Metabolic ketosis can occur during fasting, pregnancy, infancy, or starvation, but experiencing ketosis and achieving fat-adaptation is not precisely the same.

Granted, eating a diet consisting of no more than 50 total carbs and 20 net grams (total carbs - fiber) of carbohydrates a day is an excellent approach to coaxing the body to rely on fat and ketones rather than glucose (sugar) fuel. However, entering a state of metabolic ketosis, but not necessarily effectively relying on fat as the body's preferred and primary energy source is the essential factor between the two states of being.

Of course, eliminating carbs and sugars can put the body in a ketotic state. Still, fat-adaptation refers to the body converting to systematically relying on and preferring ketones and fat to glucose—it's a process more than a singular or short-term event.

Learning more about fat-adaptation will help uncover all its potent health benefits and why achieving and maintaining it is essential to optimizing a low-carb, high-fat lifestyle.

  • Fat-adaptation is a longer-term transition that you shouldn't expect to occur overnight. It's taken a while to train your body to rely on glucose and other sugars in a state of carb-adaptation, and switching the body's inclination will require reformation.
  • No worries, the transition to fat-adaptation requires effort and intention, but the process is quite simple once you ditch the carbs and focus on eating loads of healthy fats.
  • Don't get us wrong, it's impossible to run the body without glucose, quite literally. However, although we will always utilize a mixture of fat, ketones, and glucose to function, our systems will prefer the former as their primary fuel source, using glucose sparingly and efficiently.
  • Many find that their appetite naturally dwindles once they've removed carbs and most sugar from their diet consistently for a couple of weeks.
  • However, there is no need for alarm. A standard signal of the body relying on fat over sugar is a decreased appetite and fewer if any pesky cravings—an incredible advantage if you want to lose excess body fat!
  • Heightened focus is something that most would welcome, especially as hectic as life is today. Thankfully, the body's increased ketone levels when in ketosis or a fat-adapted state improves mental focus and sharpness.
  • Expect to experience a sounder sleep once fat-adapted as preliminary studies indicate increased ketones aid in a more restorative slumber.
  • Increased and rapid weight loss is a benefit experienced by many, especially when getting started and on the road to fat adaptation. Plus, you'll notice that other notable bonuses shared above can work well in concert toward your fitness goals as increased energy and stamina lend toward engaging in a more active, healthy, and energized lifestyle.

While there are many benefits to reap once the body starts relying on fat and ketones for fuel, it's crucial to stay mindful to avoid mistakes commonly made by those new to the ketogenic diet.

Here are some notes to help to avoid a few commonly experienced side effects:

  • Keto Flu: Fatigue, brain fog, and intense breath may all act as evidence that the body is beginning to run on fat for fuel. Your body may have come accustomed to accessing glucose for frequent and short-lived bursts of energy, and weaning our system off sugar to convert to running on ketones and fat can pose some physical reactions.

    However, we can take simple steps to mitigate or avoid the common symptoms of the keto flu as the body adjusts to using fat as a primary energy source. Check out our dedicated article for all the tips needed to mitigate or side-step the initiation woes of the keto diet—possibly entirely.
  • Eat your macros: Restricting carb or calorie intake significantly may feel familiar if you’re a serial dieter, but skimping on your food intake can backfire! Focus on filling your meal plan with a wide variety of nutrient-dense, low-carb options and you’ll soon naturally eat until you're full, and nothing more, with ease.
  • Measure non-scale victories: Whether it’s easier to chase your littles around or you notice yourself achieving groundbreaking personal records in fitness, notice improvements happening apart from the scale for best perspective, especially during times when the scale may stall.
  • Drink your H2O: Water is essential for all, but drinking adequate levels is especially important for anyone following a ketogenic diet. Ample water intake and frequently replenishing hydration will aid in feeling your best as your body releases higher levels of water and other elements in the presence of increased ketone levels in the body.
  • Be patient and trust the process: Your body didn’t become attuned to running on carbs and tons of sugar overnight and our body’s need time to convert to fat-burners, too—no surprise there. However, it’s easy to feel antsy and anxious to become fat-adapted quickly, but no worries, there’s no need to rush.

Although it takes time, once achieved, fat-adaptation offers many health benefits and helps you better utilize and regulate how your body accesses and burns fuel—even improving our ability to manage insulin well naturally.

Plus, certain foods aid in fat-adaptation as they are rich in nutrients, low in carbs, and help you feel fuller for longer. Here are some notable foods to enjoy as you seek to boost ketone levels and achieve running on fat for fuel:

  • Coffee: We know you likely need little encouragement to drink a warm cup of java, but do so with a bit of added comfort as those aromatic roasted beans also aid in protecting against fatty liver disease.
  • Green tea
  • Bone Broth
  • Berries: Stick to blueberries, strawberries, and blackberries to keep your options on the low-glycemic side.
  • Avocado
  • Lemon
  • Unsweetened yogurt
  • Cottage cheese
  • Cheese
  • Broccoli
  • Kale
  • Collard greens
  • Turnip
  • Bok choy
  • Garlic: Plus, garlic enhances food's flavor and provides an anti-inflammatory effect.
  • Canned tuna or salmon
  • Unsweetened almond milk
  • Unsweetened coconut milk

Deficiencies can occur when eating any dietary style, and this remains true with a ketogenic diet. Our bodies release increased levels of fluid, vitamins, minerals, and electrolytes when in ketosis or fat-adapted, making it especially important to replenish nutrients and hydration on a low-carb, high-fat diet.

