Oxidative Priority: The Key to Unlocking Your Body Fat Stores

To lose weight — and keep it off — it’s critical to understand how fat loss happens in your body. 

To help you optimise your fat loss journey, this article will teach you everything you need to know about oxidative priority (the order in which you tend to burn the fuels available to your body). 

Unfortunately, because your body loves to store it, your body fat is last in line to be used.  However, by intelligently managing the upstream fuels — like carbs, fat and alcohol — and giving your body what it needs, you can ensure your unwanted body fat is used sooner rather than later.   

This ‘secret’ is the foundational principle of Data-Driven Fasting and our Macros Masterclass has helped thousands of people troubleshoot their diet to achieve sustained weight loss.  

BONUS: Download Free Data-Driven Fasting Book That Helped Thousands Of People Personalize Their Fasting Routine

What is Oxidative Priority?

Oxidative priority, or oxidative hierarchy, is simply the order in which we tend to burn fuels like alcohol, ketones, glucose, protein, and fat available to our bodies. 

Imagine if you poured crude oil on the ground, poured petrol on top and lit a match (please only imagine; don’t try this at home!).  The petrol would burn off quickly, and the oil may not even ignite.  Oil burns slowly, while petrol burns quickly. 

Volatile fuels like gas are hard to store.  In contrast, it’s much easier to store large amounts of energy as unrefined crude oil.  In addition, the more we refine these fuels, the faster they burn. 

In a similar way, the foods you eat behave differently in your body depending on their degree of processing and their macronutrient profile.  

The fact that different macronutrients are harder to convert, and there are more significant losses in their conversion, is a highly underappreciated food parameter that goes by several names, including:

The Order Your Body Uses the Food You Eat

The food we eat contains macronutrients that behave uniquely in your body.

Alcohol

Alcohol is a volatile fuel that we can’t store.  So, your body works hard to use it first.   

Protein

Most of us do not overeat protein because it is so satiatingProtein is the most challenging macronutrient for our bodies to convert into ATP, so it is a poor energy source for everyday use. 

Your appetite for high-protein foods also shuts down once you’ve had enough.

This leaves us with our two remaining major fuel sources: carbs and fat

Carbohydrates and fat

While your body likes to maintain some glucose in your bloodstream, you won’t burn the fat in your blood if you have too much glucose floating around. 

A little dietary carbohydrate can quickly raise your blood sugar levels because you can only store about 5 g of glucose in your blood (about a teaspoon’s worth). 

While we can convert dietary sugar into body fat through a process known as de-novo- lipogenesis, it’s usually dietary fat that is stored as body fat, because our body prioritises burning glucose first and fat last.  Thus, dietary fat that is not immediately burned off is easily stored. 

It’s not necessarily that fat is a better fuel source than carbs, but rather that glucose will show up in your bloodstream and register on your blood glucose meter after you eat.  Glucose essentially ‘floats on top’ of the fat in your bloodstream and adipose tissue

But it’s critical to note that the rise in blood glucose is also influenced by the fat in your diet and the fat stored in your body.  If your fat stores are already full, additional carbohydrates will affect your blood glucose much more.  Achieving healthy blood sugars is not simply a matter of avoiding carbohydrates.  Instead, you need to reduce the total amount of energy stored in your body so the glucose doesn’t back up into your blood. 

While we always burn a mixture of available fuels, the body prioritises the oxidation of the more volatile ones first.  So, to access your body fat, you must deplete any excess glucose and fat in your blood first. 

Your Body’s Fuel Tanks  

In your body, your fuel tanks for glucose and fat are separate but somewhat interconnected. 

As you deplete your blood glucose, the glycogen in your liver will be used to refill it (note: glycogen is the fancy name for the storage form of glucose).  

Only once you start to draw down glycogen stores in your liver your body will turn to the fat in your blood before moving on to using your body fat for energy.  

You can think of your available fuels like Jenga blocks stacked on top of one another, as shown below.  When you measure blood glucose, you are not just measuring the sugar in your blood.  Instead, you measure all the fuels cumulatively stacked up in your body.  

blood sugar
glycogen in liver and muscle
free fatty acids in your blood
body fat

If you want to nerd out a little more, the following table shows more detail in terms of:

  • oxidative priority,
  • approximate capacity to store the various fuels, and
  • their thermic effect. 
AlcoholKetonesExcess ProteinGlucoseFatty AcidsBody Fat
Priority123456
UseEnergyEnergyEnergy & ExcretionEnergyEnergyStorage
Capacity (calories)20201200 – 200015040,000 – 500,000
Thermic effect15%3%20 – 35%5 – 15%3 – 15%3 – 15%

How Your Body Uses Available Fuels

Oxidative priority helps you understand how the different fuels you’re consuming are used and stored.  Before we dive into how you can measure and manage your various fuel tanks, let’s quickly look at how your body uses the food you eat. 

