Metabolic Flexibility: what is and how it affects your health, energy and weight.

Ketones are for the brain like kerosene is for the jet plane & metabolic flexibility is like having overdraft protection.

Glucose on the other hand is like gasoline, not good for the jet plane but good for the car.

What kind of brain do you own?

  • Jet plane like brain or a car like brain? Keep riding, you’ll be able to answer this question at the end of the article. (HINT: there are places we can only get by car and places where we can get a lot faster by jet plane).

Let’s get back to how our body uses stored energy.

NOTE: If you didn’t read part one Metabolic Flexibility, what it is and how it affects your energy, health and weight, click here.

How we generate energy in the absence of food is a bit more complicated to understand, but not impossible.

  • Glycogen is used up first and remember, the glycogen tank is rather small and it empties pretty fast.
  • Fat on the other hand, holds a lot more energy, but it’s not that easy to tap into it, unless….you are metabolically flexible (I’ll explain what that is so don’t worry).

When your body receives food frequently, and in particular, food that comes with a generous amount of carbohydrates (aka sugar), finds itself in a state of abundance, and it keeps burning food, not stored energy as fuel.

  • In fact, most of us keep storing the excess energy coming from food, as fat (energy that goes into the “unlimited” reservoir = adipose tissue) and rarely, if ever, do we get to use it as fuel.

The bank account analogy is best. If you get money often (let’s say from paychecks, gifts and inheritance), you get so much money, that you can’t possibly spend it all, what do you do? You put the extra in a saving account.

  • That’s exactly what your body does with the excess energy coming from food: it stores it (mostly as fat).

When it comes to your bank account the bigger the savings the better. However, when it comes to your body, the bigger the fat that is stored on your body, doesn’t mean better health or energy. Quite the opposite is true.

Your metabolism wants what’s easy and convenient. 

  • Why spend money from savings when money keeps coming in, right?
  • Why burn saved energy (glycogen or fat) if energy comes from food?

This however, when it comes to metabolism is not good, because the metabolism gets “lazy”.

It down regulates the enzymes that are needed to convert saved energy into usable energy and it leads to “metabolic stiffness”. (This metabolic process it’s known as beta oxidation of fats. It takes place inside the liver’s mitochondria and the end products are called ketone bodies, aka “kerosene”).

This “metabolic stiffness” translates into the inability to quickly and easily make energy in the absence of food, or carbs.

In other words you crash, you crave, you’re tired and you “hit the wall”.

The question is what kind of metabolism do you want?

Yes you have a choice!

  • Lazy, stiff metabolism or industrious and flexible.
  • Do you know what kind of metabolism you have right now?
  • Do you know that It’s entirely up to you what kind of metabolism you posses?

Your body learns very quickly that:

  • it’s easy to burn sugar coming from the diet,
  • it’s a bit harder to break down glycogen (stored sugar) and
  • it’s a hell lot of work to bring out the fatty acids from the fat stores and then to convert those into usable energy, primarily for the most “energy hungry” organ, the master computer: your BRAIN.

Yes! When the metabolism is asked to, (not to say forced to) it can get efficient and flexible and it can burn that stored fat and convert it into fuel (aka ketone bodies=kerosene), which can travel through the Blood Brain Barrier directly to your incredible brain, and keep it fueled, so you are both happy.

Remember the person that lived on it’s own stored energy for 382 days? In order to do that, he developed a very flexible metabolism. 

  • Clear thinking,
  • Abundant mental and physical power,
  • Sustained energy,
  • Normal hunger,
  • The absence of food cravings,
  • Optimal body weight and body composition,
  • Well controlled blood sugar,
  • Insulin sensitivity,
  • Low triglycerides and improved lipid panel.

Are just a few of the “signs and symptoms” of a flexible metabolism.

I think the biggest win of MF (metabolic flexibility) is not feeling uncontrollably hungry, “I will kill someone for food” kind of hungry, despite the fact that you didn’t eat perhaps since breakfast and it’s almost dinner time.

Oh and did I mention that you still have plenty of energy, you are sharp like a hawk?

Yes I did. Well, reiteration never hurts.

Now the opposite is also true and in fact, is far more common today. That is: your metabolism decides to become rigid, (with your support of course).

Don’t feel bad. This is in fact good news.

You can change you!

The only variable you have full control over is “YOU” and your metabolism.

Most of us today have a very rigid metabolism.


  • Lack of metabolic understanding combined with a “food-centered” culture.
  • The “21st Century Man” eats every 2-3 hours thinking that if he doesn’t gets in “starvation” mode and that will slow down the metabolism, and terrible things will happen….

Somehow we forgot how we survived and thrived as species here on planet earth, (HINT: prolong periods of fasting and food scarcity were kind of the norm…).

