EPK Research develops and publishes the Energy per Kilogram framework—an open, traceable approach to investigating energy availability in relation to body mass.
Research exposure: kcal/kg/day. Exercise expenditure and fat-free mass are measured separately; this is not the sports energy-availability equation.
The EPK Paper Series
Version 1.2 integrates the recent evidence on fuelling, adherence, stress, sleep, performance and tissue function, with corrected citation mapping and explicit research tests. Unverified MSc quantitative claims are excluded from the evidential basis. Earlier releases remain available below and on Zenodo.
Current paper PDFs are licensed under CC BY-ND 4.0: share credited copies; modified versions may not be distributed under this licence. This applies to author-owned text in these PDFs.
Introduces EPK through published research on appetite, adaptation, stress and dietary adherence, with wearable-informed targets and a staged plan for testing the framework.
Explores whether behavioural stability during dieting may itself be influenced by physiological energy availability and compensatory pressure.
Extends EPK beyond static calorie models to examine substrate competition, dietary-fat storage and metabolic flexibility.
Examines whether sports physiology can help explain fatigue, reduced movement and poor recovery in the general population.
Considers energy availability, compensatory physiology and functional decline outside athletic populations.
Sets out a cautious, testable neuroenergetic hypothesis linking energetic sufficiency, movement and metabolic flexibility.
Proposes that immune responsiveness may be shaped by both danger signals and the energetic resources available to respond and recover.
Further working papers
Narrative working papers on energy estimation, dietary composition, body composition and energy requirements. These supplements report no new experiments and are not peer reviewed. Each has a permanent Zenodo DOI.
A selected evidence review linking dietary composition, cortisol, PUFA, tissue regeneration and recovery to testable EPK questions. Includes 14 references, study limitations and connections to the seven working papers.
Zenodo DOI 10.5281/zenodo.23103192A nine-page review with 11 primary research references, examining restriction, stress responses and abdominal fat. Distinguishes visceral fat, subcutaneous fat and visible muscular definition, and considers sustainable body-composition goals.
Includes evidence of abdominal fat loss during restriction and a proposed study of EPK, function and dietary tolerability.
Zenodo DOI 10.5281/zenodo.23101380A review of individual energy estimation, low-fat diets and performance fuelling, with 22 references. Examines wearable data versus resting-expenditure × PAL estimates, prescribed and achieved fat intake, and the evidence for a 15% performance surplus.
Distinguishes evidence supporting the approach from questions requiring EPK validation.
Zenodo DOI 10.5281/zenodo.23097644Examines where 25 kcal/kg/day is used, distinguishes guidance from physiology, and proposes a clinical validation design.
Zenodo DOI 10.5281/zenodo.22712260Separates intake, expenditure and sports energy availability, then proposes a repeated-measures performance study.
Zenodo DOI 10.5281/zenodo.22712284Maps gestation, birth, growth, adulthood and clinical care while preserving population and measurement differences.
Zenodo DOI 10.5281/zenodo.22712302Research articles
Primary studies, their limits and the questions they raise for EPK. Browse all articles
Stress can alter cellular energy use while disrupting eating. Some people lose their appetite; others eat more or choose differently. What does that mean for adequate fuelling?
Read article Research perspective · 20 October 2026Protein solubility offers a useful extension to the energy-currency explanation of ATP, without replacing its established energetic role.
Read article Research perspective · 20 October 2026Water–protein interactions matter. Their existence does not establish that most cellular water is immobilised or that a particular diet restructures it.
Read article Research perspective · 20 October 2026Artificial membranes are not living cells. A critical examination of what reconstruction can demonstrate, what it leaves out, and how to assess Ling’s alternative.
Read article Research perspective · 20 October 2026Reconstitution, molecular rotation and competing explanations: examining the evidence behind energy coupling.
Read article Research perspective · 20 October 2026Overfeeding experiments show an adaptable expenditure response—and the limits of that adaptation.
Read article Research perspective · 20 October 2026Higher resting expenditure can accompany greater oxidative capacity—or fever, catecholamine activity and tissue loss. The cause matters.
Read article Research perspective · 20 October 2026Muscle energy markers and force can recover on different timelines. Adequate fuelling matters, but it is not the only part of recovery.
Read article Research perspective · 20 October 2026A genetic rescue experiment raises an important mineral-regulation question, but does not establish a universal low-phosphate diet.
Read article Research perspective · 20 October 2026Why useful fuel, persistent accumulation and a sporting test result need different interpretations—and why fuelling matters more than chasing a low lactate number.
