Metabolic Flexibility, why it gives you an advantage


Metabolic flexibility is the ultimate health aim.  It gives you a big advantage for sustainable and lifelong metabolic health.  Metabolic flexibility helps you think clearer, stabilise your weight and increase your energy.


So, what is it?


Metabolic flexibility is about switching between all the fuels available to you, for dealing with stress, exercise, writing that big report, remembering things and doing all the things you love to do.  The fuels available to you include;

  1. Glucose
  2. Fats (stored and dietary)
  3. Ketones; and
  4. Sunlight

So how do you become metabolically flexible?  Through;

  1. Ketosis
  2. Cycling carbohydrates
  3. Fasting
  4. Building muscle
  5. Getting sunlight

Fuel sources

The energy your cells create, not only run all your automatic bodily functions, but also allow you to think, move, drive, eat, instruct to your kids and husband, and communicate with your environment.


Ketosis is a metabolic state where your body or specifically your mitochondria are using the electrons from ketones and body fat (fatty acids) as their main fuel to produce energy, instead of glucose or sugar from your diet.   Most people eating a high carbohydrate western diet are only using the electrons from glucose as their primary fuel source.  This article will outline the metabolic advantages of being able to switch between using ketones, fatty acids, and glucose  as a way of producing energy.  We can’t forget sunlight in this process.  Sunlight makes it all work efficiently, no matter what fuel you are using.


The body has an amazing ability to switch between several different fuel sources to supply you with energy, depending on your needs.  The two main energy sources available from food are carbohydrates or fats.  Protein only plays a small part, through a process called gluconeogenesis, creating glucose from protein.


Using carbohydrates for energy

The main fuel source used by people eating a high carbohydrate western diet is glucose.   All carbohydrates (starches and sugars from plants) are created by sunlight through a process of photosynthesis, and include grains (wheat/rice/barley/rye); nuts and seeds; and fruits and vegetables. These foods are ultimately converted to glucose in the body and used to fuel our cells, including the brain.


Glucose is burned by the body quickly. It is like putting kindling on a fire, it burns fast and you constantly have to add more fuel to keep the fire alive.


Using fat and ketones for energyKetones and glucose

When dietary carbohydrates are low;

  • Below 50 to 20 grams per day, and
  • Your intake of natural fats is high, or
  • You have not eaten and your insulin has gone back to baseline, then your body will start to use either the fat you just ate or stored body fat for fuel.

Your liver will also convert some of your stored body fat into ketones, which can be used by the brain, when insulin is low.  Your brain can be powered by both glucose and ketones, which becomes very important for your brain if it has become insulin resistant or you feel foggy.  The electrons from fat and ketone are a very efficient and clean fuel source and can give you up to 4 times more energy production than glucose.


Burning fat as your fuel, is like putting a log on the fire, it will burn slower and longer at a steady rate.


The hormone Insulin

In relation to energy metabolism, insulin’s main role includes; helping glucose enter our cells so it can be used as fuel, and as our fat storing hormone for excess glucose. When we eat carbohydrates, we have an insulin response within about 30 minutes, then it will take about 2 to 3 hours, in a healthy person, for insulin to go back to baseline.  If we constantly snack then our insulin levels remain high, even if our blood glucose looks normal.


While insulin is high the body cannot produce ketones or burn body fat for fuel so we become metabolically inflexible to utilizing these other fuels.


Normal insulin response, after a meal, for a metabolically healthy person.

Insulin response three meals a day


Insulin response with snacking throughout the day.  Every time you eat, your body has an insulin response which will stop you from burning fat and causes inflammation.

Insulin response from snacking


MitochondriaSunlight and mitochondria

Your mitochondria are very important little organelles, located in your cells, and are your energy powerhouses.


Interestingly, mitochondria are actually ancient organisms, that have their own DNA (as opposed to the nucleus DNA), which you inherit from your mother (occasionally from dad).  They communicate with the environment, including light, and can influence the expression of the nucleus DNA when it comes to energy metabolism.  Some cells  have a few mitochondria and others can have up to 600,000 such as egg cells.  Red blood cells have no mitochondria. The mitochondria take the electrons from your food, sunlight, and oxygen and convert them into Adenosine Triphosphate (ATP), the energy your body runs on.


