Trial reportJournal of cachexia, sarcopenia and muscle2021
Is muscle and protein loss relevant in long-term fasting in healthy men? A prospective trial on physiological adaptations.
Trial report in Journal of cachexia, sarcopenia and muscle, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT07155993 (FastForward), which is not on this map. Cited by 31 papers, 2 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
FastForward: A Prospective Analysis of Long-term Fasting and Subsequent Food Reintroduction in Humans
Who cites it
31 citing papers in PubMed, 2 syntheses or guidelines pooled it, 49 citations in OpenAlex.
- Pooled it
- Comparing caloric restriction regimens for effective weight management in adults: a systematic review and network meta-analysis.The international journal of behavioral nutrition and physical activity · 2024Pooled it
- Study protocol for FAXAge: a randomized, controlled clinical trial of fasting and exercise to slow aging in humans.GeroScience · 2026Trial
- Machine learning identifies microbiome and clinical predictors of sustained weight loss following prolonged fasting.Genome medicine · 2026Trial
- The effect of 6-day fasting on physical performance and neuromuscular control in healthy men.Scientific reports · 2026Trial
- Sex-related differences in fine motor skills and muscle strength control during short-term fasting.Scientific reports · 2026Trial
- Protein oxidation in non-exercising healthy adults under varying dietary conditions: Physiological determinants, effects on fuel partitioning, and implications for body weight regulation.Metabolism: clinical and experimental · 2025Trial
- Prolonged Water-Only Fasting Followed by a Whole-Plant-Food Diet Is a Potential Long-Term Management Strategy for Hypertension and Obesity.Nutrients · 2024Trial
- Trial
- Intermittent fasting two days versus one day per week, matched for total energy intake and expenditure, increases weight loss in overweight/obese men and women.Nutrition journal · 2022Trial
- Is muscle and protein loss relevant in long-term fasting in healthy men? A prospective trial on physiological adaptations.Journal of cachexia, sarcopenia and muscle · 2021Trial
- Skeletal muscle mass is not compositionally uniform: the role of fluid compartments in health and performance monitoring.European journal of clinical nutrition · 2026Review
- Endocrine Adaptations to Prolonged Fasting: From Physiology, Clinical Uncertainties, Translational Challenges to Healthspan Implications.Nutrients · 2025Review
- Prolonged Water-Only Fasting Followed by a Whole-Plant-Food Diet Promotes Fat-Free Mass Recovery and Continued Fat Mass Loss in Adults With Overweight or Obesity.Obesity science & practice · 2025Article
- The flux of energy in critical illness and the obesity paradox.Physiological reviews · 2025Review
- Sex-specific Mendelian randomization phenome-wide association study of basal metabolic rate.Scientific reports · 2025Article
- Impact of Long-Term Fasting on Skeletal Muscle: Structure, Energy Metabolism and Function UsingJournal of cachexia, sarcopenia and muscle · 2025Article
- The role of β-hydroxybutyrate testing in ketogenic metabolic therapies.Frontiers in nutrition · 2025Review
- Effects of Long-Term Fasting on Gut Microbiota, Serum Metabolome, and Their Association in Male Adults.Nutrients · 2024Article
- Dietary recommendations of the Moroccan Society of Rheumatology (SMR) for patients with ostéosarcopenia.Archives of osteoporosis · 2024Review
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
12 authors at 8 institutions in 4 countries.
Funding
Abstract
backgroundFasting is attracting an increasing interest as a potential strategy for managing diseases, including metabolic disorders and complementary cancer therapy. Despite concerns of clinicians regarding protein catabolism and muscle loss, evidence-based clinical data in response to long-term fasting in healthy humans are scarce. The objective of this study was to measure clinical constants, metabolic, and muscular response in healthy men during and after a 10 day fast combined with a physical activity programme.
methodsSixteen men (44 ± 14 years; 26.2 ± 0.9 kg/m
resultsThe 10 day fast decreased BW by 7% (-5.9 ± 0.2 kg, P < 0.001) and BMR by 12% (P < 0.01). Fat mass and lean soft tissues (LST) accounted for about 40% and 60% of weight loss, respectively, -2.3 ± 0.18 kg and -3.53 ± 0.13 kg, P < 0.001. LST loss was explained by the reduction in extracellular water (44%), muscle and liver glycogen and associated water (14%), and metabolic active lean tissue (42%). Plasma 3-methyl-histidine increased until Day 5 of fasting and then decreased, suggesting that protein sparing might follow early proteolysis. Daily steps count increased by 60% (P < 0.001) during the fasting period. Strength was maintained in non-weight-bearing muscles and increased in weight-bearing muscles (+33%, P < 0.001). Glycaemia, insulinemia, blood lipids, and blood pressure dropped during the fast (P < 0.05 for all), while non-esterified fatty acids and urinary beta-hydroxybutyrate increased (P < 0.01 for both). After a transient reduction, inflammatory cytokines returned to baseline at Day 10 of fasting, and LST were still lower than baseline values (-2.3% and -3.2%, respectively; P < 0.05 for both).
conclusionsA 10 day fast appears safe in healthy humans. Protein loss occurs in early fast but decreases as ketogenesis increases. Fasting combined with physical activity does not negatively impact muscle function. Future studies will need to confirm these first findings.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.