Research

Hormonal

Dietary protein restriction, independent of energy intake, robustly increases circulating FGF21 levels in both rodents and humans, whereas energy restriction alone decreases or does not increase FGF21.

If you are consuming very low amounts of protein (e.g., <10% of calories), your body produces significantly more FGF21, a hormone that alters metabolism and growth. This response is driven by the lack of protein, not by how many calories you eat. Ensuring adequate protein intake prevents this specific hormonal stress response.

GoodSupportsHIGH confidence
These data demonstrate that protein restriction powerfully increases hepatic and circulating FGF21, whereas the opposite effect is observed when energy but not protein is restricted.
Thomas Laeger et al. · Journal of Clinical Investigation · 2014

Why this rating

Strong evidence across multiple models (rats, mice, humans) with consistent directional effects, though human data showed high variability.

Source

FGF21 is an endocrine signal of protein restriction

Thomas Laeger et al. · Journal of Clinical Investigation · 2014

DOI 10.1172/jci74915

mechanism_only · n=17Cited 590×
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DOI resolved against Crossref · corpus check 2026-06-10

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