  • The fact is that we live in an environment that’s dramatically different than that of our ancestors.
  • An environment that doesn’t match our genetic makeup. And because of this environment, which allows for easy access to food, we managed to pushed our metabolism from flexible to rigid.

Unlike the bank account, when the biggest the savings the better is for you and your life, when it comes to your body, the biggest the fat savings the worst it is for your health. I know you already know that…

I will repeat:

You have full control over your metabolism.

Now let’s see what does it mean to have a flexible metabolism?

  • In short FM, allows for the use of both fuels as energy (glycogen and fat).
  • It switches effectively from oxidizing glucose to oxidizing fat. That’s why we say it’s flexible.

How does it do that?

  • Food availability determines your MF.

If you happen to skip a meal,

  • a flexible metabolism will facilitate fat oxidation and
  • will supply the brain with the “alternative” fuel: ketone bodies,
  • without you being aware of the change in fuel, without you hitting the wall, crashing, losing focus, dropping energy, having uncontrolled hunger, or cravings, etc.

It is like having the overdraft protection for you bank account.

Metabolic Flexibility = Overdraft Protection

It is like paying the bills on time, and not having your phone or electricity cut off, even if you don’t have enough money in your checking account. You are always protected by the overdraft protection.

A flexible metabolism makes sure there is always available fuel to the brain.

NOTE: today due to our diet and lifestyle glucose became the primary source of fuel and ketones are considered the “alternative” fuel, but that wasn’t always the case. The ancestral man spent most of his days in a mild ketotic state. They were effective fat burners with a very flexible metabolism.

  • Your brain is the one and single organ that if it has fuel available you are happy. You have no food cravings and in fact, you have endless energy.
  • Your brain is happy with either fuel:-glucose or ketones.
  • Biohack tip: it operates at a higher speed and gets an upgrade when running on ketones.

Remember ketones are like kerosene? Jet plane fuel.

Do you want to run your brain like a jet plane?

  • Develop MF and you’ll run your brain and body just like a jet plane.

The problem arises when the glucose supply is getting low and the ketone bodies are not available.

  • That’s when your brain starts to send you emergency messages and you get shaky, irritable, extremely hungry, etc.
  • That’s when you “hit the wall”.
  • That’s when: the diet” stops working.

This is why diets fail.

  • Not because you are lacking will power,
  • Because you are lacking metabolic flexibility and
  • Your brain has access to only one fuel: sugar.
  • When sugar drops you crash and crave.

“You can’t use willpower to fight against a fuel deprived brain. It is like wanting to hold your breath when you are indoors and breath only when outdoors. It’s physiologically impossible.”

  • It is impossible for you not to feel extreme hunger and not to have cravings if the brain is deprived of fuel.

How do you go from metabolically stiff to metabolically flexible?

How do you go from burning sugar to burning fat?

How do you go from always exhausted to never tired (just like the 5 year old)?

These are a million dollar questions. Don’t panic! I have the answer, and you don’t have to give me a million dollars to find it.

Once you know the answer to this question, you become free.

  • Free of food cravings.
  • Free of ravenous hunger.
  • Free of food obsession.
  • Free of energy crashes.
  • Free of many prescription and over the counter drugs.

You become the best version of yourself.

The upgraded you.

You experience a whole other level of BEing and DOing.

The answer is simple:

  • eat less carbohydrates
  • eat less often (aka fast from time to time or skip a meal or two)
  • eat more fat and
  • don’t eat more protein, in fact keep it on the low side (don’t fall for Paleo)

The implementation, perhaps is not as easy.

At the beginning it’s hard, it’s really hard. I won’t sugarcoat it for you.

But once you get that MF going, you are in for a ride, you get an unfair advantage and you really feel like you are not human.

What do I mean by not human?

Most, if not all humans you know,

  • Need to eat a lot, and often. You won’t.
  • Complain of being tired. You won’t.
  • Have food cravings. You won’t.
  • Struggle to lose or keep a healthy weight. You won’t.
  • Take 2 or more drugs to manage dis-ease. You won’t.

You’ll go for long periods of time without eating or thinking about eating and not feeling a drop in energy. In fact, you’ll have more energy than ever before.

That’s when you start to question your human state:)

I know it sounds strange that the less you eat the more energy you have, the better you’ll feel the longer you may live. I will leave the explanation of how this is possible for another blog post.

  • For a mind blowing story of an average woman, turning into a super-woman, and her endless physical energy, click here.

One  conclusion:

What makes it a success or a failure is your BRAIN and your MIND.

  • #1. How you think and what you think determines how you act and how you follow through. Power-up your brain with loads of empowering belief. e.g

eating4energy = easy and is within my reach

  • #2. Your brain is the energy sensor of your whole body.
  • #3. Your brain can use glucose and ketones as fuel. Little dirty secret: it loves using ketones as fuel. It’s your job to fuel your brain with the best fuel possible.

