{ "page": "https://jabbitapp.com/research/water-fasting-vs-ozempic-zepbound-muscle-loss-lean-mass-teardown.html", "checked": "2026-10-27 (America/New_York)", "notes": "Fasting studies are small, mostly uncontrolled, and use different body-composition methods (DXA, BIA, BIS, air displacement). The viral post's numbers are as reported by the post and were not verified. GLP-1 range from Jabbit's muscle-loss teardown (control arms of QUALITY, EMBRAZE, COURAGE, BELIEVE). No prices, doses, sellers or stacking.", "x_post": { "id": "2114816804166176827", "created_at": "2026-10-26T20:29:52.000Z", "read_at_et": "2026-10-27 ~6:03 PM ET", "public_metrics": { "bookmark_count": 813, "impression_count": 988584, "like_count": 1500, "quote_count": 17, "reply_count": 208, "retweet_count": 86 }, "text_excerpt_quoted": [ "did a 14-day water-only fast and got a DEXA scan before and after.", "about 13 lbs of fat lost, and about 7 lbs of lean mass lost.", "That means roughly 1 in every 3 pounds he lost wasn’t fat.", "The internet keeps saying extended fasting “spares muscle,”" ], "note": "Poster (a private individual) and the person described are not named on the page." }, "x_counts": { "query": "(\"water fast\" OR \"water fasting\") lang:en -is:retweet", "read_at_et": "2026-10-27 ~6:03 PM ET", "granularity": "day (UTC)", "days": { "2026-10-21": 69, "2026-10-22": 86, "2026-10-23": 90, "2026-10-24": 56, "2026-10-25": 41, "2026-10-26": 70, "2026-10-27_partial_to_22:03Z": 78 }, "total_7d": 496 }, "pubmed_search_fasting_glp1": { "term": "(\"prolonged fasting\"[Title/Abstract] OR \"water-only fasting\"[Title/Abstract] OR \"water fasting\"[Title/Abstract]) AND (\"semaglutide\"[Title/Abstract] OR \"tirzepatide\"[Title/Abstract] OR \"liraglutide\"[Title/Abstract] OR \"GLP-1\"[Title/Abstract])", "run": "2026-10-27 ~6:30 PM ET", "count": 21, "idlist": [ "42783483", "42553740", "42538551", "42502140", "42069389", "41998348", "41922235", "41266825", "41036293", "41007653", "40807216", "40142805", "25905318", "39418085", "39187641", "35730880", "30714432", "29105987", "23997935", "19094067", "10490778" ], "note": "Jabbit screened titles: one case report (41998348) combined prolonged water fasting with a GLP-1 drug; the rest are about perioperative fasting, endoscopy, Ramadan or lab studies." }, "pubmed": { "37377031": { "title": "Efficacy and safety of prolonged water fasting: a narrative review of human trials", "quotes": [ "prolonged fasting for 5-20 days produces potent increases in circulating ketones, and mild to moderate weight loss of 2-10%", "Approximately two-thirds of the weight lost is lean mass, and one-third is fat mass.", "The excessive lean mass loss suggests that prolonged fasting may increase the breakdown of muscle proteins, which is a concern.", "3-4 months after the fast was completed, all metabolic benefits were no longer observed, even when weight loss was maintained", "metabolic acidosis, headaches, insomnia, and hunger were observed in some studies" ] }, "42440276": { "title": "Duration-Dependent Changes in Body Composition During Prolonged Fasting: A Systematic Review and Meta-Analysis", "quotes": [ "A total of 49 studies met the inclusion criteria", "fat mass (g = -0.25), fat-free mass (g = -0.51), total body water (g = -0.68)", "is also associated with substantial losses in fat-free mass and total body water, indicating that fasting-induced weight loss reflects complex changes in body composition rather than isolated fat loss", "No clear duration-dependent effects were observed for most outcomes." ] }, "34668663": { "title": "Is muscle and protein loss relevant in long-term fasting in healthy men? A prospective trial on physiological adaptations", "quotes": [ "Sixteen men (44 ± 14 years; 26.2 ± 0.9 kg/m2 ) fasted with a supplement of 200-250 kcal/day", "The 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", "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%).", "Strength was maintained in non-weight-bearing muscles and increased in weight-bearing muscles (+33%, P < 0.001).", "Protein loss occurs in early fast but decreases as ketogenesis increases." ] }, "38429390": { "title": "Systemic proteome adaptions to 7-day complete caloric restriction in humans", "quotes": [ "a 7-day water-only fast leads to an average