The Fatal Flaw in the CICO theory: Oxidative Priority

How Oxidative Priority Dictates Fat Storage – Not CICO

As an anti-aging expert and founder of X Gym, I’ve seen countless people frustrated by the mainstream advice that reducing body fat is a simple equation of “Calories In, Calories Out” (CICO). This oversimplified model—the idea that a calorie is just a calorie and weight loss is purely a matter of energy deficit—is fundamentally flawed. It fails to account for the dynamic, non-linear reality of human metabolism.

New research, specifically the paper on Oxidative Priority, Meal Frequency, and the Energy Economy of Food and Activity, provides the physiological explanation for why CICO fails and, crucially, how we truly regulate fat accumulation. The body is not a bomb calorimeter; it is a complex, regulated system with a specific fuel hierarchy.

Fuel Partitioning and the Respiratory Quotient

The core mechanism CICO ignores is fuel partitioning, or how the body decides which ingested or stored fuel (fat, carbohydrate, protein) to utilize at any given moment. This process is quantitatively tracked by the Respiratory Quotient (RQ), the ratio of $\text{CO}_2$ produced to $\text{O}_2$ consumed. The Respiratory Quotient (RQ) is a number that reveals whether your body is primarily burning fat (low number, $\sim 0.70$ ) or carbohydrates (high number, $\sim 1.0$ ) for energy at any given moment. It sounds like a breathing rate thing, but it’s actually a cellular rate thing.

Low RQ ( $\sim 0.70$ ): High dependence on fat oxidation.
High RQ ( $\sim 1.0$ ): High dependence on carbohydrate oxidation.

The research paper demonstrates that focusing only on total energy expenditure (EE) is misleading. An individual can significantly increase their EE through exercise, but if that activity simultaneously raises the RQ, it shifts fuel use away from stored fat. This creates a seemingly paradoxical scenario in which an increase in total energy burned may result in minimal net fat loss compared to calorie restriction alone, because the percentage of fat utilized decreases.

The key takeaway is that the amount of fat utilized is more relevant than total calories burned. The simple CICO model, which uses an averaged 24-hour metabolic rate, completely obscures these critical, instantaneous shifts in RQ.

The Oxidative Priority Hierarchy

The research confirms that our bodies utilize and dispose of macronutrients according to a strict Oxidative Priority. This hierarchy is dictated by the storage capacity for each fuel source: those with limited or no storage capacity must be oxidized or converted first, thereby suppressing the oxidation of stored body fat.

Alcohol: No storage capacity. Highest priority for oxidation.
Protein: Limited functional storage (amino acid pool). Excess must be rapidly oxidized or converted (causing high Dietary-Induced Thermogenesis, DIT). Protein as the highest DIT, typically ranging from $20\%$ to $30\%$ of its total ingested caloric content. This high cost is due to the complex processes required to break down peptide bonds, and, more importantly, the high energy cost of deamination (removing nitrogen from excess amino acids) and converting the resulting carbon skeletons into glucose or fatty acids if they are not used for structural purposes.
Carbohydrates: Stored as glycogen (limited capacity). Once glycogen stores are repleted, oxidation is prioritized to normalize blood glucose, raising the RQ. Carbohydrates (CHO): DIT is typically lower, ranging from $5\%$ to $10\%$ of ingested calories. The process of converting carbohydrates to glucose and storing excess as glycogen is less energy-intensive than processing protein.
Fat: Unlimited storage capacity as adipose tissue. Lowest priority for oxidation. Fats (Lipids): DIT is the lowest, ranging from $0\%$ to $3\%$ of ingested calories. Dietary fat is easily packaged and stored in adipose tissue, requiring minimal energy for conversion or oxidation.

This hierarchy means that consuming high-priority fuels (alcohol, carbohydrates, and even excess protein) acts as a metabolic gatekeeper. When these fuels flood the system, their rapid disposal takes precedence, effectively sparing dietary fat and stored body fat from being burned. The fat you ingest, as the lowest-priority fuel, is efficiently shunted toward storage.

The X Gym Advantage: Optimizing RQ with Systemic Shock

This principle of optimizing fat oxidation by minimizing the high-RQ state and maximizing the fat-favoring state is the foundation of the X Gym methodology.

X Gym’s Biohack: Our unique, high-intensity functional training—which uses TUT to reach Complete Muscle Fatigue (CMF) in a short, 21-minute workout—burns only about 2 $100 \text{ kcal}$ during the session. However, the intensity creates a deep, profound systemic shock that triggers an acute, sustained metabolic disturbance. This necessitates a massive, prolonged recovery effort (EPOC), of at least four hours, which is powered primarily by stored body fat.
Traditional Training Flaw: A typical one-hour, lower-intensity training session burns a higher number of calories during the session (about 300) because of its longer duration. However, because it lacks the intensity, fatigue, and time under tension (TUT) necessary to cause significant systemic debt, its “afterburn effect” (EPOC) is minimal—often a simple $1:1$ ratio, resulting in a total post-exercise benefit of only about one hour. This limits the total time spent in an elevated, fat-oxidizing state to approximately two hours.
The Superior Result: The X Gym workout yields an afterburn effect of four or more hours of elevated, fat-burning metabolism. This means the X Gym method achieves a net fat-burning period of (at least) $4 \text{ hours and } 21 \text{ minutes}$ , far exceeding the two hours (max) of traditional training. We effectively use a brief, maximal effort to leverage oxidative priority and force the body into a sustained, low-RQ state of post-exercise fat disposal.

