What does the evidence show about Extended fasting (24-72h+)'s effects?

Read Off Label rates the evidence for Extended fasting (24-72h+) as Moderate-Preclinical and the benefit magnitude as variable, producing an overall grade of C (4.6/10). Cheng/Longo work shows hematopoietic stem cell regeneration with 3-day fasts in mice (human data less mature).

What safety findings are reported for Extended fasting (24-72h+)?

Extended fasting (24-72h+) has a med risk profile in the database. Med (refeeding syndrome after longer fasts; electrolyte monitoring; muscle loss) Legal status: N/A.

What doses or routes are reported for Extended fasting (24-72h+)?

Reported protocols include periodic 24-72h fasts sometimes repeated quarterly to annually; electrolyte and refeeding considerations vary with duration and individual context This is context from studies, approved labeling, clinical practice, or documented use; it is not individualized guidance and does not establish safety.

Rankings / Metabolic Health

Extended fasting (24-72h+)

Metabolic Health · Fasting

Tier C

Reviewed by Read Off Label · Last reviewed Jun 8, 2026 · How we grade

autophagyfastinggh-axis

4.6 / 10

Tier C

Ev 4 Bn 5 Sf 5

Bottom line

Read Off Label grades Extended fasting (24-72h+) as C (4.6/10) based on moderate-preclinical evidence, variable benefit magnitude, and a med-risk safety profile.

Cheng/Longo work shows hematopoietic stem cell regeneration with 3-day fasts in mice (human data less mature).

Studied, labeled, or reported-use context: Reported protocols include periodic 24-72h fasts sometimes repeated quarterly to annually; electrolyte… — N/A; not individualized guidance.

Citation correction in progress

1 PubMed link was found to be unrelated to this entry and removed from public output. The remaining sources are shown below, but this row's claims and score still need a full source-by-source revalidation.

What the evidence says

Cheng/Longo work shows hematopoietic stem cell regeneration with 3-day fasts in mice (human data less mature). Risk rises rapidly past 72 hours without supervision. Water-only vs bone broth protocols differ.

Mechanism

Deep ketosis; extensive autophagy; stem cell mobilization (Longo); growth hormone elevation; complete insulin suppression; hematopoietic regeneration signals

Studied, labeled, or reported dose & route

Reported protocols include periodic 24-72h fasts sometimes repeated quarterly to annually; electrolyte and refeeding considerations vary with duration and individual context

This records doses and routes described in studies, approved labeling, clinical practice, or documented use. It is not individualized guidance and does not establish safety; context changes with indication, formulation, health history, monitoring, and other medicines.

Citations

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Common questions

What does the evidence show about Extended fasting (24-72h+)'s effects?: Read Off Label rates the evidence for Extended fasting (24-72h+) as Moderate-Preclinical and the benefit magnitude as variable, producing an overall grade of C (4.6/10). Cheng/Longo work shows hematopoietic stem cell regeneration with 3-day fasts in mice (human data less mature).
What safety findings are reported for Extended fasting (24-72h+)?: Extended fasting (24-72h+) has a med risk profile in the database. Med (refeeding syndrome after longer fasts; electrolyte monitoring; muscle loss) Legal status: N/A.
What doses or routes are reported for Extended fasting (24-72h+)?: Reported protocols include periodic 24-72h fasts sometimes repeated quarterly to annually; electrolyte and refeeding considerations vary with duration and individual context This is context from studies, approved labeling, clinical practice, or documented use; it is not individualized guidance and does not establish safety.
How does Extended fasting (24-72h+) work?: Deep ketosis; extensive autophagy; stem cell mobilization (Longo); growth hormone elevation; complete insulin suppression; hematopoietic regeneration signals

This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.