The Study
Higher circulating FGF21, lower protein intake, and lower muscle mass: Associations with a higher risk of mortality
This study looked at a bunch of people over many years and noticed that those with higher FGF21 levels tended to eat less protein and have less muscle, and also died more often. But it didn’t change anyone’s diet or give them medicine — it just watched what happened. So it can’t prove that FGF21 or low protein causes death — only that they often happen together.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
Your body releases a hormone called FGF21 when you don't eat enough protein. This hormone tells your body you're low on protein, and it's also linked to losing muscle and a higher chance of dying early.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 560 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes—eating enough protein helps keep your muscles strong and lowers your risk of dying early, even if you have other health problems.
- 2People with higher FGF21 had 48% higher odds of eating less than 0.8g protein per kg of body weight.
- 3Those who ate more protein had 33% lower risk of dying over 10 years.
- 4People with more muscle had 17% lower risk.
- 5FGF21 itself didn't cause death—low protein did.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Internal Medicine
Year
2025
Authors
A. Post, Wendy A Dam, D. Groothof, C. Franssen, S. J. Bakker, R. Dullaart
Related Content
Claims (6)
Without enough dietary protein, the body cannot build new muscle and will lose muscle mass over time.
Adults aged 28–75 who consume more dietary protein have a 33% lower risk of dying from any cause over 10 years, compared to those who consume less, even when accounting for differences in muscle mass, inflammation, and metabolic disease.
Adults aged 28–75 with higher muscle mass, measured by creatinine excretion relative to height, have a 17% lower risk of dying from any cause over 10 years, even when accounting for protein intake, inflammation, and metabolic disease.
In adults aged 28–75, higher levels of the protein FGF21 in the blood are linked to lower dietary protein intake, and a doubling of FGF21 concentration is associated with a 48% higher likelihood of consuming less than 0.8 grams of protein per kilogram of body weight per day. FGF21 levels are proposed as an indicator of long-term inadequate protein consumption.
Higher levels of the protein FGF21 are linked to a greater risk of death from any cause, but this link exists only because low protein intake causes both higher FGF21 levels and higher mortality risk; FGF21 itself does not cause death.
Higher levels of FGF21 in the blood are linked to lower muscle mass in adults, but this link exists only because people with higher FGF21 tend to consume less protein; when protein intake is accounted for, FGF21 shows no direct relationship with muscle mass.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.