Plus, some can become obsessed with monitoring macronutrient intake (e.g., fat, carbs, protein, fiber, et al.) to the point of neglecting micronutrients (e.g., vitamins and minerals). And placing all the attention on curbing carbs and boosting fat while disregarding eating nutrients or drinking probiotic-rich foods to encourage digestive health may result in deficiencies and gut microbiome dysfunction.

Fortunately, there are many foods and beverages to enjoy to boost the gut microbiome: kombucha, pickles, kimchi, and bone broth are all keto-friendly items to consume for an abundance of nutrient-rich fare that also supports a healthy gut microbiome.

We've even dedicated a post to keto-friendly preserved foods that you may find handy to preserve your favorite meals of the season to enjoy throughout the year.

Timeline of Fat-adaptation

OK, so you've cleared your pantry and fridge of overt carbs and sugars, and you are coasting on fat for fuel. Great! Yet, you're probably wondering how long it takes to become fat-adapted once in a consistent state of ketosis. No worries, more on general adaptation timelines below.

First, you'll want to reduce your daily carb intake to 50 (total) or 20 (net) grams a day for between two and four days to enter the metabolic state of ketosis where the body ditches glucose for fat and ketones for its primary and preferred fuel source.

While factors like activity level, metabolism, and your personalized macros may impact the speed at which you enter ketosis, maintaining a carb cap can ensure remaining in the state steadily to enable the body to achieve fat adaptation.

While achieving ketosis can occur rapidly, fat adaptation is another matter. Of course, any process of transition or adaptation takes time by nature, and this journey is no different.

Most of our bodies have likely used glucose and other forms of overt sugar and fast-digesting carbs for energy for a while. Our systems need about four to 12 weeks to become fully adapted—with the body running optimally on fat and ketones and minimal traces of essential glucose.

Furthermore, endurance athletes and those who engage in significant steady-state activities throughout their day may enter ketosis faster. Their energy exertion forces the depletion of glucose stores more rapidly to expedite or deepen ketosis—a tool to potentially move the metabolic needle toward fat adaptation faster.

Plus, staying active or increasing activity are also excellent ways to support mental health while keeping toned as you shed the excess weight you may have packed on over the past year at home.

Ketosis vs. Fat-adaptation

Entering ketosis could result from fasting, starving, or experiencing the end-stages of pregnancy at a moment's notice—with unborn babies and their mothers entering the metabolic state more often nearing birth.

Plus, once we eliminate carbs and sugars—and ketone levels in the body flourish—the body begins its somewhat awkward switch in energy sources. Fortunately, eventually, we become fully adapted to using fat and ketones for fuel and utilize it optimally to support our highest levels of health if we stay the course and trust the process.

Signs of Fat-adaptation

Many of the signs and symptoms that one is fat-adapted are often anecdotal. More research is needed to understand all the nuances associated with fat-adaptation; although the apparent benefits appear hopeful.

Here are some of the most common benefits of those running on fat and ketones religiously:

  • Decreased cravings and hunger: Eating sweets and high-carb salty snacks may have ensnared you in the past, but rest assured that it's possible to live a life free from uncontrollable food cravings while enjoying every single bite along the way.

    Banishing cravings is quite common on keto; it's one of the diet's most valuable benefits for those wanting to lose weight on a low-carb, high-fat diet!
  • Improved focus: Whether able to complete tasks with ease or noticing longer spans of attention when engaged with others, an increase in ketone levels is known to sharpen focus and help with stamina, too.
  • Improved sleep: It's challenging to achieve deep and restful sleep if your body is unwell or experiencing forms of imbalance. Fortunately, metabolic ketosis provides a plethora of benefits that support overall wellness and optimal mind-body function.

Different Roads to Ketosis

Limiting carbs is always advised on any variation of the ketogenic diet. Still, there are subtle differences in the ways to approach the low-carb, high-fat diet that are worth considering as you journey toward fat adaptation.

The ketogenic diet relies on the primary goal of managing the intake of carbs, even using them to your advantage when timed in association with vigorous activity.

Here are the most common iterations of the ketogenic diet for review to help you identify which may work well for you:

  • Standard ketogenic diet (SKD): This option is an extremely low carb, moderate protein, and high-fat diet that often caps daily carb intake to 20 grams of net carbs or less. Starting out with the SKD approach is a great way to master the basics or perform a reset if you’ve veered off track.
  • Cyclical ketogenic diet (CKD): As we mentioned, timing carb consumption can work well, especially for athletes who need a targeted short-term boost of power.