Read article Research perspective · 19 October 2026Knowing what comes next and having a meaningful choice are different forms of support.
Read article Research perspective · 19 October 2026Dietary rules can create a second problem after the meal: abandoning the plan or trying to compensate for it.
Read article Research perspective · 19 October 2026Leaving work and recovering from its demands are not always the same event.
Read article Research perspective · 19 October 2026Knowing what you want to do and being able to act on it under pressure are different problems.
Read article Research perspective · 19 October 2026Appetite is an outcome worth measuring, not an inconvenience to remove from the story.
Read article Research perspective · 19 October 2026A useful record should help someone understand their needs without making every meal a test.
Read article Research perspective · 19 October 2026Mental fatigue can change performance without demonstrating a large extra calorie expenditure.
Read article Research perspective · 19 October 2026Performance reflects the task and the setting as well as what someone knows how to do.
Read article Research perspective · 19 October 2026Information accuracy, comfort and connection are different outcomes—and all deserve attention.
Read article Research perspective · 19 October 2026Why reassurance, memory and returning to activity do not always move at the same pace.
Read article Research perspective · 19 October 2026Taking dietary distress seriously also means examining trials in which participants reported benefits.
Read article Research perspective · 17 October 2026A grip-strength study raises a useful question for nutrition research: what happens to the person’s capabilities, alongside their body mass?
Read article Research perspective · 17 October 2026A cellular-ageing study connects mitochondrial signals with membrane fats—and complicates the idea that more energy production is always better.
Read article Research perspective · 17 October 2026The demands of a long race reach beyond the calorie counter. What can red-cell research tell us about recovery?
Read article Research perspective · 9 October 2026A demanding day can be exhausting without much movement. What does the research actually tell us about its energy cost?
Read article Research perspective · 7 October 2026What a study of older adults can tell us about life experience, ATP production and the limits of a metabolic explanation.
Read article Research perspective · 7 October 2026Why cellular energy belongs in the discussion of stress—and why blood-cell gene expression is not a diagnosis of brain energy deficiency.
Read article Research perspective · 7 October 2026Healthy underweight adults had higher-than-predicted resting expenditure—but also lower intake and activity. All three findings matter.
Read article Research perspective · 7 October 2026A mechanistic study shows why mitochondrial function involves cellular regulation as well as ATP production.
Read article Research perspective · 7 October 2026An eating plan should help the person live well. Understanding hunger and learned behaviour gives us better questions than whether someone obeyed the rules.
Read article Research perspective · 7 October 2026An extract from Consistent Eating, followed by a practical answer: build a pattern that nourishes you and can be repeated.
Read article Research perspective · 7 October 2026From the first edition’s activity table to today’s wearable estimates: how to use energy numbers without counting the same calories twice.
Read article Research perspective · 7 October 2026An original Consistent Eating figure explains why body mass gives useful context—and why kcal/kg is not a universal metabolic score.
Read article Research perspective · 5 October 2026What modern US dietary surveys and the famous US–Soviet calorie comparison can tell us about energy per kilogram—and what they cannot.
Read article Research perspective · 2 October 2026What a rare genetic disorder reveals about fat storage and mitochondrial function.
Read article Research perspective · 2 October 2026A mouse experiment comparing sucrose with starch raises a specific dietary-composition question.
Read article Research perspective · 2 October 2026A mechanistic mouse study connects lipid signalling with behaviour.
Read article Research perspective · 2 October 2026Controlled feeding evidence, metabolic adaptation and the limits of DCA claims.
Read article Research perspective · 2 October 2026The rationale and limits of an optional dietary-fat target.
Read article Research perspective · 2 October 2026A human crossover study separates dietary composition from weight change.
Read article Research perspective · 2 October 2026A tissue-specific response that deserves attention beyond the weighing scale.
Read article Research perspective · 2 October 2026Why a local hormone increase can accompany an improvement.
Read article Research perspective · 2 October 2026What a small combination-supplement trial can and cannot establish.
Read article Research perspective · 2 October 2026What human experiments reveal about restriction, stress and the biological effort of maintaining weight loss.
Read article Research perspective · 2 October 2026Why avoiding under-fuelling and supporting carbohydrate use are related but distinct questions for EPK.
Read article Research perspective · 2 October 2026What human studies reveal about liver fat, subcutaneous stores and changing fatty-acid composition during weight loss and ageing.
Read article Research perspective · 2 October 2026A controlled feeding study raises a question for EPK: can equal energy per kilogram produce different metabolic responses?
