The metaphorical ‘metabolic flexibility’
My crazy moments are when I drive around the Los Angeles. I am almost subconscious and cozy about everything, gritting my teeth and stiffening my muscles. My mind wander about the delay caused by the traffic jam and how irate it causes my behavior to be. With my back pain becoming terrible, I endeavor to alleviate it by all means; I shift backward and frontward to make the pain disappear. And this urge to pee gets my nerve piled up with tension to knock the front vehicle out of the way. I squirm within my seat uncomfortably and the distance is still counting. It has just been a mile coverage within the 15 minute drive, and guess what? The traffic jam is crazily tight – no room to run aside for special peeing moment.

About forty-five minutes later, I’m away from the jam fracas and straightly heading for the North Carolina. The miraculous opening of the highway lets me travel by utmost speed to reach my destination. I welcome back my relaxed position and let out my sigh of relief. Now I feel my back getting fine but with peeing, it was like I had imagined it or maybe I let it down to my pants. Being not in a puddle, I needed a damn relaxation.
A timeline of two weeks later and I am in North Carolina, Asheville town. Like the other big towns, Asheville is light everywhere as traffic soars along the busy roads. This is my routine round the year; Santa Monica three months, and Asheville another three months.
I call this story a perfect metaphor of the “Metabolic flexibility”.

What is the gist of metabolic flexibility? The two main fuels that your body burn are carbs and fats, in their simplest forms, glucose and fatty acids. Additionally, your body can burn protein and ketones, but they are not the major fuel for the body.
Protein as a fuel is identified as an expensive fuel because a lot of energy is used to burn it. More so, it is likely inconvenient for the energy producing processes but likely better for moving and lifting body contents (as plasma) from one place to another. As for ketones, it is only contingent for burning when trimming out body fats.
Alcohol is also very connected to this list. With 7 calories per gram of energy, alcohol is known to take much space in the metabolic machinery being a source of acetyl CoA. Acetyl CoA is the end product of the breakdown of sugar and fat. Alcohol probably inhibits/interferes with much of the breakdown of the fats and sugars by reaching the end point faster than the normal process. The entire metabolism process stop when it detects much acetyl CoA produced and this only ensures partial breakdown of the sugar and fats. This way, alcohol attributes to a less flexible or inflexible metabolism.
In relatively understandable example, alcohol can take a form of an 18 wheeler semi-truck as carbs and fats take forms of SUVs and Sedans consecutively. If sedans are left to move freely, most often you will experience SUVs and semi-trucks getting in the way to hinder the free movement. This is the same case with burning fats, your system should handle both sugar and alcohol with efficiency required.
While, protein has a complicated, inconvenient and costly process of breakdown. Being versatile, it has many entries of energy production apart from acetyl-CoA production. Let’s use this metaphor to describe its process: proteins are like a bird ride-share electric scooters, bicycles or motorcycles. They can easily overlap in and out of the traffic jam for convenience, but trouble is involved while they are caught up in the rains.
On the other side ketones may represent public transport because when they get ramped up and become efficient, they reduce congestion from the highway.
What is metabolic flexibility?
The ability to quickly switch on from one source of fuel to another depending on food source available and the demand of the fuel by the body is known as the metabolic flexibility. In terms of traffic, metabolic flexibility exhibits a wide-open highway with 20 blocks green light.
Also, take this direct example, an active teenager eating a large bowl of Cinnamon Toast Crunch in immediate morning and his metabolism becomes quite active to produce a sweat. Then during breakfast, he gets on eggs and bacon when metabolism is already on. Again, metabolic flexibility means being on football practice for 2.5 hours with a burnt egg for breakfast and an unpeeled grapefruit as a lunch meal. To handle all these fuel demands, your body needs a healthy and flexible metabolism.

What is metabolic inflexibility?