#4. Your brain is a carbohydrate-dependent organ ONLY for as long as you continue to eat a high carb diet.

Make a change today!

Pick one and go do it (see suggestions below), then pick one more and so on, all the way until one day your metabolism is flexible (again) and you feed your brain the “alternative” fuel, so you feel good all the time, and you heal from the inside out.

Here’s what you can do:

  • cut sugar out, completely,
  • cut back on the amount of carbs you eat (hint: go gluten and grain free, go starch free),
  • choose the lower glycemic impact fruits (e.g go for organic berries),
  • eat the rainbow of vegetables (all the non starchy colorful vegetables
  • just eat less often (aka Intermittent Fasting)

When you do all these you can eat more fat, because now you burn FAT.

  • Your own stored fat, or the fat you consume!

Keep it simple:

  • change what you eat,
  • how often you eat and
  • make sure you eat whole foods, so you nourish your body.

Now you know how you get metabolic flexibility. It’s not a strange yoga pose you need to learn and do.

Now you understand that it’s all about the fuel that’s available to the brain.

I love this analogy.

Glucose as fuel is like the gasoline. It can be used for the cars, but the jet plane needs the ultra-fuel because the gasoline is not good enough (it burns too fast).

Ketones on the other hand are like kerosene, the fuel used to fly jet planes (it burns slow and effective).

What do you want to be, a car or a jet plane?

  • Glucose = gasoline = good to run a car = stiff metabolism
  • Ketones = kerosene = best to run a jet plane = flexible metabolism
  • Ketones + Glucose = flexible metabolism

It’s your choice. You create your own reality. Deliberate or by default.

To recap:

  • metabolic stiffness = only one fuel is available (glucose) = crashing or hitting the wall, cravings, etc. hence to prevent that requires frequent eating
  • metabolic flexibility = two available fuels, with ketones taking over when glucose drops = endless energy, hence requires less frequent eating.

Now, going back to what happens in your day to day life.

I’m not telling you not to eat regular meals.

You have to do whatever works for you. You are the expert in “YOU”.

From time to time pause and ask yourself,

“How’s this working for me?”
“How’s my energy”?
“How’s my health”?
“Can I change anything to get even better?

What do I want to run like?

  • A car?
  • A jet plane? Or
  • Both.

If you answered BOTH, you have the correct answer. When you run like “both” you have metabolic flexibility. There are places you can’t get to by jet plane and places you can’t get to by car. Being able to switch from one to the other is like switching from burning sugar to burning fat, or like switching from burning food to burning stored energy (primarily your own fat).

If you have a life that’s very steady, scheduled, and regimented and having breakfast, lunch and dinner at regular intervals of time works for you, then go with it. Your body, likes routines and may work just perfect for you.

If that’s not the case and

  • you have to run all over the place, all day every day,
  • you attend long meetings,
  • you want to run a marathon,
  • you want to lose weight, you’ve tried it all and nothing worked long term,
  • you want to manage blood sugar, or other metabolic disorders with diet and lifestyle, or
  • you simply want to maximize the way your body produces energy and to have endless energy,

Then you may want to look into developing metabolic flexibility.

There’s power in knowledge. Get to know your body.

Understand how it works. Take actions.

  • Understanding what’s happening metabolically when you have lots of energy versus when you feel fatigued and tired, it may be all you need to feel empowered to take actions.
  • Knowledge is power and when you understand how the body works it becomes easier to try something new that perhaps goes against conventional wisdom.
  • Give yourself permission to try something different and see how it works for you.

Final thoughts.

It’s nice to sit down and have a meal with your family. This bonding time around food is extremely important.

By changing the way you look at food and think about food as a “fuel”, as a “powerful medicine”, “as information” that communicates with your genes, you can choose differently.
You can optimize it, so it really supports your goals whether you want to prevent, reverse disease, or improve physical, or mental performance.

For the video version of this blog post you can watch the video below.


Do you want to learn more about how a whole foods, low carb diet can heal your body and optimize your metabolism, (e.g. have incredible energy, lose body fat, be happy and pain free)? Then join the Healing with Foods Community, both on email, as well as, the Private FREE Facebook Community.

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We all know that diets don't work; deprivation and denial are both unnecessary and counterproductive. When it comes to food and your health ignorance is not bliss. I'm Mihaela and I will help you find what is holding you back from living your best health and life, simplify your eating and fitness routine to fit your busy schedule, learn to listen to your body, deconstruct cravings so you can make food choices that truly nourish you. I will help you break complex information into bite size pieces, easy to implement so you can take action now. Take charge of your health and live your best life ever.