Read article Research perspective · 11 September 2026What Martin Picard’s research contributes to EPK: fuel supply, cellular utilisation and the energetic cost of stress.
Read article Research perspective · 11 September 2026Adherence, weight regain and the burden of restriction are different questions. The evidence supports asking all three.
Read article Research perspective · 11 September 2026Metabolism, hunger, behaviour and recovery in The Biology of Human Starvation — and what they mean for EPK.
Read article Research perspective · 11 September 2026Keys and colleagues documented the consequences of prolonged semi-starvation. Later reanalyses help frame questions about appetite and metabolic adaptation.
Read article Research perspective · 11 September 2026Stress biology helps explain why behaviour depends on physiological and social context. It does not reduce every stress response to insufficient calories.
Read article Research perspective · 11 September 2026Human evidence links some forms of energy restriction to disturbed sleep, but the response depends on the exposure and population.
Read article Research perspective · 11 September 2026Human studies connect under-fuelling with hormonal and functional changes, while showing why testosterone is not a calorie gauge.
Read article Research perspective · 11 September 2026A controlled human experiment connects sleep with body composition during dieting—and gives EPK a more specific recovery question.
Read article Research perspective · 11 September 2026Short walking studies connect activity patterns with glucose regulation, without equating acute glucose changes with long-term fat loss.
Read article Research perspective · 11 September 2026Controlled feeding studies help explain why fuel selection, food intake and body-fat change need separate measurements.
Read article Research perspective · 11 September 2026Exercise adaptation and lactate use show why energy throughput, useful work and cellular function must be distinguished.
Read article Research perspective · 11 September 2026Cognitive effort, food intake and energy expenditure are separate outcomes. Measuring each can make the brain-energy question more useful.
Read article Research perspective · 11 September 2026Body mass provides a useful scale, but age and tissue composition affect what an energy-per-kilogram value means.
Read article Research perspective · 11 September 2026Why total intake, exercise expenditure and fat-free mass must be measured separately.
Read article Research perspective · 11 September 2026A lifespan map that separates maternal needs, growth, resting metabolism and total daily requirements.
Read article Research perspective · 11 September 2026Cancer, older-age care and critical illness illustrate different uses of weight-based estimates.
Read article Research perspective · 11 September 2026Clinical intake guidance and measured resting metabolism offer distinct reference points for EPK.
Read article Research perspective · 11 September 2026Appetite feedback helps explain adherence problems without making diet failure inevitable.
Read article Research perspective · 11 September 2026Reduced exercise output does not automatically mean a lower resting metabolic rate.
Read article Research perspective · 11 September 2026Tracking lean mass alone can miss substantial losses of functional capacity.
Read article Research perspective · 11 September 2026Mobility and disease risk help test whether an energetic change is beneficial.
Read article Research perspective · 11 September 2026Exceptional longevity raises a useful question, but the available RMR evidence needs careful interpretation.
Read article Research perspective · 11 September 2026A testable question connecting energy intake, fuel switching and human function.
Read article Research perspective · 11 September 2026Six relevant PubMed papers, including findings that support, qualify and challenge the proposed mechanisms.
Read article Research perspective · 11 September 2026Why EPK research needs to distinguish fuel supply, oxidation and the ability to change fuels.
Read article Research perspective · 11 September 2026What cardiolipin and lipid–protein research can contribute to EPK.
Read article Research perspective · 11 September 2026Promising mitochondrial questions, with important gaps between experimental models and human outcomes.
Read article Research perspective · 11 September 2026A dendritic-cell study refines the proposed Proportional Danger Theory.
Read articleResearch principles
The archive is designed for clarity, permanence and constructive scrutiny—not for presenting an evolving hypothesis as settled fact.
Releases are dated and versioned. The original series and its revisions have version-specific DOIs; the new supplements also have permanent Zenodo DOIs. Original version 1.0 records remain available.
Clear summaries sit alongside definitions, methods, limitations and references.
Provisional propositions, limitations and research questions are stated so the framework can be examined empirically.
About
EPK Research is an independent project founded by Billy Craig to formalise, document and invite scrutiny of the Energy per Kilogram concept.
Paper 1 establishes the foundation for six connected working papers. Every original paper has a permanent DOI. Revised manuscripts have separate version labels and retain links to those original records.
Publication here does not imply peer review, clinical validation or scientific consensus. EPK thresholds remain provisional and the framework is presented as a testable hypothesis.
billy@enerjarden.com