5 Signs and Symptoms To Tell If You're Fat Adapted on Ketogenic Diet
Signs You Are Fat Adapted

5 Signs of Fat Adaptation on The Keto Diet

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“Fat-adaptation” is a somewhat vague term describing the profound changes that happen after switching from a standard diet to a ketogenic one.

In order to experience these changes, you need to commit to consuming a very limited amount of carbohydrates (20-25 g per day or less) and to stick to that limit at least for a couple of weeks, while at the same time eating sufficient fat and protein.

Once you commit to this way of eating you’ll notice some subtle, yet amazing transformations that your body will go through, in addition to the stable weight loss.

How Long Does It Take To Become Fat Adapted?

Even though the keto adaptation timeline varies from person to person, the fat adaptation process can take anywhere between 4-6 weeks or more.

If you’ve just started keto and want to experience this stage, you need to follow a strict ketogenic diet meal plan and stay in ketosis all the time without cheating.

If you are just starting out on this diet and this is your first week, you might also want to check these signs that you are in ketosis.

How to Tell If You Are Fat Adapted

In this article, we’ll shed some light on the different signs that you will notice once you start getting fat-adapted, and explain each one of them in detail.

#1. Improved Energy

In the initial phase of the ketogenic diet (also sometimes referred to as induction phase), your body will be learning how to use fat for fuel instead of glucose.

While at first, this might make you feel tired and lethargic. This will only last until your body adapts to the changes in your diet.

Once you switch to a fat-burning metabolism and your body adjusts to it, you’ll experience blood sugar levels that are lower and more balanced, and, as a consequence, your energy levels will remain stable through the day.

As a result, a lot of people report an increased motivation to exercise and be more physically active, which, in turn, is an excellent addition to your weight-loss arsenal.

#2. Better Sleep

Sleep better

While you might struggle with some insomnia at first, this will improve with time and you might find that you sleep much better compared to before starting the keto diet.

Many people experience a deeper, calmer sleep, and waking up feeling more refreshed. An adequate magnesium intake (which is necessary on a keto diet) will also help you sleep better.

Since you have a better sleep every night, you will wake up refreshed and energised every morning.

#3. Practically Non-existent Carb Cravings

In the beginning of the adaptation process, and especially if your sugar consumption was high before starting keto, you might experience some carb cravings. However, you will notice them disappear with time.

Carb cravings, in the beginning, are related to two things. First off, it is a reflection of the metabolic change that your body is undergoing, as carbs are a quick and easy energy source, and secondly, it is related to your past habits.

If your typical comfort foods were pizza, sweets, potatoes, bread and the like, you might miss them at first.

Fear not, the carb cravings will subside and disappear with time. There’s a lot of marvelous recipes out there that will help you enjoy your diet to the fullest, and even make a keto version of many popular dishes.

For inspiration, check out our recipes section!

#4. Increased Physical Endurance

Running woman

Once your body learns how to use fat for fuel, it will be able to access your fat storages much easier than before.

During activities where a high level of endurance is necessary, you will no longer depend on your glycogen stores (which deplete in about 90 minutes of a high-intensity activity), but will, instead, use your own body fat for energy.

You’ll not experience the crash related to glycogen depletion and will be able to maintain a stable performance.

If you’re a long-distance runner, hiker or cyclist, or if you are just interested in improving your endurance, this is definitely something to consider.

#5. Decreased Appetite

As fat and protein provide a higher level of satiety than carbs, you’ll notice that you feel naturally less hungry than before.

You will no longer feel ravenous when not eating for a bit longer than usual, and will be able to manage your hunger much better.

Your weight loss rate will also improve and become more predictable.

Related: The Comprehensive Guide to Using Ketosis for Weight Loss

Should You Still Count Calories?

Calorie counting is still necessary for most people even on the keto diet because in order to lose weight you still need to eat less than what you burn.

However, you will notice that eating less is much easier, even for extended periods of time (a couple of months or more).

The keto diet is not some sort of a magical appetite suppressant, though, and if you are very active, make sure to provide your body with enough energy.

Starving yourself will hardly lead to good results in the long run, and will make it more difficult to stick to your goals.

Another thing to consider is that being fat adapted is not the same thing as being in ketosis. In fact, once you become fat adapted, you might occasionally get out of ketosis on purpose. For example, for specific high-intensity training sessions, carb refeed, or during the holidays. If your break from keto is not too long (meaning 7-14 days), you’ll still remain fat adapted.

You won’t lose your fat adaptation with a few more grams of carbs every now and then. It usually takes a week or two to start to lose its advantages, so if for some reason you’ve decided to give the keto diet a break but still want to come back to it afterwards, do keep that in mind. 

Nevertheless, even after months of not following macros for ketosis, you’ll likely find the adaptation process easier if you do go back to keto. First, because you already know what to expect and how to deal with it, and second, because your body has gone through it once, so it’ll generally be easier to adapt to it a second time. 

Many people, once they achieve their weight loss goals, decide to incorporate a flexible approach to keto, using it for specific goals, and following strict keto macros only occasionally.

For example, to trim some fat from the holidays, or to prepare for an endurance event, or to enjoy its other health benefits, while staying low-carb most of the time. That’s indeed a strategy worth considering, if you enjoy keto but don’t want to be in ketosis 365 days a year (for whatever reason). 

If you do lazy keto, for example (i.e. eating keto-friendly foods without tracking macros daily), you’ll probably be in ketosis most of the time, but will occasionally be kicked out of it. That’s not dramatic in itself, if it corresponds to your goals.

Being in ketosis doesn’t have to be a goal in itself. You’ll still experience the many benefits of being fat adapted, if you are doing lazy keto, or adapt a slightly more liberal stance to carbs (if you’re still staying low-carb and are in ketosis most of the time).

Keep in mind that everybody is different, so you might experience these signs to a varying degree, or not experience all of them (or not all of them at once).

If you give yourself enough time to become fat-adapted, you will be able to reap many of the amazing health benefits of the ketogenic diet, together with losing the weight you have previously struggled with. Incredible, isn’t it?


You can tell if you’re fat adapted by paying attention to your body’s signals. For example, if you’re able to exercise longer, do not feel hungry as often (or as much), and are experiencing better sleep at night, then you could be fat adapted. 

You may also notice that your blood sugar levels are more stable throughout the day. This leads to better concentration and an improved mood. You’ll also feel more energetic throughout the day. 

You may still need to count your calories despite being fat-adapted if your goal is weight loss. Also remember that being fat-adapted is not the same as being in ketosis. 

Up Next: Weight Loss on Keto: How Much, How Fast and What to Expect

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