Research
Hormonal
FGF21 is induced by fasting and acts as a glucagon-like hormone to promote ketogenesis, gluconeogenesis, and fatty acid oxidation during starvation.
FGF21 is a hormone that rises when you fast, helping your body burn fat and make ketones for energy. It is a natural part of the starvation response, ensuring you don't run out of glucose.
GoodSupportsHIGH confidence
FGF21 is strongly induced in the mouse liver by fasting >12 h... FGF21 induces hepatic expression of the transcriptional coactivator protein PGC-1a, which stimulates transcription of genes involved in each of these metabolic pathways [ketogenesis, gluconeogenesis, fatty acid oxidation].
Why this rating
Strong evidence from knockout mice and transgenic models showing metabolic shifts during fasting.
Source
Endocrine fibroblast growth factors 15/19 and 21: from feast to famine
Matthew J. Potthoff et al. · Genes & Development · 2012
DOI 10.1101/gad.184788.111
narrative_reviewCited 431×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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- FGF15/19 acts as an endocrine hormone to repress hepatic gluconeogenesis and stimulate glycogen synthesis, functioning as a post-prandial signal that complements insulin.Good
- Pharmacological administration of FGF21 improves insulin sensitivity, reduces hepatic triglycerides, and causes weight loss in obese rodents and primates.Good
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