Alcohol and Ketones

You have limited capacity to store alcohol or ketones in your blood. 

Because they are more volatile than the other fuels, they are the highest priority to be used.  Interestingly, alcoholics tend to have very low HbA1Cs.  This oddity is explained by oxidative priority.  They must use alcohol before metabolising glucose, so your body holds back the glucose in storage in your liver until the alcohol is cleared from your blood. 

Note: Ketones are usually only available when glucose and other fuels are very low, so this is not an issue.  But if you are using exogenous ketones, keep in mind that they are just another fuel that needs to be used before glucose and fat. 

Protein

Most of the protein you eat is used for muscle protein synthesis (MPS) and other critical bodily functions. 

While ‘excess protein’ not used in MPS can be converted to energy (ATP), this is a labour-intensive process that usually only happens when you’re not eating enough carbs or fat to supply your energy demand.  In this instance, your body turns to dietary protein and then the protein on your body (i.e. your muscles and organs) to provide itself with amino acids and energy.

Excess protein, or protein beyond what is required for muscle repair and other bodily functions, is metabolised by the liver as urea and excreted in the urine.  In other words, it is not used for energy.   

Protein has the highest thermic effect of any other macronutrient, meaning your body has to work hard to convert it to usable energy.  We expend between 20 to 35% of the energy we’re consuming when we turn it into usable fuel (ATP) and muscle.  

Thus, we don’t usually consume ‘excess protein’ and tend to gravitate energy from fat or carbs once we get enough protein.   

Glucose

Your body has some capacity to store glucose in the blood, liver, and muscle.  However, it’s not much compared to the amount of energy your body fat can hold!  If you don’t consume many carbohydrates, your body will work to convert protein to glucose (through gluconeogenesis) to keep your glycogen stores topped up, so you always have enough glucose available when required. 

Fatty Acids in the Blood

You have some fatty acids in your bloodstream to use for fuel.  However, this capacity is limited compared to the space you have to store excess energy you do not use. 

Body Fat

Because of genetics and other factors, some people can hold a tremendous amount of fat in their adipose tissue before it backs up and overflows into their bloodstream. 

Meanwhile, other people’s fat cells have a smaller capacity to store fat before energy overflows into their bloodstream, developing diabetes.  This difference in fat storage capacity is known as Your Personal Fat Threshold.

The bottom line is that you must deplete upstream fuels before your body uses any unwanted belly and bum fat.

What Does This Mean in Practice?

Imagine you’re at a BBQ, eating a burger with a beer and fries.  These magical food combinations taste terrific, and we can eat a LOT of them because they allow us to fill all our fuel tanks at once (i.e. alcohol, carbs, and fat with a dash of protein).   

This sort of meal would be perfect for a starving caveman or a marathon runner at the end of the event to quickly replenish depleted fuel stores.  However, if you didn’t need that much energy, your body will spend a lot of time burning off the energy from this meal.  First, the alcohol, followed by the carbs, and finally the fat. 

Your glucose and insulin will be elevated for many hours as your body works to metabolise and store the energy.   But if you eat again before you’ve used all of the energy, it’s primarily the fat that will be stored on your body for the long term. 

In addition, these magical fat+carb combo meals that tend to raise our blood sugar and insulin for a long time, also often result in blood glucose crashes that leave us feeling light-headed, hungry and highly motivated to eat anything and everything, well before we used up all the energy from our last meal.   

To put what we have learned about oxidative priority into practice, we can look at how a few popular ways of eating fill up your fuel tanks.

Scenario 1: A Modern Processed Diet

To unpack what oxidative priority means in practical terms, we have created some diagrams to help you visualise how you can unlock each fuel tank and burn body fat.   

The body has four main storage compartments for energy:

  • blood glucose,
  • liver and muscle glycogen,
  • fatty acids in the blood, and
  • body fat. 

The image below shows that these storage containers are separate but somewhat interconnected.