weight loss of 5.7 kg (±0.8 kg) among 12 volunteers (5 women, 7 men)", "systemic changes evident only after 3 days of complete calorie restriction" ] }, "40268190": { "title": "Prolonged fasting promotes systemic inflammation and platelet activation in humans: A medically supervised, water-only fasting and refeeding study", "quotes": [ "a medically supervised water-only fast (mean duration: 9.8 ± 3.1 days)", "Fasting resulted in a 7.7% mean weight loss", "PF induced an acute inflammatory response, characterized by elevated plasma C-reactive protein (CRP)", "it raises concerns regarding potential cardiometabolic effects that could persist after refeeding" ] }, "42754908": { "title": "Machine learning identifies microbiome and clinical predictors of sustained weight loss following prolonged fasting", "quotes": [ "38 healthy adults completed a 5-day fasting intervention with 12-week follow-up (LEANER study)", "Fasting reduced body mass index acutely, predominantly driven by loss of fat mass, and these improvements partially persisted at 12 weeks." ] }, "29458369": { "title": "Is fasting safe? A chart review of adverse events during medically supervised, water-only fasting", "quotes": [ "Out of 2539 charts, 768 visits met our inclusion and exclusion criteria.", "in 212 visits it was a grade 3 event, in 1 visit it was a grade 4 event, and there were no grade 5 events", "There were 2 (0.002%) visits with a serious adverse event (SAE)." ] }, "30601864": { "title": "Safety, health improvement and well-being during a 4 to 21-day fasting period in an observational study including 1422 subjects", "quotes": [ "1422 subjects participated in a fasting program consisting of fasting periods of between 4 and 21 days", "with a daily caloric intake of 200-250 kcal", "Adverse effects were reported in less than 1% of the participants.", "Buchinger periodic fasting within a specialised clinic" ] }, "24447775": { "title": "Weight loss composition is one-fourth fat-free mass: a critical review and critique of this widely cited rule", "quotes": [ "approximately one-fourth of weight loss will be FFM (i.e. ΔFFM/ΔWeight = ∼0.25)" ] }, "5454322": { "title": "Prolonged starvation--a dangerous procedure?", "quotes": [ "Experience with 18 obese patients who have undergone prolonged (60 days) therapeutic starvation shows that in general this is a safe procedure, but there are significant associated hazards, particularly a breakdown in electrolyte homoeostasis." ] }, "6061736": { "title": "Brain metabolism during fasting", "quotes": [ "beta-hydroxybutyrate and acetoacetate replaced glucose as the predominant fuel for brain metabolism" ] }, "5773094": { "title": "Amino acid metabolism during prolonged starvation", "quotes": [ "protein catabolism is minimized in prolonged fasting" ] }, "1615908": { "title": "Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition", "quotes": [ "Glycogen is stored in the liver, muscles, and fat cells in hydrated form (three to four parts water)", "Potassium released from glycogen can distort estimates of body composition during dieting." ] }, "4803438": { "title": "Features of a successful therapeutic fast of 382 days' duration", "quotes": [ "A 27-year-old male patient fasted under supervision for 382 days", "Decreased plasma magnesium concentrations were a consistent feature from the first month onwards." ] }, "41998348": { "title": "Combination of prolonged water fasting and GLP-1 for refractory morbid obesity: Case report", "quotes": [ "none focused on patients with severe obesity (body mass index ≥ 40) or utilized treatment with glucagon-like peptide-1 receptor agonists (GLP-1)", "He underwent a 27 day inpatient fast with weekly tirzepatide, including 21 day water fast with structured refeeding.", "The patient lost 125 pounds during the fast.", "the only complication was mild transaminitis" ] }, "38937282": { "title": "Changes in lean body mass with glucagon-like peptide-1-based therapies and mitigation strategies", "quotes": [ "in some studies, reductions in lean mass range between 40% and 60% as a proportion of total weight lost, while other studies show lean mass reductions of approximately 15% or less of total weight lost", "includes not only muscle but also organs, bone, fluids, and water in fat