The Study
Comparative effects of low-carbohydrate high-protein versus low-fat diets on the kidney.
This study compared two diets in people who are overweight but otherwise healthy, and found that one diet made some kidney markers change a little — like how much urine they made or how much calcium was in it. But it didn’t prove that one diet causes kidney damage or keeps it safe — it just showed what happened over two years in this group.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
This study looked at whether eating a lot of protein while cutting carbs harms the kidneys in obese people trying to lose weight.
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 574 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1These changes are normal kidney responses to high protein — like a car engine revving higher, not breaking down.
- 2Protein diet raised urine calcium by 36% and blood urea by 14% at 3 months, and made kidneys filter more blood (by 21 mL/min) at 12 months — but didn't cause protein in urine, bone loss, or kidney stones.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Clinical journal of the American Society of Nephrology : CJASN
Year
2012
Authors
A. Friedman, Lorraine G. Ogden, G. Foster, S. Klein, R. Stein, Bernard V. Miller, James O Hill, Carrie Brill, B. Bailer, Diane R Rosenbaum, H. Wyatt
Related Content
Claims (6)
Eating a high-protein diet does not damage the kidneys in people with healthy kidney function, even though it raises levels of creatinine and urea in the blood.
In healthy obese adults, switching to a low-carbohydrate, high-protein diet for up to 24 months increases calcium loss in urine by about 36% at 3 and 12 months compared to a low-fat diet, but does not change bone density or cause kidney stones.
Over 24 months, a low-carbohydrate high-protein diet does not change the amount of albumin in the urine of healthy obese adults compared to a low-fat diet.
In healthy obese adults, switching from a low-fat diet to a low-carbohydrate high-protein diet for 24 months results in a 14.4% increase in serum urea levels at 3 months and an 8.2% increase at 24 months, indicating higher protein breakdown without signs of kidney dysfunction.
In healthy obese adults, following a low-carbohydrate high-protein diet for two years does not change blood levels of sodium, potassium, chloride, or bicarbonate compared to a low-fat diet.
In healthy obese adults, a low-carbohydrate, high-protein diet for 24 months causes a temporary rise in creatinine clearance and a lasting increase in serum urea, with no change in albuminuria or electrolyte levels, indicating increased kidney filtration without signs of kidney damage.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.