The keto diet is all about causing your body to switch from using glucose to using fat for your immediate energy needs. This process of becoming fat adapted on keto will take some time. You’ll want to know when you’re no longer depending on glucose for energy and are now burning through your fat efficiently. This is known as being fat adapted on Keto.
Once this important process is triggered in your body it can take anywhere from a few days up to a week or so to become established.
Factors such as your previous time spent on the keto diet, how strict you are with your carb allowance and your level of activity will all affect how quickly this is going to happen for you.
The aim of the keto diet is to get you into a state of ketosis.
On a carb heavy diet your body will choose to metabolize carbs first as this is the easiest way of converting the food you eat into the energy you need.
When your body has insufficient carbs for its immediate energy needs it will switch to its second metabolic pathway.
This will cause your body to use your fat stores for energy. While doing this your body will produce ketones, which gives the keto diet it’s name.
It is while being in this state of ketosis that you will be able to access the weight loss and health benefits of the keto diet.
To enter the state of ketosis will be your first aim on the keto diet, and this process should normally be complete within the first week.
That’s assuming you’ve been strict about keeping your carb intake to 20g net or less each day.
At this point you will have made the metabolic switch to burning fat and as your body becomes more used to this, it will be able to do so with greater efficiency.
It will be then that you will be fully fat adapted, a process that can take up to six weeks. You will begin to feel all the health and well-being benefits of the keto diet.
There are many signs of this process that is taking place in your body, and we will look at them here:
This is very often the first sign you will notice, as this sign will appear very quickly after reducing your carb intake.
This is due to the fact that lower carbs will help to stabilize your blood/sugar levels.
However, as you become more fat adapted, this effect will increase.
It’s not unusual for keto dieter to have to keep track of how much they eat as it becomes much easier to under eat by mistake.
You will feel full for longer, and the need to snack will diminish.
This study found that when their participants were ketotic, the weight loss induced increase in the hormone ghrelin was suppressed. Ghrelin is a main trigger for feelings of hunger and of wanting to snack.
Feeling full even if you are eating less than normal
Fat is very satiating, and has the ability to make you feel much more full than low fat foods.
It is also able to make you feel full for longer that carb based meals.
As you are now using fat for fuel, either from your food or your own stored fat, your body will be feeling the benefits of having a steady supply.
The keto diet with its emphasis on eating about 70% of your daily food as fat, helps with this process.
Being in ketosis (fat burning) increases the amount of cholecystokinin that you produce.
Cholecystokinin (CCK) is released rapidly into the circulation in response to a meal. The greatest stimulator of CCK release is the presence of fatty acids and/or certain amino acids in duodenum. (1)
After a meal, secretion of cholecystokinin activates the satiety center of the hypothalamus in the brain so that the person feels full and stops eating.
Increased fat loss
This is due to the fact that when you eat a very low carb diet, you are not producing spikes in your blood/glucose levels.
When blood/glucose levels increase, the body responds by increasing it’s output of the hormone Insulin.
This is necessary because to remain healthy, glucose levels in the blood must remain within a very tight window.
One of the main duties of Insulin is to trigger the storage of fat. Obviously not something that you are wanting to happen in your body.
When levels of insulin are low, your body does not go into storage mode.
You will now have more stable circulating nutrients that can be used for your daily energy needs.
Increased energy with reduced daytime sleepiness
When your body is metabolizing glucose for energy, it has to depend upon a fluctuating amount of available energy at any one time.
It will all depend on when you last ate, how active you have been and on how many carbs you have eaten that day.
Once you are fat adapted, your body will have a much more stable and regular supply for its daily energy needs.
This is because your body will use either the fat from your food, or your stored fat supplies.
This has the effect of giving more energy, and in a much more level way. There won’t be times in the day when you feel sleepy, especially after meals.
You will also find that you have greater endurance for your exercise or gym sessions.
Many keto dieters find that they are able to sleep for longer and with better quality sleep.
A Swedish study found that children who were being given a keto diet to help with drug resistant epilepsy, slept better and experienced more REM sleep.
They suggested that the brain chemical adenosine, which is important for sleep regulation, is increased in response to the keto diet.
This chemical helps to relax the nervous system and also reduces pain and inflammation – all factors that would also contribute to a good nights sleep.
Improved cognitive function
There is overwhelming evidence that burning fat for fuel is able to increase mental alertness and focus.
Most people feel very much more alert and with sustained levels of energy throughout the day once they’re in ketosis.
The keto diet has been found beneficial for many neurodegenerative diseases, and it is often reported that there is a decrease in anxiety and the level of depression.
Increased ability to cycle in and out of keto
Cycling through weeks of keto dieting interspersed with periods of low carb or regular eating is practiced by a lot of people as a way of maintaining their weight.
By doing this, they are able to build in more flexibility about the types of foods they can eat.
If you have been on the keto diet for some time and are well adapted to fat -burning, then this could be an option for you if you really do need to eat something off the keto food list from time to time.
You will need to be well fat-burning adapted first though, as you will be asking your body to switch between metabolic states, and you need to be able to do that easily.
So spend at least a few weeks, or better still a month on the regular keto diet before building in your carb days.
If you don’t do this, you may well find that you become tired and stressed on the days you switch back to keto.
For more information about keto cycling see keto cycle diet vs keto diet.
Ability to discover your personal carb limit.
The keto diet suggests that you eat 20g net carbs or less each day. However, your personal limit for ketosis may be quite a bit more generous.
There are ways that you can discover your own carb limit and it is discussed in more detail here how to work out your own carb limit for ketosis
If you are very keto adapted and can switch to burning fat easily, you will be able to increase your daily carb allowance and still stay in ketosis.
This will make staying on the keto diet and benefiting from it very much easier.
Once you’re in ketosis, you are burning fat for fuel and will be gaining many of the health benefits that the keto diet has to offer.
While you have adapted to using fat for fuel, you will not be fully adapted yet, and your body will need a little extra time to completely adjust to this new way of finding the energy it needs.
This takes some time and work, but it is well worth the effort to get there.
Within six weeks, your body should have fully adjusted to metabolizing fats, and you will feel many of the health benefits of the keto diet at this time.
Being fully fat adapted on keto means that you can easily follow keto cycling, or find your own carb limit while staying in ketosis.
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