tissue" ] } }, "full_text_quotes": { "PMC11494232.txt": [ "Only 2 studies 17 , 21 measured changes in fat mass and lean mass during prolonged fasting", "After 8 days of water-only fasting, body weight decreased by 6 kg, fat mass by 2 kg, and lean mass by 4 kg.", "In the study by Dai et al 17 changes in body composition were quantified by dual-energy X-ray absorptiometry (DXA).", "Following a 10-day water fast, body weight decreased by 7 kg, fat mass by 3 kg, and lean mass by 4 kg.", "In the study by Ogłodek et al 21 changes in body composition were measured by bioelectrical impedance analysis (BIA).", "Reductions in lean mass can translate into lower resting metabolic rate after fasting, which can put individuals at risk for future weight regain.", "the effects of refeeding on these body composition parameters remain unknown", "No serious adverse events or deaths were reported in any of the studies reviewed here." ], "PMC8718030.txt": [ "for 42% by metabolic active (liver, kidneys, heart, intestine, muscles, etc.) tissues (1.5 ± 0.1 kg representing 25% of weight loss)", "explained for 44% (−1.6 ± 0.1 kg) by extracellular water loss (which includes loss of faeces by enemas), for 14% (0.50 ± 0.01 kg) by early glycogen loss and its associated water", "Weight loss during fasting was explained by changes in both FM and LST (−2.34 ± 0.18 kg and −3.53 ± 0.13 kg, respectively, after 10 days of fasting", "we observed that body mass and LST, but not FM, remained lower at Fup", "We cannot specifically ascertain how much muscle mass breakdown explained the LST decrease.", "This study was funded by the CNRS and Amplius GmbH, Überlingen, Germany.", "is managing director of Amplius GmbH, a company that coordinates the scientific documentation for the Buchinger Wilhelmi Clinics and is co‐worker of the Buchinger Wilhelmi Clinic", "Franziska Grundler is co‐worker at the Buchinger Wilhelmi Clinic.", "in 16 healthy men", "This longitudinal non‐controlled intervention was conducted between November and December 2016 at the Buchinger Wilhelmi Clinic" ], "PMC5819235.txt": [ "The median fasting length was 7 (IQR 6) days; the shortest fast was 2 days and longest fast was 41 days.", "fatigue ( n = 370, 48.2%), nausea ( n = 247, 32.2%), insomnia ( n = 257, 33.5%), headache ( n = 231, 30.1%), hypertension ( n = 224, 29.2%), presyncope ( n = 217, 28.3%)", "Of the 77 visits with a grade 3 hypertension AE, 75 had hypertension as a chief complaint upon arrival.", "One was a grade 3 dehydration event that occurred on fasting day 3 in a 73-year-old, male patient.", "The other was a grade 4 hyponatremia event that occurred on fasting day 9 in a 70-year-old, male patient.", "Additional support was provided by the TrueNorth Health Foundation." ], "PMC12088818.txt": [ "women losing 6.3 ± 1.7 kg and men losing 6.9 ± 2.2 kg", "is the founder of TrueNorth Health Center, a private facility that offers medically supervised fasting interventions" ], "PMC13587497.txt": [ "The fasting intervention consisted of a 5-day period with 250 kcal/day", "determined body composition (lean and fat mass) by air displacement plethysmography", "the absolute and relative reduction of body fat was accompanied by a reduction in lean mass during fasting that completely reverted at follow-up", "the absence of an active dietary comparator in LEANER", "Exclusion criteria were heart, lung, liver, and kidney diseases requiring medical intervention, prescribed medication (except oral contraceptives)" ], "PMC2440847.txt": [ "The hallmark biochemical feature of refeeding syndrome is hypophosphataemia.", "Little or no nutritional intake for >5 days", "The NICE guidelines recommend that refeeding is started at no more than 50% of energy requirements in “patients who have eaten little or nothing for more than 5 days." ] }, "charts": { "lean_share_pct_of_weight_lost": { "water_fast_8d_BIA_Oglodek_via_Ezpeleta": 67, "water_fast_10d_DXA_Dai_via_Ezpeleta": 57, "buchinger_10d_Laurens_lean_soft_tissue": 60.7, "buchinger_10d_Laurens_metabolically_active_only": 25, "viral_post_14d_reported": 35, "glp1_trial_control_arms_DXA_range": [ 28.9, 34 ], "quarter_rule_Heymsfield": 25 }, "laurens_breakdown_kg": { "fat": 2.34, "extracellular_water": 1.6, "glycogen_and_water": 0.5, "metabolically_active_tissue": 1.5 } } }