Extended Fasting Calculator — Free Weight Loss Estimates
Extended fasting means going without food for longer than about 24 hours—and often several days. This free calculator estimates how much of your projected weight loss is burned fat versus temporary glycogen water, so a prolonged fast's headline number doesn't mislead you.
A 10-day duration is pre-selected to model a longer fast, but you can set any number of days. Enter your age, height, weight, and gender for a personalized fat-loss and water-weight breakdown.
Prolonged fasting is not a casual weight-loss shortcut. Multi-day water fasts carry real medical risks and often warrant clinical supervision—use these figures to set expectations, not as a target.
Multi-day modeling
Compounds daily fat loss at your TDEE across the full fast length.
Fat vs. water split
Separates lasting fat loss from the early glycogen water flush.
Ispunite podatke i kliknite Izračunaj gubitak težine za procijenjenu razradu.
What to know before you start
What counts as extended fasting?
Most clinicians describe fasts beyond 24 hours as extended or prolonged fasting, distinct from intermittent fasting windows like 16:8. As a fast lengthens, the body shifts from burning liver glycogen toward sustained fat oxidation and ketone production. That is why the first 72 hours show a large water drop on the scale while later days reflect steadier fat loss driven by your total daily energy expenditure.
This calculator uses the Mifflin-St Jeor BMR equation and a sedentary–lightly active TDEE multiplier to project fat loss for each day of the fast, while modeling early glycogen water separately. Because BMR falls with age and lower body mass, two people fasting the same number of days can see very different projected outcomes.
Safety during a prolonged fast
Extended water fasting can affect blood pressure, blood sugar, electrolytes, and heart rhythm. Pregnancy, breastfeeding, being underweight, eating disorders, type 1 diabetes, kidney disease, and many cardiovascular conditions are contraindications for unsupervised prolonged fasting, and several medications may need adjustment.
If you are considering a fast of several days, do it with medical guidance so a clinician can monitor vitals, electrolytes, and safe refeeding. Treat every estimate here as educational—not medical advice or a recommendation to fast longer.
Referentna Tablica Gubitka Težine Postom s Vodom
Primjer procjena za Muškarac od 35 godina, 175 cm, 80 kg. Vaši rezultati će se razlikovati—koristite kalkulator za personalizirane brojke.
| Trajanje posta | Vodena težina | Gubitak masti | Ukupna procjena | BMR / TDEE |
|---|---|---|---|---|
| 3 dana | 1.6 kg | 0.9 kg | 2.5 kg | 1,724 / 2,327 kcal |
| 4 dana | 1.7 kg | 1.2 kg | 3.0 kg | 1,724 / 2,327 kcal |
| 5 dana | 1.9 kg | 1.5 kg | 3.4 kg | 1,724 / 2,327 kcal |
| 7 dana | 2.2 kg | 2.1 kg | 4.3 kg | 1,724 / 2,327 kcal |
Što se događa dan po dan
Opći obrasci tijekom posta s vodom—korisno uz referentne razrade.
| Faza | Sati | Trend vode | Trend masti | Bilješke |
|---|---|---|---|---|
| Dan 1 | 0–24h | Nisko–umjereno | Minimalno | Glikogen počinje se iscrpljivati; blagi pad na vagi |
| Dan 2 | 24–48h | Umjereno–visoko | Nisko | Gubitak vode ubrzava kako glikogen pada |
| Dan 3 | 48–72h | Vrhunac | Umjereno | Većina glikogena nestala; najveći prozor vodene težine |
| Dani 4–5 | 72–120h | Smanjenje | Rastući udio | Oksidacija masti postaje veći dio ukupnog gubitka |
| Dani 6–7 | 120–168h | Nisko | Dominantno | Produženi post; često se savjetuje medicinski nadzor |
Procjene koriste BMR Mifflin-St Jeor, TDEE × 1,35, 3.500 cal/lb konverziju masti i model vodenog glikogena. Nije medicinski savjet.
Česta pitanja
Odgovori za ovu duljinu posta—pogledajte FAQ glavnog kalkulatora za cijeli FAQ.
Što je produženi post?
Koliko težine možete izgubiti tijekom sedmodnevnog vodnog posta?
Koliko težine gubite dnevno tijekom vodnog posta?
Je li ovaj kalkulator vodnog posta besplatan?
Više kalkulatora posta s vodom
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Vidi također: referentnu tablicu, provjerene resurse, FAQ
Medicinsko odricanje · Samo procjene—nije medicinski savjet.