Comparative effects of low-carbohydrate high-protein versus low-fat diets on the kidney

Allon N. Friedman, Lorraine G. Ogden, Gary D. Foster, Samuel Klein, Richard Stein, Bernard Miller, James O. Hill, Carrie Brill, Brooke Bailer, Diane R. Rosenbaum, Holly R. Wyatt

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76 Scopus citations


Background and objectives Concerns exist about deleterious renal effects of low-carbohydrate high-protein weight loss diets. This issue was addressed in a secondary analysis of a parallel randomized, controlled long-term trial. Design, setting, participants, and measurements Between 2003 and 2007, 307 obese adults without serious medical illnesses at three United States academic centers were randomly assigned to a low-carbohydrate highprotein or a low-fatweight-loss diet for 24months. Main outcomes included renal filtration (GFR) indices (serum creatinine, cystatin C, creatinine clearance); 24-hour urinary volume; albumin; calcium excretion; and serum solutes at 3, 12, and 24 months. Results Comparedwith the low-fat diet, low-carbohydrate high-protein consumptionwas associatedwithminor reductions in serum creatinine (relative difference, 24.2%) and cystatin C (28.4%) at 3 months and relative increases in creatinine clearance at 3 (15.8 ml/min) and 12 (20.8 ml/min) months; serum urea at 3 (14.4%), 12 (9.0%), and 24 (8.2%) months; and 24-hour urinary volume at 12 (438 ml) and 24 (268 ml)months.Urinary calcium excretion increased at 3 (36.1%) and 12 (35.7%)months without changes in bone density or clinical presentations of new kidney stones. Conclusions In healthy obese individuals, a low-carbohydrate high-protein weight-loss diet over 2 yearswas not associatedwith noticeably harmful effects on GFR, albuminuria, or fluid and electrolyte balance comparedwith a low-fat diet. Further follow-up is needed to determine even longer-term effects on kidney function.

Original languageEnglish
Pages (from-to)1103-1111
Number of pages9
JournalClinical Journal of the American Society of Nephrology
Issue number7
StatePublished - Jul 1 2012


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