy. 

But what goes up must come down. And when your blood sugar inevitably crashes, your energy crashes too. 

By switching to fat as your primary fuel, following a keto lifestyle gets you off of this roller coaster ride. Your blood sugar stays more stable, and you can hum through the day with a smooth and steady energy.

#4: Less hunger

People tend to eat fewer calories on a keto diet for a few reasons. It’s a big reason why keto works for weight loss. 

So are keto dieters intentionally cutting calories?

Usually, no. The calorie dips are a natural result of hunger management. Remember the blood sugar rollercoaster? Well, it affects appetite too. When blood sugar dips, you get hungry. (Sometimes even hangry!). 

Keto can help. Along with stabilizing blood sugar, the keto diet has been shown to reduce hunger hormones like ghrelin and neuropeptide Y. 

So if you’re cruising from lunch to dinner without needing a snack, you’re probably in ketosis.  

Ketosis Symptoms

glass of water

Some percentage of people experience headaches, muscle cramps, fatigue, insomnia, or digestive issues in the first week of keto. This constellation of symptoms is called the keto flu.

The keto flu isn’t an actual illness. It’s a label for a rough transition to low-carb living. 

What causes keto flu symptoms? In many cases, it’s your cells needing more time to keto-adapt. 

Researchers believe the brain takes about three days to switch from glucose to ketones as fuel. During the transition, the brain is low on fuel. 

Electrolyte deficiency is another potential cause of the keto flu. When you eat a low-carb diet, you lose more sodium and potassium through urine. If these electrolytes aren’t replaced, deficiency symptoms can develop. 

Low sodium and low potassium symptoms are eerily similar to keto flu symptoms. The truth is, the keto flu is very often the low-electrolyte flu

Dealing with the keto flu means getting your electrolytes handled, giving your body time to fat adapt, and—if gut issues exist—eating more fiber from non-starchy vegetables.  

Okay, one more ketosis symptom: keto breath!

Yes, some folks report fruity-smelling breath while following a keto diet. This is probably due to elevated levels of acetone (a type of ketone) in the mouth, and can be rectified with mints or chewing gum. 

Measuring Ketones

man taking his ketone levels

Beyond subjective signs, you can also measure ketones in the blood, breath, and urine. Of the three, blood testing is the most reliable and validated method to confirm you’re in ketosis. 

At-home devices make this easy. Just prick your finger, insert the test strip, and out pops the result. You’re looking for ketone levels between 0.5 and 3.0 millimolar beta-hydroxybutyrate (BH)—generally considered the optimal range for nutritional ketosis. 

Are higher ketones always better? Not necessarily. 

In the book Keto Answers, Dr. Anthony Gustin and Chris Irvin discuss how ketone levels may fall over time as someone keto-adapts. In other words, lower ketones may indicate a more functional state of ketosis. 

Here’s the bottom line. While ketone measurements can be a useful barometer of success, don’t become obsessed with ketone levels. Rely more on ketosis signs from your body and mind. 

They’re why you went keto in the first place, right?

How To Know You’re In Ketosis

To know you’re in a ketogenic state, look out for the signs. 

If you’re losing weight and feeling sharp, steady, and in control of your hunger—these are all positive ketosis signs. And if keto flu symptoms like headaches, cramps, constipation and low energy should arise (and persist), look to fiber and electrolytes as solutions. 

For keto-friendly recipes with plenty of both, stop by the Keto and Co blog! See you there, and thanks for reading.  

Author: Brian Stanton

Bio: Brian Stanton is the author of Keto Intermittent Fasting, a certified health coach, and an expert in the keto diet, fasting, and gut health. Follow Brian’s work by visiting his website at

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