A very low-carb, high-fat ketogenic diet may offer a variety of health benefits, including increased energy, weight loss, improved mental function and blood sugar control. Fat adapted is one of the many terms associated with this diet, but you may be wondering what it means.
This article explores fat adapted, how it differs from ketosis, how long it takes to become fat adapted, and its signs and symptoms.
What Is Fat Adapted?
Simply put, “fat adaptation” is the metabolic state your body is in once you’ve been in ketosis long enough that your body has effectively transitioned from burning carbohydrates/sugar for energy to burning fat from food, fat produced by your body, and energy from your stored body fat reserves.
When you first start the keto diet and greatly reduce your carbohydrate intake, your body goes into high gear, burning off all of your remaining carbohydrate and glycogen stores. Then, when carbohydrates are no longer an option, it begins to tap into your excess fat stores for energy. After four weeks or more, your body begins to get used to living off of fat, or becomes fat adapted.
In this state, you’ve largely lost your carbohydrate cravings, feel fuller faster at meals, and stay fuller longer, which motivates you to eat less and still feel great. You’ll also find that once you’ve adapted to the fat, if you happen to consume a higher carbohydrate one day, it won’t affect you or your ketone and blood sugar numbers as much as it would if you were transitioning from a high-carb diet.
Fat Adapted vs. Ketosis vs. Keto Adapted
Now that you know the basics of fat adaptation, it’s time to clear up some of the misconceptions surrounding fat adaptation and the ketogenic diet before we move on.
The ketogenic diet is very popular right now, and it has recently received a great deal of scientific support. As a result, there has been some confusion regarding terminology and their definitions.
While the keto diet works well in increasing fat burning, it is far from the only way to become fat-adapted. You can burn a lot of fat without going through a keto diet. For example, intermittent fasting and other forms of calorie or carbohydrate restriction can improve fat burning, as can exercise.
Also, ketosis and fat adaptation are not the same thing. A state of ketosis occurs when you restrict your carbohydrate intake and your liver begins to produce ketone bodies. Although ketosis is associated with greater fat burning, entering ketosis is not necessary for fat burning or fat adaptation. Significant fat burning can still occur without any ketone body production. While entering ketosis may be good for your health, it also does not necessarily ensure that you will achieve your weight loss goals.
Finally, you may have heard the term ” keto-adapted”. Keto-adapted means that your body has become accustomed to the keto diet and you have passed the “keto flu” stage. If you’re keto-adapted, you’re following a keto diet; You’ re in ketosis, and your body is at least partially adapted to fat.
However, if you are not on a keto diet, don’t sweat it. You can still become highly fat-adapted.
How Long does It Take to Reach Fat Adaptation?
Generally speaking, it takes 30 days to 12 weeks to become fat-adapted by sticking to a keto diet. During this time, you’ll want to focus on clean, whole foods and stick to a ketogenic diet without cheating or deviating.
First, you’ll go through the initial phase: carbohydrate withdrawal, which will last 3 to 14 days and is characterized by cravings, hunger, and perhaps keto flu.
Then, you’ll move directly into the second phase, where your body adjusts from relying on glucose for energy to relying on fat, which can last 6 to 8 weeks. After a few weeks, your body is on fat-burning autopilot, and you’ll stay that way as long as you maintain a keto lifestyle.
Fat Adapted Signs and Symptoms
While the signs and symptoms of fat adaptation are largely anecdotal based, many people report that they experience fewer cravings and feel more energized and focused.
The onset of fat adaptation is not well described in the scientific literature, although there is some evidence that it exists in endurance athletes.
While there are some studies showing these effects, they are limited to a 4-12 month timespan. Therefore, comprehensive, long-term studies on fat adaptation are needed.
Decreased cravings and hunger
Keto enthusiasts claim that a reduction in appetite and cravings is one of the hallmarks of fat adaptation.
While the hunger-reducing effects of ketosis are well documented, the duration of this state varies from study to study. Therefore, there is insufficient scientific evidence to support the claim that fat adaptation definitively reduces cravings.
One study often cited by keto enthusiasts involved 20 middle-aged adults with obesity who were placed on a controlled, phased diet for 4 months. Notably, ketosis in that study was the result of combining ketosis with a very low-calorie diet.
This initial ketosis phase allowed only 600-800 calories per day and lasted until each participant lost their target weight. Peak ketosis lasted for 60-90 days, after which participants were placed on a diet containing a balanced macronutrient ratio.
Food cravings decreased significantly over the course of the study. More importantly, during the 60-90 day ketogenic phase, participants did not report the typical symptoms of severe caloric restriction, which included sadness, moodiness and increased hunger.
The reason for this is unclear, but the researchers believe it may be related to ketosis. These findings are compelling and warrant further study in a larger population.
However, you should keep in mind that extreme calorie restriction can damage your health.
Increased focus
The ketogenic diet was originally designed to treat medication-resistant epilepsy in children. Interestingly, children are more capable of using ketone bodies for energy efficiently than adults.
Ketone bodies, specifically a molecule called beta-hydroxybutyrate (BHB), have been shown to protect your brain. While not entirely clear, the effects of BHB on the brain may help explain the increased attention reported by long-term ketogenic dieters.
Again, more studies are needed on this effect and its relationship to fat adaptation.
Improved sleep
Some also claim that fat adaptation can improve your sleep.
However, studies have shown that these effects are limited to specific populations, such as morbidly obese children and adolescents or people with sleep disorders.
A study of 14 healthy men found that those on a ketogenic diet experienced deeper sleep but reduced rapid eye movement (REM) sleep. REM sleep is important because it activates areas of the brain associated with learning.
As a result, overall sleep may not have improved.
A different study of 20 adults found no significant correlation between ketosis and improved sleep quality or duration.
Therefore, further studies are necessary.
The Bottom Line
Fat adapted is a long-term metabolic adjustment to ketosis, a state in which your body burns fat as fuel instead of carbohydrates. It is often referred to as one of the benefits of the keto diet.
Fat adapted is said to result in fewer cravings, higher energy levels, and improved sleep. It may also be more stable and effective than initial ketosis.
Nonetheless, more studies are needed to determine not only the long-term effects of the keto diet, but also how fat adaptation works.