The DOI matches its Crossref record; 22 of the 22 references it cites were found in a registry or an index.
"A calorie is a calorie" violates the second law of thermodynamics
Open accessAbstract
The principle of "a calorie is a calorie," that weight change in hypocaloric diets is independent of macronutrient composition, is widely held in the popular and technical literature, and is frequently justified by appeal to the laws of thermodynamics. We review here some aspects of thermodynamics that bear on weight loss and the effect of macronutrient composition. The focus is the so-called metabolic advantage in low-carbohydrate diets – greater weight loss compared to isocaloric diets of different composition. Two laws of thermodynamics are relevant to the systems considered in nutrition and, whereas the first law is a conservation (of energy) law, the second is a dissipation law: something (negative entropy) is lost and therefore balance is not to be expected in diet interventions. Here, we propose that a misunderstanding of the second law accounts for the controversy about the role of macronutrient effect on weight loss and we review some aspects of elementary thermodynamics. We use data in the literature to show that thermogenesis is sufficient to predict metabolic advantage. Whereas homeostasis ensures balance under many conditions, as a general principle, "a calorie is a calorie" violates the second law of thermodynamics.
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“Comparisons of isocaloric diets of different macronutrient composition frequently show no difference in effectiveness but there are several examples where distinct advantages accrue to one of the diets, usually the low carbohydrate arm [21-25].”
From The case for low carbohydrate diets in diabetes management (2005) · cites this paper as [23]
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Cites
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- Eades MR, Eades MD: Protein Power. 1996, New York, Bantam Books
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TAN, M. K., Öngel, M. E., Yılmaz, B., & Özilgen, M. (2025) · Elsevier eBooks · doi:10.1016/b978-0-44-313219-3.00173-8
Reilly, R. R. (2026) · Strength and conditioning journal · doi:10.1519/ssc.0000000000000964
Common questions and misconceptions about diets: what does the scientific evidence really show?
António, J., Antonio, B. B., Aragon, A. A., Arent, S. M., Campbell, B. I., Candow, D. G., Eberhardt, H. K., Escalante, G., Evans, C., Forbes, S. C., et al. (2026) · Journal of the International Society of Sports Nutrition · doi:10.1080/15502783.2026.2707252
Metadata
- Authors
- Feinman, R. D., & Fine, E. J.
- Affiliations
- State University of New York (US)
- Corresponding author
- Feinman, Richard D
- Venue
- Nutrition Journal
- Published
- 2004-07-28
- Volume
- 3
- Issue
- 1
- Pages
- 9-9
- ISSN
- 1475-2891 (ISSN-L)
- PMC
- PMC506782
- OpenAlex
- W2129810037
- Cited by
- 104
- References
- 22
- Citations by year
- 2026: 2 · 2025: 3 · 2024: 3 · 2023: 1 · 2022: 6 · 2021: 3 · 2020: 11 · 2019: 2 · 2018: 6 · 2017: 7 · 2016: 5 · 2015: 1 · 2014: 8 · 2013: 5 · 2012: 5
- FWCI
- 3.92
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- Nutrition Journal (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Topics
- Health Sciences › Medicine › Physiology (medical) › Diet and metabolism studies
- Health Sciences › Medicine › Physiology (medical) › Dietary Effects on Health
- Life Sciences › Neuroscience › Endocrine and Autonomic Systems › Regulation of Appetite and Obesity
- Keywords
- second law of thermodynamics, macronutrient composition, weight loss, hypocaloric diet, low-carbohydrate diet, thermogenesis, homeostasis, energy balance
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