When it comes to oxidative priority, you can think of energy utilisation from left to right.  If one of the downstream storage containers becomes overfull, energy flows back upstream due to excess pressure in other fuel tanks.

This first fuel tank is the glucose in your blood.  Next, you have glucose in your liver and muscles, which is in its storage form, glycogen.  Once you use these up, you must burn the fat in your blood and liver before moving onto your body fat. 

These ‘tanks’ are separate but all connected by a ‘pipe’.  The pipe connecting each fuel tank to the next flows downstream and towards the right.  

Also, note that the pipe is not drawn to the bottom of each tank.  You needn’t exhaust or empty each tank to access the next fuel.  Instead, you must empty each one to normal healthy levels.

Unfortunately, we have optimised our modern diet to constantly top up every fuel tank at the same time.  Eventually, all the fuels in your body become backed up, preventing you from ever calling on your body fat for energy. 

Like the burger and fries with a beer on the side, when we eat hyper-palatable foods with a negligible nutrient density, we continue to fill our fat and glucose stores simultaneously.

Unfortunately, not only do these foods fill all our fuel tanks at the same time, but they also give us a double-dopamine hit, making it hard to put on the brakes once we start eating them.  

When these foods are readily available, we have no off switch for them, and our storage tanks become overfull.  Before long, we end up with energy toxicity, metabolic syndrome, diabetes, and other related conditions.

Scenario 2:  Low-Carb Diets & Fasting

The good news is that we can start draining our glucose stores when we reduce carbohydrates. 

But even if you go sans carbs, your body will refill your blood sugar from your liver glycogen stores, especially if you continue to overdo the dietary fat.  This is why your blood glucose drops to zero and might even continue to rise when you don’t eat.  

Your blood glucose is a small fuel tank that holds about 5 g or 20 calories worth of glucose.  Thus, it fills and empties quickly before and after meals.

You can get a precise understanding of your current energy status by measuring your blood glucose with a glucometer.  Our blood glucose gives us an accurate sense of whether our downstream fuel tanks are also overfilled.

In Data-Driven Fasting, we simply measure blood glucose before meals.  This trains people to wait until their blood sugar drops below their personal blood sugar trigger point, so they can drain their glucose stores before they eat again.

Waiting until blood glucose drops stops people from overfilling their upstream fuel tanks.  This, in turn, causes the body to use liver and muscle glycogen to refill blood glucose and deplete fatty acids in the blood, which are replenished from body fat stores.  After you’ve given it a bit of time, voila!  You’ll have lost body fat.

Some people run into trouble when they refeed with very high-fat foods.  High-fat foods provide a low satiety value across the board, and fat is the most energy-dense macronutrient.  This means that we tend to consume more calories when a high percentage of our energy comes from fat.

A keto or high-fat diet itself does not necessarily burn calories unless you’re also in an energy deficit.  Per the First Law of Thermodynamics, energy cannot be created nor destroyed, and calories are still calories.  Thus, if we eat a ton of high-fat foods and are not conscious of calories, our blood’s fat fuel tank is always topped up from dietary fat.  Hence, there is little opportunity for body fat to flow back into the bloodstream and be used for fuel. 

The idea that fat is a ‘free fuel’ because it doesn’t raise insulin over the short term is a mistaken belief.  We have seen this in many Data-Driven Fasting participants who have very low and stable blood sugars but still carry a lot of body fat.  So while their blood sugars are low, they continue to refill their fat tank, which keeps them energy toxic!

For more on this, check out Keto Lie #8: Insulin Toxicity is Enemy #1.

When people get stuck at this point, we recommend they focus on increasing the percentage of protein in their diet (i.e., by reducing both dietary carbs and fat).  This improves satiety and drains both their glucose and fat fuel tanks.  We’ll discuss this more in Scenario 5, but first, let’s touch on the low-fat, high-carb scenario. 

Scenario 3: Low-Fat, High-Carb Diet

In the high-carb, low-fat scenario, someone will deplete their blood fats despite continually filling their blood glucose and glycogen stores, as long as they are not eating a significant amount of fat.  Hence, stored body fat will flow back into their bloodstream to be used for fuel. 

While a low-fat diet can definitely lead to weight loss, the reality is that very few people can sustain a diet with low enough fat to drive fat loss over the long term unless they adhere to an ultra-strict whole food plant-based diet.   

