Ph.D. Thesis

By Preston Zen

Kcal Efficiency Quantization Model

A New Metric for Measuring Activity Performance in Kcal


The Task Efficiency Score introduced in this study provides a comprehensive way to quantify physical and mental energy costs of activities in kilocalories (kcal). Intended to optimize efficiency and well-being for individuals and organizations, this metric accounts for human energy expenditure more holistically than existing productivity indexes.



Efficient task completion is critical for personal well-being and organizational success. However, most existing metrics like time management assessments and productivity scores fail to fully capture the human energy expenditure involved. They particularly lack accounting for mental activities' energy costs.


This study aims to develop a quantifiable metric incorporating kcal costs, universal Freedom Factors, and considerations for physical and mental health. The resulting Task Efficiency Score can provide practical guidance for individuals, managers, and organizations.


Task Efficiency Score (TES)

TES = Physical Energy Consumption - (Freedom Factor kcal Consumption Rate) - Mental Energy Consumption

Freedom Factor

The Freedom Factor is a unitless measure from -1.0 to 1.0 representing the freedom experienced during a task, formulated as:

Freedom Factor = Control over task + Structure of task + Unpredictability of task + Creative input in task


 Level of autonomy, from fully prescribed (0) to fully self-directed (-1 to 1). 


Flexibility in how tasks are done, from rigid (0) to adaptable (-1 to 1).


Variability level, from completely predictable (0) to highly uncertain (-1 to 1). 


Ability to innovate, from rote (0) to purely generative (-1 to 1).

Physical Energy Consumption

Calculated via indirect calorimetry to determine kcal spent in physical exertion.

Mental Energy Consumption

Calculated through physiological markers like EEG, EKG, GSR, eye-tracking, and self-reported complexity rubric.


Physical Energy Measurements

Indirect calorimetry measures oxygen consumption and carbon dioxide production to quantify kcal expenditure.

Mental Energy Measurements

Complexity rubric combines time, problem-solving, expertise required, cognitive load, and physiological markers of EEG, EKG, GSR, eye-tracking to determine mental kcal costs.

Freedom Factor kcal Consumption Rate

This coefficient indicates the mental energy needed to overcome restrictions imposed by a task.

Results and Discussion

Task Sustainability Score

TSS = TES / (Available Physical Energy + Available Mental Energy)

This score guides long-term planning by indicating capacity to sustain task performance.

Professional Implications

The $ per kcal index is introduced to evaluate economic returns for job roles based on energy efficiency.

Adaptability Score

AS= kcal consumed in 1 second / FF in 1 second

Shows how quickly one adapts to a task, influencing the overall TES.


By integrating kcal as a universal measure of human energy expenditure and balancing physical and mental factors, the Task Efficiency Score provides a new paradigm for evaluating productivity. This human-centric approach has the potential to revolutionize efficiency across individuals and organizations.


Me + Pi + GPT-4 + Claude-2 + Bard + Ph.D. Mental model from Jeff Burke = This

Written with the motivating pretext of being Passionate, Hungry, and Determined ;)