Compromised energy pathways of a metabolism signifies a metabolic inflexibility. For instance, having a parade, the Super Bowl, a semi-truck convention and massive construction on the i405 on a same weekend. A further example of an inflexible metabolism is a one that despite being well fed, he or she is still tired, irritated, fat and still hungry. It is a sort of an imbalance of energy inflow and energy outflow (metabolic gridlock).
If you want a performing metabolism, flexible metabolism is better because it is kind of a great multi-tasker. It can handle both burning of sugar and fats. But how do we get it?
Let’s first of take a look at the causes of the metabolic inflexibility to better understand metabolic flexibility and how we can get it. One cause of the metabolic inflexibility is the top-down approach of our dieting as below:
The Top-Down Approach
- High calorie loads or macronutrients are associated with hormonal effects
- Too much carbs effects to high insulin amounts
- Sugar and fats are likely to end up damaging the blood tissue or getting restored.
- Insulin resistance has a tendency of hindering sugar and fats from entering cells for burning.
- Insulin resistance is also likely to be effected by chronically high cortisol.
- A very high insulin stops further release of insulin and stops the body from any insulin-initiated response.
Opposite to the top-down approach, there is also a bottom-up approach. Below is the bottom-up approach postulates:
The Bottom-Up Approach
- Multiple and huge mixed meals with high energy amounts reaches the mitochondria all at once.
- As mitochondria works round the clock, it is reached by nutritional resources that falter about.
- Hydrogen peroxide and other free radicals in their high amounts damage the mitochondrial membranes, changing the DNA.
- Signaling molecules and depleted cofactors necessary for mitochondrial function slows down energy production.
- The damaged mitochondrial integrity, the excess energy precursors from fat, carb and alcohol and slowdown in the function of mitochondria will cause a backup of sugar and fats metabolites.
- Carbs burning gets blocked by Acetyl-CoA from excess breakdown of fats.
- Fats burning gets blocked by Acetyl-CoA from excess breakdown of sugar.
- Both fats and carbs get blocked by alcohol acetyl-CoA.
- Breakdown of cellular function begins.
- The function of insulin receptor is compromised.
- Insulin of the bottom-up ensues and it rises the blood sugar and blood fats.
- Then insulin resistance of the top-down presents.
This will turn you into a tired, fat, depressed, snoring and always anxious person.
Fuel Burning Process (4 Step Method)
The four steps of the fuel burning process include:
- Fuel released from the fat storage depots through lipolysis process. Lipolysis is the breakdown of fats through a metabolism process. Fuel from this storage is then released to the body.
- Release fuel and shuttle to the cells where they are needed. Flow of blood is very necessary here.
- Inserting into those cells the fuel. Insulin receptors are needed here.
- Fuel burning in the cell; in the mitochondria, the oxidation of fatty acid occurs where fats are being burned.
The defects of metabolic inflexibility occurs as top-down effect at step 3 and/or bottom-up effect at step 4. Science is working on which of the two effects is more important; a likely interconnection of environment and genetics.
One of the logics are with you which basically knows that eating too much may not necessarily impact to body weight gain. For instance, a 200-pound bodybuilder friend of mine can manage to consume 4000 calories but still is as lean as never, and another 225-pound recreational lifter gains much fat if he consumes more than 2500 calories.
Our ancestors had pretty good monitoring of diet as well as flexible metabolism is concerned. Take for example, as hunters and gatherers, available food for consumption was what was hunted and/or gathered from the field. If gathering was successful and hunting not, then they had consumed the only gathered and vice versa.
At the same time, they had eaten fewer calories as well as less sugar and fats. Macronutrient intake was a logic later embraced, not in the times of our ancestors but basically, fruits and tubers were the major sugar sources at certain seasons of the year. And because tools to harvest wheat and to bake wheat products were lacking or not discovered, fruits and tubers had become a main diet for their dailies. Add this fact for logics; wild animals might not be super fatty as fatty vegetables may not be frequent and around the season.