As the chart below from our satiety analysis shows, very few people manage to maintain a very high-carb, low-fat diet.  Instead, they gravitate back towards foods that mix carbs and fat, which allow them to consume more calories as they fill all of their fuel tanks simultaneously. 

When it comes to fuelling weight loss, low-fat and low-carb diets restrict different macronutrients, but their effects are similar.  When consuming fat-and-carb combo foods that fill up your fat and glucose fuel tanks simultaneously, the body can quickly become overwhelmed with too much energy.  Thus, we only fill one fuel tank when we minimise or eliminate one of these energy sources.

It’s interesting to note that, as shown in the chart below from our satiety analysis, we tend to achieve a similar reduction in overall calorie intake by reducing either carbs or fat. 

The following heat map chart from our satiety analysis of data from Optimisers shows the relationships between non-fibre carbs, fat and calories.  The blue areas in the bottom left corner represent the lowest calorie intakes, while the red areas represent the highest. 

From this, we can see clearly that people who are able to eat the least tend to get a higher percentage of their energy from protein and less energy from fat and/or carbs. 

This brings us to our final scenario.

Scenario 4: Adequate Protein, Lower Carb & Lower Fat

In our final scenario, we have a nutrient-dense diet lower in both fat and carbohydrates that provides adequate protein. 

When we eat, sufficient protein and nutrients are what we truly require.  Carbs and fat are simply fuel sources that we don’t need as much of if we have plenty of energy in our systems as unwanted body fat or glucose in our liver and blood. 

Once we dial back both dietary fat and dietary carbs, we can deplete the carb and fat fuel tanks in our body so our body fat can flow back into our bloodstream to be used. 

Foods with a greater nutrient density and a higher protein percentage, or percentage of total calories from protein, tend to be hard to overeat.  Nutrients from low-energy, nutrient-dense carbs that are fibrous also tend to fill us up.  With time, body fat can flow back into the bloodstream from storage.

In the carb vs fat heat map below, the red areas align with the highest nutrient density.  Notice how they also tend to align with the lowest calorie intake?  When you give your body the nutrients it requires and dial back the energy from carbs and fat, your body is much happier to get on with using the excess glucose and fat stored on your body. 

How Do You Know What Your Ideal Diet Is?

While you don’t have to jump into a super high protein extreme, gradually ratcheting back easily-accessible energy from carbs and fat while getting adequate protein and nutrients is THE secret to fat loss

For more on why we don’t recommend you jump quickly to a super high protein % diet, see Secrets of the Nutrient-Dense Protein Sparing Modified Fast.

In our four-week Macros Masterclass, we walk Optimisers through dialling up their protein and fibre while scaling back their fat and carbs to find the balance that makes them feel their best.

The chart below is taken from our satiety analysis of our Optimiser data.  As you can see, the average protein intake of around 15% of calories tends to align with the lowest satiety outcome and most significant energy intake. 

If we can progressively reduce energy from carbs and fat and increase the percentage of our total calories from protein, we will optimise our satiation, consume fewer calories, and drain our carb and fat fuel tanks. 

Next Steps

  • To use your blood glucose to guide when you eat, to ensure you are progressively depleting the glucose in your blood to allow your body to use your stored body fat, you can check out our Data-Driven Fasting Challenge.
  • To understand your current diet and how you can progressively dial back energy from fat and/or carbs, you can check our Macros Masterclass
  • To jump straight into nutrient density to give your body everything it requires without excess energy, you can check out our Micros Masterclass.

Data-Driven Fasting Index 

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33 thoughts on “Oxidative Priority: The Key to Unlocking Your Body Fat Stores”

  1. Thank you so much for this article. Have 1.5 Diabetes and always wonder and sometimes get upset about why even if not eating or just drinking water glucose level goes up. Awesome explanations. Thamx

  2. The keto diet has been amazing for my blood sugar; not so for my cholesterol which is through the roof. And the only animal products I eat are eggs and dairy. Alas, with a 300 cholesterol, I will have to inch away from keto.

    • My wife of the last 40 decades have 330 and still alive after a few decades at that level, she is 73 and no medication. You may be one of so many unhealthy vegetarians than get here with the panic of unhealthy cholesterol. No idea what you eat all day and all your blood tests, it is up to you and a GOOD doctor.