Advantages of using ketones and fat

4 times the energy

Electrons from ketones and fat provides your body with 4 times the amount of energy, then glucose does.  If you could take advantage of this ketogenic state, you could have 4 times the amount of energy you need to do all the things you love and then some.


Cleaner energy source

Ketones and fats also provide a cleaner source of energy.  All energy production generates pollution, whether from a car or a power station.   In your body this pollution is called Reactive Oxygen Species (ROS) or free radicals.  Free radicals can cause inflammation.  However, when your body is working optimally, the body goes into housekeeping mode during sleep through a process called autophagy and cleans out the inflammation.

Unfortunately, glucose is not as clean and may cause more free radical damage than fats and ketones. If you are constantly snacking on high carbohydrate foods, you are placing a large burden on your body to clean up afterwards.  Poor sleep impacts autophagy or repair and can lead to health issues in the future.


Metabolic flexibility and our ancestors

The ultimate aim is to become metabolically flexible so you can switch between these different fuels, depending on the time of year, latitude or your immediate needs such as running from a tiger and hunting (Or modern-day tigers and hunting such as kids not getting ready or your boss putting giving you too much work).


During spring and summer, our ancestors would have enjoyed both animal protein, as well as abundance of plant foods.  Information from the sun allows plants to grow in abundance during these seasons.  At the end of summer, our ancestors may have come across a fruit tree and gorged themselves, building fat reserves for the winter ahead.



During winter, they would have eaten what was available; mainly animal protein and fat.  They would have cycled into ketosis during the winter or whenever food was scarce.

The body stores about 12 hours’ worth glucose in your muscles and liver, in the form of glycogen.  Reserves for fight or flight.   However, we have months’ worth of fat stores.  During times of scarce food availability, our ancestors would have struggled if their only option was to use glucose as their primary fuel.   Lucky there is a metabolic switch that helped them through the winter, in the form of ketosis.


No winter for modern humans

Unfortunately, our modern life does not allow for a winter in relation to food availability.  We can eat 24/7 if we want to.  We don’t have to wait for something to be in season or even grow in our region.   We also have abundance of highly refined foods made from carbohydrates, industrial seed oils and chemicals.

This abundance of high carbohydrate foods makes it hard for us to take advantage of this ketogenic state, where we can burn our fat stores for fuel.


Tools to help us become metabolically flexible

The tools we have available to take advantage of metabolic flexibility include;

  • Cycling in an out of ketosis using the ketogenic (keto) diet,
  • Fasting,
  • Getting enough sunlight and nature, and
  • Building muscle by lifting heavy things.

Cycling Ketogenic way of living

The ketogenic diet is a way of eating and living that can help reduce inflammation, clear the mind and brain, and stabilize weight.

Ketogenic way of living includes;

  • Cycling your food choices, depend on the season and your latitude
  • Getting up and seeing the sunrise, to set your circadian rhythms
  • Going out into nature during the day as much as possible
  • Adding animal protein to your diet; seafood, beef, poultry, eggs, lamb, pork etc
  • Eating abundance of seasonal vegetables that grow in your area
  • Adding natural fats such as; Lard, butter, beef tallow, coconut oil, olive oil, avocado oil, duck fat,
  • Nuts and seeds
  • Quality Water
  • Eat until satisfied, then stop eating
  • Leave at least 5 to 6 hours between meals. No snacking.
  • Do not eat close to bedtime
  • Build muscle through lifting heavy things, plus lots of walking

Note: Hunger and cravings will start to subside as you will be satiated by the sunlight, fat and protein.


Does not include;

  • Fake highly processed foods
  • Sugar, in all it’s forms
  • Industrial vegetable and seed oils
  • Grains, refined or not
  • Excess artificial blue light from devices

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