The Food Triangle and the Maladaptive “Chronically Fed State”

In our modern environment of unnatural calorie abundance and frequent feeding (the idea that “nutrition is an emergency”), most people live in a chronically fed state.

By snacking or eating frequently throughout the day, the body remains in the postprandial/absorptive state.
In this state, metabolism is primarily dedicated to the disposal of newly ingested fuel according to the oxidative priority (e.g., oxidizing glucose, converting excess protein).
During the postprandial period, the utilization of stored body fat is actively suppressed.

The energy balance that CICO suggests should lead to weight loss only holds if the body enters the fasted state—the only time where it is obligated to utilize energy reserves. By disrupting the fasted state with a constant influx of food, we unintentionally ensure that the body prioritizes storing the lowest-priority fuel: fat.

To move beyond the flawed CICO model, the researchers propose the Food Triangle, which organizes whole foods based on increasing energy density. Obviously, much more work needs to be done to fix our food system and dietary recommendations, especially in the USA.

Simplified Recap:

In case your head is spinning a little from these technical details, here’s a simpler explanation. Oxidative Priority is the body’s mandatory hierarchy for deciding which fuel to burn first. Think of it as a metabolic queue where the body prioritizes dealing with the fuel it cannot easily store.

Highest Priority (Must Burn First): Alcohol, then Carbohydrates, then excess Protein.
- The body has limited or zero storage capacity for these. It must oxidize or convert them immediately to maintain safe blood levels.
- Action: When these are present, the body switches to a high-RQ state to dispose of them, which acts like a “Pause” button for fat burning.
Lowest Priority (Store First): Dietary Fat.
- The body has virtually unlimited storage capacity for fat (adipose tissue).
- Action: When the body is busy burning high-priority fuels, the ingested dietary fat is simply packaged up and stored for “later.” Since the body is often in a “fed state,” that “later” (the fasted, fat-burning state) never arrives, leading to accumulation.

In the simplest terms, The more fuel you eat that isn’t fat, the more you force your body to store the fat that you do eat. Maximizing fat loss requires you to eliminate these high-priority, fat-sparing fuels to force your metabolism into the low-RQ, fat-burning state.

A Scenario Example:

If person A is eating lots of carbs, drinking alcohol, and not prioritizing protein, they will be a fat-storing machine.

If, on the other hand, person B is eating high protein, low carbs, and no alcohol, they will be a fat-burning machine, even if the calories are equal between the two people.

Let’s analyze these two scenarios based on the Oxidative Priority hierarchy, assuming calories consumed are the SAME between the two scenarios:

Scenario 1: High Carbs, Alcohol, Low Protein = Faster Fat Gain (and slow to no fat burn with exercise)

This person is consuming the two highest-priority, fat-sparing fuels: Alcohol ( $\text{RQ} \sim 0.67$ ) and Carbohydrates ( $\text{RQ} \sim 1.0$ ).

Immediate Fat Suppression: Alcohol has the highest oxidative priority, meaning it is burned first, immediately and severely suppressing fat oxidation (the paper notes alcohol can suppress fat oxidation by up to $87\%$ ).
Sustained Fat Suppression: The high intake of carbohydrates forces the RQ up towards 1.0. The body must prioritize oxidizing this glucose to maintain stable blood sugar and replenish glycogen.
Low Protein, Low DIT: The low protein intake means the body experiences a low Dietary-Induced Thermogenesis (DIT). This person wastes very few calories on the digestion and conversion of excess protein.
Result: Due to the combined effects of alcohol and carbohydrate oxidation, the majority of the dietary fat consumed (even if it’s a small percentage of total calories) is spared from oxidation and rapidly stored. The total $\text{Fat Oxidized}$ over 24 hours will be the lowest, leading to the largest $\text{Net Fat Accumulation}$ .

Scenario 2: High Protein, Lower Carbs, No Alcohol = Slower Fat Gain (and effective fat burn with exercise)

This person removes the two most potent fat-sparing fuels (alcohol and high carbs) and emphasizes the high-DIT macronutrient (protein).

High DIT (Calorie Waste): The high protein intake leads to a significant increase in DIT (burning $20\%$ to $30\%$ of the protein calories as waste heat). This effectively reduces the “Net Calories In” available for storage and is essential for processing the excess amino acids that cannot be stored.
Lower RQ: By restricting high-carb intake and removing alcohol, the body’s baseline RQ stays lower (closer to $\sim 0.85$ or less). This allows a higher percentage of the total energy expenditure to be sourced from fat oxidation throughout the day.
Fuel Utilization: The body has to burn the protein for the DIT cost, and the remaining energy needs are met by a mixed oxidation that favors fat more than in Scenario 1.
Result: This person burns more of the ingested calories as heat (DIT) and utilizes a higher proportion of fat throughout the day. Although both people consumed the same total calories, the $\text{Net Fat Accumulation}$ will be lower in this scenario because $\text{Fat Oxidized}$ is maximized.

In conclusion, a calorie is not isometabolic. The paper demonstrates that the source of the calories fundamentally changes the $\text{Fat Oxidized}$ term, confirming that metabolic outcomes are governed by the macronutrient composition, not just the total energy balance.

P.S. People who train at X Gym are much better fat burners than those who train at a traditional gyms, but when they eat how we advise, they burn fat and gain muscle at the same time (recomposition) faster than they ever imagined was possible.