Further, the ancient people slept longer from the setting of the sun to the rising of the sun. They coupled it with lots of walking that gave them a lifestyle with flexible metabolism for survival. Being flexible metabolically may mean that some things we might do are very natural or have become natural as they were from our ancestors times.
There are four basic food approaches that can better aid metabolic flexibility. These are derived by putting into memory the five-factor conditions of metabolic inflexibility which are; sleep, hunger, mood, energy, and cravings. This is abbreviated as SHMEC.
Based on SHMEC conditions, a person is said to be metabolic inflexible and have a high need to regulate their diets on below interventions:
- Using Single Macronutrient Diets like Keto
After stabilizing metabolic flexibility to some extent, you can now concentrate on a single food type that you chose, but not two or many. Obviously, mitochondrial tend to be overwhelmed when more food types of more fuel types are taken, especially in large amounts.
In this case, the vegan and ketogenic diets prove to be great beneficial as far as insulin resistance is concerned (a metabolic effect). Two diets tend to complement greatly along efficiency of metabolic flexibility; diet of more fats and less carbs and a diet of more carbs and less fats. These diets reduce the multitasking tendency of the mitochondria and allow a uni-optimization on one pathway.
Most defining diet (Keto) is known to be of great benefit though some are quite hidden. For example, Keto is always associated with savory and creamy flavor – it is a ‘one-flavor-diet’. With single-flavor diet like of Keto, they tend to shut down hunger. What happens is that the feedback by the neural system in the brain will decrease hedonistic behavior of seeking food.
- Exercising and Cycling Diet
The fuel you are likely to burn when exercising is mostly correlated with that opposite fuel you burn when not in exercise. For example, you eat more fat and you burn more fat during your rest but when you burn fats during exercise, you tend to burn carbs during rest.
If you think about combining diets and apply exercise strategies, it is basically important to exercise while cycling your diet. A better fat burner is enhanced by an exercise that engages more sugar pathways to fuel the exercise with more sugar. With an exercise of high intensity, you may need to add up more carbs to deliver the required fuel for that time. This approach may be called ‘Eat More, Exercise More’ approach or EMEM.
But for fats, eat more and adopt a less intensity exercise. The fat-adapted athletes may need a very low carb Keto diets coupled with very less exercise such as walking. This approach is called ‘Eat Less, Exercise Less’ approach or ELEL.
There is also another approach known as ‘Eat More, Exercise Less’ or EMEL. This method ends overwhelming mitochondrial pathways from a bottom-up effect and top-down effect. While, ‘Eat Less, Exercise More’ or ELEM may result to radical changes such as compensatory eating and insulin resistance that is stress induced.
Metabolism flexibility can be best achieved at different metabolic toggles as indicated below;
- ELEL becomes a winter toggle
- EMEM becomes the late spring
- ELEM becomes the early spring toggle for a few weeks
- EMEL is a final late fall toggle that also takes a few weeks.
- Eating fiber and protein frequently
Mitochondria are bound to undergo a metabolic gridlock if fats and carbohydrates are introduced largely on to them. These individuals of metabolic inflexibility may not be able to effectively burn either sugar or fat. They also kind of fall victims of cravings, energy lows and hunger effects.
In a study titled ‘Fat and Carbohydrate Balances During Adaptation to a High Fat Diet’ published by the American Journal of Clinical Nutrition a chart produced had reflected that the higher the number the more carbs burned while the lower the number the more fats burned.
How does it work? Protein and fiber tend to clear mitochondrial highways compared to fats and sugar hence allows for repair. It is important to take small frequent meals of these types of diets to avoid binging on large foods of carbs and fats. This used to be an old approach of body building but also works effectively to those who are beginning to diet and to those who have a problem of large eating when they skip meals.
The frequent fiber and protein eating approach enhances more and better food interaction for individuals. It bases its teachings on levels of calories in foods, preparation of food and macronutrient content. Most individuals have been successful to trim their fats to be and stay fit through this method of dieting. It is a necessary part of fitness journey for many people, if not variety.
