Richard D Feinman* and Eugene J Fine
Corresponding author: Richard D Feinman firstname.lastname@example.org
Nutrition Journal 2004, 3:9 doi:10.1186/1475-2891-3-9
(2004-10-06 14:36) Delta Research & Development, Bioengineer Research Center, affiliated to “Tor
In regard to the article “A calorie is a calorie violates the second law of
thermodynamics” by Feinman RD et al (Nutr J 2004; Jul 28;3:9 ), I believe it
is a useful brief thought on the proper application and interpretation of thermodynamics
We agree with several aspects of the article and with its overall meaning. However,
we believe there are still some potential conflicts regarding the analytical methods
to be used when a complex system such as the biological one is considered. This occurs
because we are forced to use a number of general laws and conceptually adjust them
to biology with its complexity and dynamics.
To examine energy transformations from a thermodynamic point of view, we adopt the
definition from physics of a calorie as the thermic energy needed to increase the
temperature from 14.5°C to 15.5°C of 1g of distilled water at 1 atm pressure,
even though the concepts are not wholly applicable to biology. In such a context,
the concept of a calorie used by nutritionists implies a somewhat arbitrary and "static"
equivalence which isn't suitable to thermodynamics. Briefly, since the thermic energy
cannot be directly utilized, the free energy of glucose (or other nutrients) does
not have a clear functional definition since it is practically impossible to foresee
whether and how such substrates will be transformed in work and heat, nor the efficiency
of their conversion which is understandably variable in a complex and dynamic system
such as the biological one (mainly due to the ever increasing entropy of the total
As an example, I believe that we might agree that the thermogenesis of an individual
exposed to low temperature (below the physiological one) has to be regarded as useful
work. Thus, heat production corresponds to an effective utilization of available energy
by contributing to homeostasis. However, the same thermogenesis occurring in an individual
exposed to a temperature higher than normal, forces the body to use the available
energy to produce work and recruits other physiological responses such as sweating
etc.). Since vital chemical reactions cannot be shut down. I believe that even in
considering apparently simple phenomena such as thermogenesis / thermoregulation,
we cannot ignore the complexity and properties of what is a dynamic system. Such properties
may change over a very short time, changing the related thermodynamics.
Since the complexity of biological systems is a primary factor and not secondary to
thermodynamic processes, we believe it isn’t possible to use a specific conceptual
analysis to clarify the relationship between calorie and body weight, beyond “conceptually-guided”
probability calculations [1, 2].
G. Marineo, F. Marotta
Delta Research & Development, Bioengineer Research Center, affiliated to “Tor
Vergata” University, Rome.
Via di Mezzocammino 85
00127, Rome, Italy
1. Marineo G, Marotta F, Sisti G (2004). Cirrhosis progression as a model of
accelerated senescence: affecting the biological aging clock by a breakthrough biophysical
methodology. Ann. NY Acad. Sci. 1019: 572-576.
2. Marineo, G. Marotta, F.. Biophysics of aging and therapeutic interventions
by entropy-variation systems. BioGerontology 2004 (in press)
Qualifications and Titles:
Researcher, Bioengineer (MD, PhD)
Convention with "Tor Vergata" University of Rome
-Basic research on developing theoretical biophysical models for medical use.
-Research and Development phase aimed at the treatment of chronic degenerative diseases
(Delta-S Entropy Variation System) and of untreatable neuropathic and oncological
pain (Scrambler Therapy).
- Founder and manager of Delta Research & Development, Medical Bioengineering
Research Centre with special convention with 'Tor Vergata' University of Rome.
BioMed Central Ltd unless otherwise stated. Part of Springer Science+Business Media.