    • Hi Sonia,

      Realise you left that comment some time ago but I think you probably don’t need to be too concerned. This video from an Australian conference on low carb eating may help to explain.

      https://youtu.be/TRB0jOfymLk

      The title is “High cholesterol on a ketogenic diet (plus do statins work) by Dr Paul Mason.

      You could just search for that if you don’t want to click on the link. He goes into detail about what cholesterol numbers really mean for people eating low carb and “standard” diets. It’s quite revelatory!

  3. I have tried a disciplined ketosis diet while checking everyday my body runs on ketone with Keto sticks and breath meter. So, I have factual evidence that my body feels and operates much much better while metabolising fats and zero carbs. I ate hard cheese eggs bacon dairy veggies beef pork chicken and sucralose in coffee. Society pushes crap food on people and its a compelling argument. Eat carbs and you will get immediate gratification. What type are you? That’s the conclusion. Read the original Atkins book. It is the closest thing to an operation manual for your body that I have found.

    • unfortunately, it’s hard to tell if high ketones are coming from your excess stored body fat or your diet. you need to decide if you want elevated ketone values as an end goal, or weight loss/metabolic health/diabetes reversal.

  4. I have been trying to lose weight and this article has made me understand why I haven’t been losing any more weight after my initial weight loos. Great article!!.

  5. This may be the cream on top of the coffee. But no matter what the diet / lifestyle / regimen, weight loss and good labs come down to Calories In vs. Calories Out and exercise.

    • yes. this just explains a little more about how the energy balance works. the fact that filling both the carb and fat fuel tanks at the same time drives overeating and is an underappreciated fact. there’s no magic, just better understanding.

  6. Another great article! This reflects my thinking, but you take it many steps further, to another level. This interconnected fuel tanks idea backing each other is great!

    Do not forget alcohol, please. 1litre of beer is 450 kcal or more, 0,5 litres of wine is 350kcal (but sugar next to nil). These amounts are easily consumed, and they are not only serious calories, but the metabolic side effects are substantial. Reminds me of an Italian study, where alcoholics were better in all metabolic values except liver alt’s etc. Best alc/€ over there is wine, red or white…

    I’d like to translate this to my native language…?
    JR

  7. I have followed the keto life-style for about 5 years and have maintained a 20 pound weight-loss by watching my carbs. Went from having three arteries balloon-angio’ed 5 years ago… to being declared perfectly heart-disease free on my last cardiologist visit, to his own amazement. I have also read countless articles explaining the glucose cycle as a pre-T2. NONE have explained the cycle from mouth to my body fat better than this. This should be required reading by all T2s…A million “thanks”.

    • Wow. Thanks Don! Glad it help understand who a low carb diet works (as well as how to troubleshoot a keto diet when it stops working).

  8. Thank you very much. A very unique article. I have never left a comment before, but the article is so wonderful that I could not depart without expressing gratitude.

  9. This is all fine and dandy but there is a problem with all of ‘it’. I spent 36 years in the medical profession and i can tell you that a person’s dietary habits that form in the early years of life are generally the same habits they take to the grave with them. Genetics, socioeconomic status, geographical location …. also play huge roles in determining how you grow into adulthood. Yes people will make mostly small to moderate changes (which are good) from time to time and along thew way and the very fortunate ones are able to continually improve upon those changes and ultimately be successful. But unfortunately we are as we were raised for the most part.
    But again even small or moderate changes can prove to be immensely helpful in preventing Diabetes, Metabolic syndrome, Hypertension, CAD and a plethora of other conditions.

    • Eating is definitely habitual and sometimes old habits die hard. In our Masterclass we see some people who can just follow the numbers and change how they eat overnight while some people struggle to make much change at all. Most people are somewhere in the middle. If the have useful guidance on what to eat that gives them results, a supportive community and a strong enough reason to change they can get there.

  10. How protein fits in seems murky. If I eat carbs, my body will stop burning fat right away, but what if I eat protein? How does the body determine what is ‘excess’?

    • your body is always burning a mixture of available fuels, but it will prioritise more carbs if they are available in excessive amounts. protein requirements depend on activity levels and lean body mass. your body craves adequate protein, but once it gets enough, your appetite for protein switches off, so most people aren’t getting ‘excess protein’ to the point they are using a lot of it for calories. it’s simply hard to convert to ATP, so your body loses interest.

  11. My triglycerides are 43 while my blood sugar is typically 100-115. Perhaps I missed it, but how does this fit into the oxidative priority model if blood glucose is the body’s priority fuel?

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