Does high protein wreck your kidneys? Lore vs research
Published: 2026-06-18
Written by: Hirotsugu YoshimuraReviewed by: Tomonobu Someda
Gyms and the internet keep repeating that 'too much protein damages your kidneys.' How true is it for healthy people? We line up the claims against the research.
Let the data settle it.
Does high protein harm healthy kidneys?
What's said
一般的な通説・一部のフィットネス系YouTuber
Drinking lots of protein every day strains and damages your kidneys, so keep it moderate.
What research says
- In people with normal kidney function, there's no solid evidence that high protein (up to ~2.2 g/kg/day) causes kidney damage; meta-analyses of trials show no harmful effect on glomerular filtration rate.
For people with healthy kidneys the myth doesn't hold. Those with existing kidney disease are a different case and need medical guidance.
How much is actually enough?
What's said
ボディビル界の通説
The more protein the better — it just keeps building muscle.
What research says
- For hypertrophy, benefits largely plateau around 1.6 g/kg/day of total protein.
- More isn't harmful but adds little.
'More is better' is wrong. Aiming around 1.6 g/kg/day is the cost-effective target.
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Published: 2026-06-18
Written by
Hirotsugu YoshimuraFounder of BODYDATA / CEO of INVOLVE
I don't pick things because they "seem good." I check the data first, then test it with my own body.
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Reviewed by: Tomonobu Someda
Content reviewed from the perspective of coaching practice and supplement-industry experience