    This take on the keto diet involves periods of higher-carb refeeds, also known as "carb-ups," often eating five ketogenic days followed by two higher-carb days.
  • Targeted ketogenic diet (TKD): Athletes and those who lead very active lives need to eat a diet plan tailored to their energy needs.

    Like a cyclical diet, a targeted approach to keto allows you to add additional carbs to your meal plan scheduled around workouts and is ideal for those living an active and vibrant lifestyle.
  • High protein ketogenic diet: Bodybuilders and those whose physical activities result in a significant "tearing" and repair of tissue greatly benefit from eating slightly elevated amounts of protein.

    A high-protein keto diet is like a standard ketogenic diet but includes—you guessed it—more protein! The ratio followed is usually around 60% fat, 35% protein, and 5% carbs.

Ways to Ease Adaptation

Every transition comes with its set of changes. Adaptation requires adjustment, and shifting the body's metabolic mechanism from carb-burning to fat-burning is a unique experience.

From encountering the 'keto flu' to your appetite curbing effortlessly before your eyes, there are tangible effects tied to becoming fat-adapted.

While the process of adjusting to a fat-adapted state poses a call for a commitment to cutting carbs, there are a few ways to lessen the effects of the transitory process, especially during week one.

Here are a few tips to keep in mind as you embark upon fat adaptation:

  • Boost salt and water intake: Again, our bodies release increased levels of fluid (water weight), salt, minerals, and vitamins when in ketosis, and it is vital to replenish hydration, nutrients, and electrolytes regularly to maintain adequate levels to feel your best. Salt your food and/or beverages with a good quality salt or take a daily electrolyte supplement.
  • Curb intense workouts: Engaging in extreme activities is an excellent way to re-establish ketosis quickly after a slip-up; you’ll empty your glucose stores swiftly causing the body to alternatively seek fat for fuel.

    But, a metabolic energy swap may leave you feeling a tad drained at first, as your body efforts to recalibrate from running on glucose to operating primarily on fat and ketones for fuel.

    But, you can remain active with a minor adjustment. Opt for low-impact, steady-state activity like walking or pilates instead of anything rigorous.
  • Eat loads of fat and fiber: Consuming healthy fat is always a goal on a ketogenic diet; it will keep you full and always satiated. However, incorporating fiber into your meal plan will prevent pesky problems like constipation and aid sustained digestive health—don’t skip it!
  • Improved Insulin Sensitivity: Consuming excessive carbs can cause the body to regulate glucose and insulin in the body poorly, but a keto diet can steer your insulin health in a positive direction.
  • Further Spaced-out Meals: Many note a reduced appetite as they rely more heavily on fat and ketones for fuel, along with needing to eat fewer times throughout the day.

    Don't be alarmed if you feel less hungry, eat smaller portions at each setting and your cravings virtually vanish once fat-adapted—it's par for the course.
  • Optimized Use of Fat for Fuel: While many experience growing pangs when transitioning to fat-adaptation, once settled, our bodies begin to run at peak performance levels and require refueling significantly less often.
  • Enjoy a Constant Fuel Source: Spikes and dips in energy are common when carb-adapted, which is why those relying on glucose for fuel feel the need to eat about every three hours when glucose levels drop and require frequent replenishing often to maintain current performance.

    However, you'll always have an ample and premium energy supply when in ketosis and fat-adapted as the body efficiently manages and produces ketone levels that are ever present when fat-adapted.
  • Burn More Fat During Exercise: Those relying on sugar to power through workouts are more dependent on fast-digesting sugars to boost their activities.

    However, those who are fat-adapted and easily able to work out in a fasted state or without the boon of high-glycemic carbohydrates can tap into fat stores for fuel and burn excess amounts of stored, even visceral, fat—resulting in safe and often rapid weight loss in areas of the body most essential to health (e.g., about the abdomen).
  • Enjoy Metabolic Flexibility: Our bodies need glucose. Some levels of sugars are necessary for the body to operate brain and bodily function properly. However, an excess of glucose or jamming our system to the point that it no longer regulates insulin signals may result in metabolic disorders like type 2 diabetes and insulin resistance.

    However, the body can most efficiently use fat, ketones, and glucose to best fuel the body based on its present needs and demands once it adapts to using ketones and fat as its primary fuel source.

    What’s even better is that the body learns to run on fat and ketones primarily for steady-state premium energy, but it can fluidly access glucose efficiently when and as needed, as well. You get the best of both worlds!


While there's a process to becoming fat-adapted, it is well worth the effort!

Have you let go of carbs and notice it's easy to go three hours or more without eating? Is your midday desire for a nap a self-care indulgence rather than a desperate attempt to refill your tank to barely make it through the day? Can you knock out an effective workout without loading up on carbs before your session and have the brain fog and headaches possibly experienced in the first weeks on keto passed?

Good news, you're probably fat-adapted!

Continue to enjoy foods filled with delicious and nutritious healthy fats, mind your macros, micros, and hydration, and enjoy the benefits of arguably the most coveted prize of following a low-carb, high-fat diet: running optimally in the ideal and flexible metabolic state of fat-adaptation.


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