With a restored metabolic flexibility, you can try minimal fasting or single macronutrient intake (Keto) that requires less frequent eating. Remember the science that metabolic control and/or flexibility may be overwhelming with a three big meal per day approach. This approach may reintroduce a metabolic gridlock. While, smaller frequent meals is efficient enough to reduce the metabolic jams.
- Intermittent Fasting
Another method of stabilizing metabolic flexibility is by fasting. A better way to start fasting is by equally distributing the time you take eating and the time when you don’t eat. Let’s say, you substitute a twelve hour of eating with a twelve hour of not eating consecutively. Because most of the times when fasting occurs is when individuals are asleep, this method becomes very simple to practice. When one gains a flexible metabolism, fasting begins being easy and a person might go for a long time without eating. During adaptation one may try going on a longer fasting period, like between 16 to 24 hours.
The fastest way to restore metabolic flexibility and a very natural way, of course, is by fasting. However, caution is needed to those of inflexible metabolism because they are likely to fall victims of negative reactions induced by fasting. Fasting is not just a starting approach for most people because it might be a source of body and metabolic dysfunctions if not taken care of.
Metabolism as a Stress Barometer
Metabolism process is like a big stress barometer which senses and measures the amount of stress in the body and relays that info to the inside cells. Using the hormonal system, it regulates the mechanisms of metabolic inflexibilities by the top-down and bottom-up mechanisms. Mostly, metabolism control the activities of exercise, temperature rise and fall, sleep, movement and stress.
- Exercise: This works by creating a transient state of flexible metabolism.
- Temperature: Metabolic flexibility are always increased by temperature adjustment.
- Sleep: Sleeplessness influences the insulin resistance to worsen and impact to negative effects of stress.
- Movement: Non-vigorous movements such as walking has multiple bottom-up and top-down effects. This happens when these effects clear the fat-burning pathways, lowering the cortisol and increasing the glucose receptors.
- Stress: Stress involves hormones which catalyzes metabolism. These stress hormones are cortisol and adrenaline, and they are all concerned with liberating fuel.
Supplements to Restore Mitochondrial Flexibility
Mitochondria are little engines that take fuel in and burn it. A damaged mitochondria is like a beat-up jalopy that will continue to spew black smoke, and backfire as it sputters along. The black smoke is in jalopy form but its representation in mitochondria waste product, it is the hydrogen peroxide produced. It will eventually damage the cellular machinery and cause a constant irritability, very less energy and hunger. To enhance the effectiveness of the mitochondrial flexibility, the following supplements will up the game;
Glutathione (GSSH)
Glutathione neutralizes the radicals formed in the mitochondria which are like a hot sticky mess. To obtain glutathione, its best source is from whey protein. Whey protein is very rich in glutathione precursors besides being a glutathione well-established booster. Whey protein cushions free radicals to stabilize metabolism efficiency.
NAD+
This is both an energy precursor and a molecule signaling the mitochondria. It is very integral to energy production, acting as NADH precursor that shuttles electrons to parts of the mitochondria.
Alpha-lipoic-acid
Alpha-lipoic-acid is both fat-soluble and water-soluble antioxidant. It alleviates metabolic damage by the free radicals in the cell’s cytosol and inner membranes of the mitochondria where metabolism occurs. It also helps keep glutathione to last longer.
Acetyl-L-Carnitine
Acetyl group attachment on carnitine allows for shuttling of fats into the burning machinery of fats in the mitochondria. Carnitine is good in buffering the mitochondria against metabolic smoke produced by inflexible metabolism.
Real Life Metabolism Enhancer
If you want a flexible metabolism, then eat and train in different modules – change styles, habits, and frequency. Eat more carbs if you used to be fat-eater guy. The same applies to runners who basically relied on running as their sole exercise, let them do some weights too. Challenge your metabolism to train your metabolism. If you apply same methods all time, you of course remain the same. This is how Keto diets, fasting, refeeds and interval feeding works to challenge the body metabolism.