Research

Hormonal

Fasting-induced elevation of the myokine FGF21 is required for starvation-mediated muscle atrophy and weakness; its absence preserves muscle mass and force during caloric restriction.

If you are fasting or in a caloric deficit, your body actively uses the hormone FGF21 to break down muscle. This paper suggests that blocking this specific hormonal signal could theoretically preserve muscle mass even without food. While this is a mouse study, it highlights that muscle loss isn't just 'inevitable' during fasting but is driven by specific biological switches.

GoodSupportsHIGH confidence
FGF21 is required for fasting-induced muscle atrophy and weakness. ... FGF21-null muscles, however, were significantly protected from muscle loss and weakness during fasting.
Lynette J. Oost et al. · Journal of Cachexia Sarcopenia and Muscle · 2019

Why this rating

High-quality in vivo murine models with specific knockout and overexpression, though translational to humans is not explicitly tested.

Source

Fibroblast growth factor 21 controls mitophagy and muscle mass

Lynette J. Oost et al. · Journal of Cachexia Sarcopenia and Muscle · 2019

DOI 10.1002/jcsm.12409

mechanism_onlyCited 225×
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DOI resolved against Crossref · corpus check 2026-06-10

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