If you’ve ever attempted the ketogenic diet, then you’re probably familiar with the #1 goal: reaching ketosis.

In case you aren’t familiar, ketosis is the body’s metabolic state which produces ketones, something your body will use as a source of energy. This is the process where your body will begin its conversion from burning sugar to burning fat.

There are plenty of excellent benefits in reaching ketosis and turning your body into a fat-burning machine, the most popular being to lose weight![1]

Keep in mind, however, that reaching ketosis doesn’t automatically occur when you start on a keto diet, but rather it takes some time.

So how do you know when you’ve made it to ketosis? In this article, we’re going to run through the 10 telltale signs that will help you determine if you’re in ketosis.

10 Signs You’re in Ketosis

1. Dropping pounds

One of the surest signs that you’re achieving ketosis is the quick weight loss you’ll experience within the first few days. When you begin restricting your carb intake, the body’s glycogen stores in the muscles are reduced.

Since glycogen is responsible for the retention of water, its water levels dropping leads to your water levels dropping too. This is also why it’s vital to stay properly hydrated and ensure your body is getting enough electrolytes.

While most of this is water weight, it’s nonetheless an encouraging start to a ketogenic diet. After this initial phase of fast weight loss, you’ll continue using your fat stores and begin to lose body fat.

2. Not as hungry

A decrease in hunger is another sure sign that you are achieving ketosis. When your body begins using fat as its fuel source instead of carbs, you can expect to naturally feel a loss of appetite.[4]

And when you do feel hungry, the feeling will also become different. Instead of feeling ravenous for food if you haven’t eaten in a few hours, you’ll instead simply become gradually aware of the need to eat something.

3. Increased mental clarity and energy

One huge perk to going keto is the boost in energy that most people experience. The reason behind this is that your blood sugar levels are becoming far more stable than they were on a higher carb diet. You won’t be experiencing glucose spikes and crashes nor the fatigue that comes with it.[2],[3]

Instead, you can count on your energy staying consistent throughout the day. You can also expect to feel more focused and have a clearer mind, as the typical carb-induced brain fog is now gone.

4. Insomnia

If you’re having some trouble sleeping, fear not! This just means that your body has more energy than it did previously when it was using carbs for fuel.

While insomnia is never fun, it’s only temporary. It should go away once your body and mind have had some time to adjust and learn how to deal with the extra energy that comes from burning fat.

Some things that can help fight insomnia is to make sure you’re well-hydrated and have plenty of electrolytes. It can also help to limit screen time before bed.

5. Digestive issues

Since you’re making a change to your diet, your GI tract will need time to adapt to the different foods you’re consuming and macronutrients your taking in.

Depending on how drastic of a change your diet has become, this could result in temporary diarrhea or constipation. You can expect this to go away after only a week or two, and eating more fiber-rich foods like green veggies can help.

6. Stinky breath and dry mouth

With ketosis also comes the unpleasant side effect of mouth dryness and acetone breath (AKA keto breath). This is also very temporary and should only last a few days, so don’t be discouraged!

If bad breath has you feeling too self-conscious, try brushing your teeth more often and stock up on breath fresheners!

7. Fatigue or dizziness

When your body transitions from using glucose to fat for fuel, you might find yourself experiencing some unpleasant, flu-like symptoms such as fatigue or dizziness. This is known as the keto flu.

While your body’s adaptation can take a couple of weeks, the keto flu will typically resolve much faster than that.

Remember that your body will be flushing out much more water than normal. It’s essential to stay hydrated and get the electrolytes you need to ward off keto flu symptoms.

8. More ketones in your blood

Another big indicator of reaching ketosis is the production of ketone bodies in your blood. Normally, being in ketosis means having between 0.5 to 3 mmol/L of ketones, but this number can vary depending on the source.

Measuring the number of ketones in your blood is more accurate than measuring the ketones in your breath or urine, but it can also be more expensive.[5] Nevertheless, testing the ketones in your blood is the most reliable method.

9. More frequent urination

Cutting out carbs leads to a natural diuretic effect. Your body’s insulin levels are dropping, which will have you making more frequent trips to the bathroom.

This can last for a few days as your body starts producing more and more ketones, and is another sure sign that you’re in ketosis.

10. A decrease in performance

If you’re an athlete or enjoy working out on occasion, don’t be surprised if you find your performance suffering when first starting out on the keto diet.

A decrease in athletic performance is completely normal on ketosis and can last a week or two, or until your body fully adjusts.


While there are more than a few unpleasant symptoms of ketosis, just remember that anything worth doing can be hard!

But feel at ease and rest assured knowing that the negatives are all temporary and are well-worth enduring for all of the positives you’ll reap on the keto diet.

If you’re experiencing one or all of these telltale signs of ketosis, then keep pushing forward, knowing that you’re doing it right.


[1] Veech, Richard L. “The therapeutic implications of ketone bodies: the effects of ketone bodies in pathological conditions: ketosis, ketogenic diet, redox states, insulin resistance, and mitochondrial metabolism.” Prostaglandins, leukotrienes and essential fatty acids 70.3 (2004): 309-319.

[2] Boden, Guenther, et al. “Effect of a low-carbohydrate diet on appetite, blood glucose levels, and insulin resistance in obese patients with type 2 diabetes.” Annals of internal medicine142.6 (2005): 403-411.

[3] Bueno NB, de Melo IS, de Oliveira SL, da Rocha Ataide T. Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomized controlled trials. Br J Nutr. 2013 Oct;110(7):1178-87.

[4] Paoli A, Bosco G, Camporesi EM, Mangar D. Ketosis, ketogenic diet, and food intake control: a complex relationship. Front Psychol. 2015 Feb 2;6:27.

[5] Musa-Veloso K, Likhodii SS, Cunnane SC. Breath acetone is a reliable indicator of ketosis in adults consuming ketogenic meals. Am J Clin Nutr. 2002 Jul;76(1):65-70.