Abstract
We apply the τ framework (τ ≡ E/c³ ≡ m/c) to human metabolism. Oxidation of macronutrients converts bodily mass into CO₂ and H₂O while releasing energy as work and heat. Expressed in τ units, breathing is a τ-exchange with the environment. We provide balanced reactions, mass/energy accounting, and practical, quantitative tests (indirect calorimetry, CO₂ mass capture, isotopic methods) to validate the τ interpretation in vivo.
1. Introduction
“Weight loss” is often discussed energetically, yet mass conservation reveals that most lost mass exits as exhaled CO₂ and H₂O. In parallel, energy is dissipated as heat and exported via biochemical work. In a τ-first view, where m = cτ, E = c³τ, metabolic processes move τ between body and environment through gases and photons, yielding testable relations between gas exchange, heat production, and body-mass change.
2. Metabolic Stoichiometry & Mass Balance
Representative fat oxidation (average triacylglycerol):
Mass balance (per mole of C₅₅H₁₀₄O₆ ≈ 861.4 g): O₂ consumed ≈ 78×32 = 2496 g; products: CO₂ ≈ 55×44.01 = 2420.6 g, H₂O ≈ 52×18.015 = 936.8 g. Total reactants ≈ 861.4 + 2496 ≈ 3357.4 g = total products ≈ 3357.4 g.
Thus, most mass leaves as CO₂ (gas) and H₂O (vapor/liquid), while the energy of oxidation is exported as heat/work.
3. τ-Formulation for Metabolism
Define τ as the “temporal charge” carried by matter/energy:
A breath exchanges Δm_air with the environment, hence Δτ_air = Δm_air/c. Summed over time, net mass loss Δm_body = −(m_CO₂ + m_H₂O + other excreta) corresponds to Δτ_body = Δm_body/c.
Gas-exchange observables (VO₂, VCO₂) thus provide direct τ-flux estimates.
4. Energy & Entropy Accounting
With respiratory quotient RQ = VCO₂ / VO₂, substrate mix is inferred (fat ≈ 0.7, carbs ≈ 1.0). Energy expenditure (EE) by indirect calorimetry can be estimated (Weir-type):
Because E = c³τ, measured EE maps to a τ-rate: \dot τ_E = EE / c³, while gas mass flow maps to \dot τ_m = \dot m / c. A consistent account requires \dot τ_E ≈ \dot τ_m after storage and mechanical work are included.
5. Quantitative Benchmarks & Examples
5.1 Per-breath CO₂ mass (at rest)
If VCO₂ ≈ 200 mL·min⁻¹ and respiratory rate ≈ 12 min⁻¹, then per breath ≈ 16–20 mL CO₂. At 1 atm, 37 °C, that is roughly 30–40 mg CO₂ per breath (order-of-magnitude), i.e., a per-breath τ export of ≈ (3–4)×10⁻⁵ kg / c.
5.2 “10 kg fat” oxidation example
Using the stoichiometry above, metabolizing 10 000 g of C₅₅H₁₀₄O₆ (~11.6 mol) consumes ~29 kg O₂ and produces ~28 kg CO₂ and ~11 kg H₂O. In τ units:
6. Implications
- Mass loss is directly measurable via gas exchange; τ renders this as a conserved flow between body and environment.
- Proper accounting must include oxygen mass in, not only CO₂/H₂O mass out.
- Calorimetry (energy) and spirometry (mass) provide two projections of the same τ-exchange.
7. Conclusion
Breathing is a τ-transport process: oxidation converts stored τ (mass/energy) into gaseous τ (CO₂/H₂O) and thermal τ (heat). This yields concrete, testable relations linking VO₂/VCO₂, heat, and body-mass change—placing everyday physiology within the same τ-first substrate as fundamental physics.
References
- Standard biochemistry texts on oxidative metabolism and respiratory quotient (RQ).
- Indirect calorimetry (Weir-type) formulations for estimating energy expenditure from VO₂ and VCO₂.
- Stoichiometric balances for fatty-acid oxidation (e.g., palmitate analogies) and average TAG models.
Appendix A — τ-First Biological Dictionary
A.1 Core definitions
A.2 Gas exchange & fluxes
A.3 Energy link
A.4 Example stoichiometry
A.5 Operational identities
Appendix B — Test Protocols (Checklist)
B.1 Lab Protocols (Human)
| Test | Observable | Procedure | Outcome |
|---|---|---|---|
| Indirect calorimetry | VO₂, VCO₂ (L·min⁻¹) | Metabolic cart; steady-state measures (rest/exercise) | Compute EE; infer τ-rate \dot τ_E; compare to mass flux \dot τ_m |
| CO₂ capture & weighing | ṁ_CO₂ (g·h⁻¹) | Soda-lime or molecular sieve; gravimetric difference | Quantify mass-out via CO₂; cross-check with VCO₂ |
| Humidity & water loss | ṁ_H₂O (g·h⁻¹) | Hygrometry of inspired/expired air; body weight change | Account for H₂O fraction of mass-out |
| Doubly labeled water | CO₂ production (mol·day⁻¹) | ^2H/^18O isotopic washout (free-living) | Integrate to long-term τ-flux; compare with weight change |
| Direct calorimetry (optional) | Heat Q (kJ) | Calorimeter chamber or high-precision thermal sensors | Energy-out check vs EE; τ consistency |
B.2 Analysis & Reporting
- Report mass-in (O₂) and mass-out (CO₂, H₂O) explicitly.
- Convert to τ via
τ = m/candτ = E/c³; verify τ-consistency across energy and mass channels. - State conditions (temp, pressure, BTPS/STPD corrections) and uncertainty.
- Include a one-line balance:
Δτ_body + Δτ_env ≈ 0(within measurement error).
B.3 Worked Example Template
Predict: Δm_body(T) ≈ −(m_CO₂ + m_H₂O + ...), ΔE_body(T) ≈ −EE(T).
Check: Δm_body/c ≈ EE(T)/c³.